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Páez DJ, Kurath G, Powers RL, Naish KA, Purcell MK. Local and systemic replicative fitness for viruses in specialist, generalist, and non-specialist interactions with salmonid hosts. J Gen Virol 2024; 105. [PMID: 38180085 DOI: 10.1099/jgv.0.001937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024] Open
Abstract
Host tissues represent diverse resources or barriers for pathogen replicative fitness. We tested whether viruses in specialist, generalist, and non-specialist interactions replicate differently in local entry tissue (fin), and systemic target tissue (kidney) using infectious hematopoietic necrosis virus (IHNV) and three salmonid fish hosts. Virus tissue replication was host specific, but one feature was shared by specialists and the generalist which was uncommon in the non-specialist interactions: high host entry and replication capacity in the local tissue after contact. Moreover, specialists showed increased replication in systemic target tissues early after host contact. By comparing ancestral and derived IHNV viruses, we also characterized replication tradeoffs associated with specialist and generalist evolution. Compared with the ancestral virus, a derived specialist gained early local replicative fitness in the new host but lost replicative fitness in the ancestral host. By contrast, a derived generalist showed small replication losses relative to the ancestral virus in the ancestral host but increased early replication in the local tissue of novel hosts. This study shows that the mechanisms of specialism and generalism are host specific and that local and systemic replication can contribute differently to overall within host replicative fitness for specialist and generalist viruses.
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Affiliation(s)
- David J Páez
- U.S. Geological Survey, Western Fisheries Research Center, Marrowstone Marine Field Station, 616 Marrowstone Point Road, Nordland, WA 98358, USA
| | - Gael Kurath
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA
| | - Rachel L Powers
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA
| | - Kerry A Naish
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA
| | - Maureen K Purcell
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA
- U.S. Geological Survey, Forest Rangeland Ecosystem Science Center, Corvallis, OR 97330, USA
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Mattheiss JP, Breyta R, Kurath G, LaDeau SL, Páez DJ, Ferguson PFB. Coproduction and modeling spatial contact networks prevent bias about infectious hematopoietic necrosis virus transmission for Snake River Basin salmonids. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 334:117415. [PMID: 36780814 DOI: 10.1016/j.jenvman.2023.117415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 01/23/2023] [Accepted: 01/28/2023] [Indexed: 06/18/2023]
Abstract
Much remains unknown about variation in pathogen transmission across the geographic range of a free-ranging fish or animal species and about the influence of movement (associated with husbandry practices or animal behavior) on pathogen transmission. Salmonid hatcheries are an ideal system in which to study these processes. Salmonid hatcheries are managed for endangered species recovery, supplementation of threatened or at-risk fish stocks, support of fisheries, and ecosystem stability. Infectious hematopoietic necrosis virus (IHNV) is a rhabdovirus of significant concern to salmon aquaculture. Landscape IHNV transmission dynamics previously had been estimated only for salmonid hatcheries in the Lower Columbia River Basin (LCRB). The objectives of this study were to estimate IHNV transmission dynamics in a unique geographic region, the Snake River Basin (SRB), and to quantitatively estimate the effect of model coproduction on inference because previous assessments of coproduction have been qualitative. In contrast to the LCRB, the SRB has hatchery complexes consisting of a main hatchery and ≥1 satellite facility. Knowledge about hatchery complexes was held by a subset of project researchers but would not have been available to project modelers without coproduction. Project modelers generated and tested multiple versions of Bayesian susceptible-exposedinfected models to realistically represent the SRB and estimate the effect of coproduction. Models estimated the frequency of transmission routes, route-specific infection probabilities, and infection probabilities for combinations of salmonid hosts and IHNV lineages. Model results indicated that in the SRB, avoiding exposure to IHNV-positive adult salmonids is the most important action to prevent juvenile infections. Migrating adult salmonids exposed juvenile cohort-sites most frequently, and the infection probability was greatest following exposure to migrating adults. Without coproduction, the frequency of exposure by migrating adults would have been overestimated by 70 cohort-sites, and the infection probability following exposure to migrating adults would have been underestimated by∼0.09. The coproduced model had less uncertainty in the infection probability if no transmission route could be identified (Bayesian credible interval (BCI) width = 0.12) compared to the model without coproduction (BCI width = 0.34). Evidence for virus lineage MD specialization on steelhead and rainbow trout (both Oncorhynchus mykiss) was apparent without model coproduction. In the SRB, we found a greater probability of virus lineage UC infection in Chinook salmon (Oncorhynchus tshawytscha) compared to in O. mykiss, whereas in the LCRB, UC more clearly exhibited a generalist approach. Coproduction influenced estimates that depended on transmission routes, which operated differently at main hatcheries and satellite sites within hatchery complexes. Hatchery complexes are found outside of the SRB and are not specific to salmonid hatcheries alone. There is great potential for coproduction and modeling spatial contact networks to advance understanding about infectious disease transmission in complex production systems and surrounding free-ranging animal populations.
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Affiliation(s)
- Jeffrey P Mattheiss
- 1325 Science and Engineering Complex, 300 Hackberry Lane, Tuscaloosa, AL 35487 University of Alabama, Tuscaloosa, AL, 35487, USA.
| | - Rachel Breyta
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, 98115, USA.
| | - Gael Kurath
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, 98115, USA.
| | - Shannon L LaDeau
- Cary Institute of Ecosystem Studies, 2801 Sharon Turnpike, Millbrook, NY, 12545, USA.
| | - David J Páez
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, 98115, USA.
| | - Paige F B Ferguson
- 1325 Science and Engineering Complex, 300 Hackberry Lane, Tuscaloosa, AL 35487 University of Alabama, Tuscaloosa, AL, 35487, USA.
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Yang Y, Ren Y, Zhang Y, Wang G, He Z, Liu Y, Cao W, Wang Y, Chen S, Fu Y, Hou J. A New Cell Line Derived from the Spleen of the Japanese Flounder ( Paralichthys olivaceus) and Its Application in Viral Study. BIOLOGY 2022; 11:biology11121697. [PMID: 36552207 PMCID: PMC9774307 DOI: 10.3390/biology11121697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/21/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022]
Abstract
A new cell line Japanese flounder spleen (JFSP) derived from the spleen of Japanese flounder (Paralichthys olivaceus) was established and characterized in this study. The JFSP cells grew rapidly at 29 °C, and the optimum fetal bovine serum concentration in the L-15 medium was 15%. Cells were subcultured for more than 80 passages. The JFSP cells have a diploid chromosome number of 2n = 68, which differs from the chromosome number of normal diploid Japanese flounder. The established cells were susceptible to Bohle virus (BIV), Viral hemorrhagic septicemia virus (VHSV), Hirame rhabdovirus (HIRRV), Infectious hematopoietic necrosis virus (IHNV), and Lymphocystis disease virus (LCDV), as evidenced by varying degrees of cytopathic effects (CPE). Replication of the virus in JFSP cells was confirmed by qRT-PCR and transmission electron microscopy. In addition, the expression of four immune-related genes, TRAF3, IL-1β, TNF-α, and TLR2, was differentially altered following viral infection. The results indicated that the cells underwent an antiviral immune response. JFSP cell line is an ideal tool in vitro for virology. The use of fish cell lines to study the immune genes and immune mechanism of fish and to clarify the immune mechanism of fish has important theoretical significance and practical application value for the fundamental prevention and treatment of fish diseases.
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Affiliation(s)
- Yucong Yang
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai 201306, China
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding Genetics, Shanghai Ocean University, Shanghai 201306, China
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Yuqin Ren
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Yitong Zhang
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Guixing Wang
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Zhongwei He
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Yufeng Liu
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Wei Cao
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Yufen Wang
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
| | - Songlin Chen
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China
| | - Yuanshuai Fu
- Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai 201306, China
- Shanghai Collaborative Innovation for Aquatic Animal Genetics and Breeding Genetics, Shanghai Ocean University, Shanghai 201306, China
- Correspondence: (Y.F.); (J.H.)
| | - Jilun Hou
- Hebei Key Laboratory of the Bohai Sea Fish Germplasm Resources Conservation and Utilization, Beidaihe Central Experiment Station, Chinese Academy of Fishery Sciences, Qinhuangdao 066100, China
- Correspondence: (Y.F.); (J.H.)
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Li J, Xia D, Zhang M, Zhang Y, Liu X, Sun J, Xu B, Yang J, Wang N, Shi W, Guan X, Liu M. Infectious hematopoietic necrosis virus (IHNV) nucleoprotein amino acid residues affect viral virulence and immunogenicity in rainbow trout (Oncorhynchus mykiss). FISH & SHELLFISH IMMUNOLOGY 2022; 130:572-581. [PMID: 35988711 DOI: 10.1016/j.fsi.2022.08.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/10/2022] [Accepted: 08/13/2022] [Indexed: 06/15/2023]
Abstract
This study compared the N protein sequences of genotype J with other genotypes of IHNV to select amino acid residues that may be related to the change in viral virulence. The recombinant viruses containing different mutation sites were rescued by alanine scanning mutagenesis and the reverse genetic system. The nine recombinant virus strains obtained in this work were named rIHNV-N85, rIHNV-N102, rIHNV-N146, rIHNV-N380, rIHNV-N85-102-146, rIHNV-N85-102-380, rIHNV-N85-146-380, rIHNV-N102-146-380, and rIHNV-N85-102-146-380. Pathogenicity and immunity assays were performed to determine the role of virulence sites. The result of the pathogenicity test showed that the survival rates of rIHNV-N85, rIHNV-N102, rIHNV-N85-102-146, and rIHNV-N85-102-380 groups were 52.5%, 55%, 67.5%, and 57.5%, while the survival rate of wild-type (wt) IHNV HLJ-09 group was only 10%. The replication ability of recombinant viruses with substitutions at positions 85 and 102 was significantly inhibited in vivo and in vitro. The qRT-PCR result indicated that the cytokines of IFN1, IL-8, and IL-1β expression levels were increased in rIHNV-N85, rIHNV-N102, rIHNV-N85-102-146, and rIHNV-N85-102-380 groups. In addition, these four recombinant viruses could cause the rainbow trout to produce anti-IHNV-specific antibodies immunoglobulin M (IgM) earlier, confirming that 85 and 102 amino acid residues of N protein affected the virulence and immunogenicity of IHNV. All these results suggest that mutations of the N protein virulence sites reduce virulence while retaining immunogenicity. This also provides a new idea for studying the virulence mechanism of rhabdoviruses and preparing attenuated vaccines.
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Affiliation(s)
- Jiahui Li
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Dong Xia
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Mengmeng Zhang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Yanru Zhang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Xuefei Liu
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Jinhui Sun
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Baoxing Xu
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Jiawei Yang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Na Wang
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Wen Shi
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China
| | - Xueting Guan
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China; Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Guangdong Ocean University, Zhanjiang, 524025, People's Republic of China.
| | - Min Liu
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, People's Republic of China.
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Páez DJ, McKenney D, Purcell MK, Naish KA, Kurath G. Variation in within-host replication kinetics among virus genotypes provides evidence of specialist and generalist infection strategies across three salmonid host species. Virus Evol 2022; 8:veac079. [PMID: 36101884 PMCID: PMC9463992 DOI: 10.1093/ve/veac079] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/23/2022] [Indexed: 02/12/2024] Open
Abstract
Theory of the evolution of pathogen specialization suggests that a specialist pathogen gains high fitness in one host, but this comes with fitness loss in other hosts. By contrast, a generalist pathogen does not achieve high fitness in any host, but gains ecological fitness by exploiting different hosts, and has higher fitness than specialists in nonspecialized hosts. As a result, specialist pathogens are predicted to have greater variation in fitness across hosts, and generalists would have lower fitness variation across hosts. We test these hypotheses by measuring pathogen replicative fitness as within-host viral loads from the onset of infection to the beginning of virus clearance, using the rhabdovirus infectious hematopoietic necrosis virus (IHNV) in salmonid fish. Based on field prevalence and virulence studies, the IHNV subgroups UP, MD, and L are specialists, causing infection and mortality in sockeye salmon, steelhead, and Chinook salmon juveniles, respectively. The UC subgroup evolved naturally from a UP ancestor and is a generalist infecting all three host species but without causing severe disease. We show that the specialist subgroups had the highest peak and mean viral loads in the hosts in which they are specialized, and they had low viral loads in nonspecialized hosts, resulting in large variation in viral load across hosts. Viral kinetics show that the mechanisms of specialization involve the ability to both maximize early virus replication and avoid clearance at later times, with different mechanisms of specialization evident in different host-virus combinations. Additional nuances in the data included different fitness levels for nonspecialist interactions, reflecting different trade-offs for specialist viruses in other hosts. The generalist UC subgroup reached intermediate viral loads in all hosts and showed the smallest variation in fitness across hosts. The evolution of the UC generalist from an ancestral UP sockeye specialist was associated with fitness increases in steelhead and Chinook salmon, but only slight decreases in fitness in sockeye salmon, consistent with low- or no-cost generalism. Our results support major elements of the specialist-generalist theory, providing evidence of a specialist-generalist continuum in a vertebrate pathogen. These results also quantify within-host replicative fitness trade-offs resulting from the natural evolution of specialist and generalist virus lineages in multi-host ecosystems.
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Affiliation(s)
- David J Páez
- School of Aquatic and Fishery Sciences, The University of Washington, 1122 NE Boat St, Box 355020, Seattle, WA 98195, USA
- U.S. Geological Survey, Western Fisheries Research Center, Marrowstone Marine Field Station, 616 Marrowstone Point Road, Nordland, WA 98358, USA
| | - Douglas McKenney
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA 98115, USA
| | - Maureen K Purcell
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA 98115, USA
| | - Kerry A Naish
- School of Aquatic and Fishery Sciences, The University of Washington, 1122 NE Boat St, Box 355020, Seattle, WA 98195, USA
| | - Gael Kurath
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA 98115, USA
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Batts WN, Capps TR, Crosson LM, Powers RL, Breyta R, Purcell MK. Rapid Diagnostic Test to Detect and Discriminate Infectious Hematopoietic Necrosis Virus (IHNV) Genogroups U and M to Aid Management of Pacific Northwest Salmonid Populations. Animals (Basel) 2022; 12:ani12141761. [PMID: 35883308 PMCID: PMC9311590 DOI: 10.3390/ani12141761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 11/16/2022] Open
Abstract
Infectious hematopoietic necrosis virus (IHNV) is an acute pathogen of salmonids in North America, Europe, and Asia that is phylogenetically classified into five major virus genogroups (U, M, L, E, and J). The geographic range of the U and M genogroup isolates overlap in the North American Columbia River Basin and Washington Coast region, where these genogroups pose different risks depending on the species of Pacific salmon (Oncorhynchus spp.). For certain management decisions, there is a need to both test for IHNV presence and rapidly determine the genogroup. Herein, we report the development and validation of a U/M multiplex reverse transcription, real-time PCR (RT-rPCR) assay targeting the IHNV nucleocapsid (N) protein gene. The new U/M RT-rPCR is a rapid, sensitive, and repeatable assay capable of specifically discriminating between North American U and M genogroup IHNV isolates. However, one M genogroup isolate obtained from commercially cultured Idaho rainbow trout (O. mykiss) showed reduced sensitivity with the RT-rPCR test, suggesting caution may be warranted before applying RT-rPCR as the sole surveillance test in areas associated with the Idaho trout industry. The new U/M assay had high diagnostic sensitivity (DSe > 94%) and specificity (DSp > 97%) in free-ranging adult Pacific salmon, when assessed relative to cell culture, the widely accepted reference standard, as well as the previously validated universal N RT-rPCR test. The high diagnostic performance of the new U/M assay indicates the test is suitable for surveillance, diagnosis, and confirmation of IHNV in Pacific salmon from the Pacific Northwest regions where the U and M genogroups overlap.
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Affiliation(s)
- William N. Batts
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (W.N.B.); (R.L.P.)
| | - Tony R. Capps
- Washington Department of Fish and Wildlife, Olympia, WA 98501, USA; (T.R.C.); (L.M.C.)
| | - Lisa M. Crosson
- Washington Department of Fish and Wildlife, Olympia, WA 98501, USA; (T.R.C.); (L.M.C.)
| | - Rachel L. Powers
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (W.N.B.); (R.L.P.)
| | - Rachel Breyta
- School of Aquatic and Fisheries Sciences, University of Washington, Seattle, WA 98195, USA;
| | - Maureen K. Purcell
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (W.N.B.); (R.L.P.)
- Correspondence:
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Bendorf CM, Yun SC, Kurath G, Hedrick RP. Comparative Susceptibilities of Selected California Chinook Salmon and Steelhead Populations to Isolates of L Genogroup Infectious Hematopoietic Necrosis Virus (IHNV). Animals (Basel) 2022; 12:ani12131733. [PMID: 35804631 PMCID: PMC9264940 DOI: 10.3390/ani12131733] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/23/2022] [Accepted: 06/29/2022] [Indexed: 01/03/2023] Open
Abstract
Simple Summary Chinook salmon in California conservation hatcheries have suffered disease outbreaks and significant mortality due to the fish virus infectious hematopoietic necrosis virus (IHNV) since at least the 1940s. Although steelhead trout in California are also occasionally infected with the same virus they do not typically experience disease. In this study the susceptibility of California Chinook salmon and steelhead trout was defined in controlled experiments that exposed groups of juvenile fish to California IHNV strains (L genogroup). The results confirmed high mortality among Chinook salmon but very low mortality of steelhead trout, despite identical virus exposures. Tests of varying conditions found increasing mortality of Chinook salmon with increasing virus dose, but reduced mortality at higher temperatures or with increased age or size of fish. Among Chinook salmon that survived virus exposure the persistence of virus was detected in one fish 8 months after virus exposure. These findings demonstrate that L genogroup IHNV in California has host specificity for Chinook salmon, and provide an understanding of factors that contribute to disease epidemics in California hatchery Chinook salmon. Abstract Salmonid species demonstrate varied susceptibility to the viral pathogen infectious hematopoietic necrosis virus (IHNV). In California conservation hatcheries, juvenile Chinook salmon (Oncorhynchus tshawytscha) have experienced disease outbreaks due to L genogroup IHNV since the 1940s, while indigenous steelhead (anadromous O. mykiss) appear relatively resistant. To characterize factors contributing to the losses of California salmonid fish due to IHNV, three populations of Chinook salmon and two populations of steelhead native to California watersheds were compared in controlled waterborne challenges with California L genogroup IHNV isolates at viral doses of 104–106 pfu mL−1. Chinook salmon fry were moderately to highly susceptible (CPM = 47–87%) when exposed to subgroup LI and LII IHNV. Susceptibility to mortality decreased with increasing age and also with a higher temperature. Mortality for steelhead fry exposed to two IHNV isolates was low (CPM = 1.3–33%). There was little intraspecies variation in susceptibility among populations of Chinook salmon and no differences in virulence between viruses strains. Viral persistence was demonstrated by the isolation of low levels of infectious IHNV from the skin of two juvenile Chinook salmon at 215 d post exposure. The persistence of the virus among Chinook salmon used for stocking into Lake Oroville may be an explanation for the severe epidemics of IHN at the Feather River hatchery in 1998–2002.
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Affiliation(s)
- Christin M. Bendorf
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; (C.M.B.); (S.C.Y.); (R.P.H.)
- Department of Biological Sciences, California State University, Sacramento, CA 95819, USA
| | - Susan C. Yun
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; (C.M.B.); (S.C.Y.); (R.P.H.)
| | - Gael Kurath
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115, USA
- Correspondence:
| | - Ronald P. Hedrick
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA; (C.M.B.); (S.C.Y.); (R.P.H.)
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Bledsoe JW, Ma J, Cain K, Bruce TJ, Rawles A, Abernathy J, Welker T, Overturf K. Multi-tissue RNAseq reveals genetic and temporal differences in acute response to viral (IHNV) infection among three selected lines of rainbow trout with varying resistance. FISH & SHELLFISH IMMUNOLOGY 2022; 124:343-361. [PMID: 35398222 DOI: 10.1016/j.fsi.2022.03.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
Utilizing RNA-seq, this study compared the transcriptomic responses of three improved strains (VSel, PSel, and CSel) of rainbow trout fry during acute stages of challenge with infectious hematopoietic necrosis virus (IHNV). The VSel strain has been selected for resistance against the specific strain of IHNV used in our challenge, PSel has undergone selection for utilization of plant-protein based feeds and previously has shown elevated non-specific disease resistance despite no disease related selection pressures, and the final strain, CSel, is a commercial strain that has been domesticated for several years but has not been selected for specific viral disease resistance. Following a 21-day IHNV challenge, Kaplan-Meier survival estimator curves and cumulative percent mortality (CPM) showed significant differences in IHNV resistance across strains: VSel - 19.3 ± 5.0%, PSel - 67. ± 3.03%, CSel - 94.6 ± 4.1% CPM. To evaluate acute responses to IHNV infection, whole blood, as well as samples from the kidney, liver, and intestine, were collected at 0, 4, 12, 24, and 48 h post infection (hpi). Serum lysozyme activity, a marker of non-specific innate immunity, showed strain and temporal effects during the acute infection phase with PSel showing the highest activity at 0 and 48 hpi. Differential gene expression responses were detected, with varying degrees, in all tissues, both between strains, as well as across acute timepoints within strains. The VSel strain showed upregulation for a particular subset of viral recognition genes during early infection timepoints and rather limited upregulation of immune genes later, while maintaining and reactivating metabolic pathways. The CSel strain showed a downregulation of metabolic related genes and a limited upregulation of immune genes, while the PSel strain showed similar downregulation of metabolic genes during acute infection, yet when compared to the CSel strain, showed a more robust innate immune response. Evaluation of upregulated immune response genes, as well as interferon-related genes showed the PSel strain to have the greatest number of uniquely upregulated immune genes in both the kidney and intestine, with CSel and PSel showing a similar number of such genes upregulated in liver. A moderate number of immune response genes were shared between PSel and CSel in all tissues, though both PSel and VSel showed a high number of uniquely overexpressed immune response genes in the kidney, and PSel showed the highest number of uniquely upregulated interferon related genes in the intestine. Overall, the VSel response was unique from the CSel with very little overlap in activated immune responses. Findings from this study highlight the disparity in IHNV resistance among genetic strains of rainbow trout, while identifying molecular mechanisms underlying differences in disease phenotypes. Furthermore, our results on trout strains with distinct selection backgrounds yields comparative insights into the adaptive gains brought about by selection programs for pathogen-specific disease resistance, as well as the non-specific immune enhancement associated with selection for utilization of plant-based diets.
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Affiliation(s)
- Jacob W Bledsoe
- Aquaculture Research Institute, Department of Animal, Veterinary & Food Sciences, University of Idaho, Hagerman, ID, USA
| | - Jia Ma
- Department of Fish and Wildlife Sciences, University of Idaho, Moscow, ID, USA
| | - Ken Cain
- Department of Fish and Wildlife Sciences, University of Idaho, Moscow, ID, USA
| | - Timothy J Bruce
- School of Fisheries, Aquaculture & Aquatic Sciences, Auburn University, Auburn, AL, USA
| | - Anna Rawles
- ARS-USDA, Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, AR, USA
| | - Jason Abernathy
- ARS-USDA, Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, AR, USA
| | - Tom Welker
- United States Department of Agriculture-Agricultural Research Service, Hagerman Fish Culture Experiment Station, Hagerman, ID, USA
| | - Ken Overturf
- United States Department of Agriculture-Agricultural Research Service, Hagerman Fish Culture Experiment Station, Hagerman, ID, USA.
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Emmenegger EJ, Bueren EK, Jia P, Hendrix N, Liu H. Comparative virulence of spring viremia of carp virus (SVCV) genotypes in two koi varieties. DISEASES OF AQUATIC ORGANISMS 2022; 148:95-112. [PMID: 35297379 DOI: 10.3354/dao03650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Spring viremia of carp virus (SVCV), is a lethal freshwater pathogen of cyprinid fish, and Cyprinus carpio koi is a primary host species. The virus was initially described in the 1960s after outbreaks occurred in Europe, but a global expansion of SVCV has been ongoing since the late 1990s. Genetic typing of SVCV isolates separates them into 4 genotypes that are correlated with geographic origin: Ia (Asia), Ib and Ic (Eastern Europe), and Id (Central Europe). We compared infectivity and virulence of 8 SVCV strains, including 4 uncharacterized Chinese Ia isolates and representatives of genotypes Ia-d in 2 morphologically distinct varieties of koi: long-fin semi-scaled Beni Kikokuryu koi and short-fin fully scaled Sanke koi. Mortality ranged from 4 to 82% in the Beni Kikokuryu koi and 0 to 94% in the Sanke koi following immersion challenge. Genotype Ia isolates of Asian origin had a wide range in virulence (0-94%). Single isolates representing the European genotypes Ib and Ic were moderately virulent (38-56%). Each virus strain produced similar levels of mortality in both koi breeds, with the exception of the SVCV Id strain that appeared to have both moderate and high virulence phenotypes (60% in Beni Kikokuryu koi vs. 87% in Sanke koi). Overall SVCV strain virulence appeared to be a dominant factor in determining disease outcomes, whereas intraspecies variation, based on koi variety, had less of an impact. This study is the first side-by-side comparison of Chinese SVCV isolates and genotype Ia-d strain virulence in a highly susceptible host.
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10
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Shen M, Jiang Z, Zhang K, Li C, Liu F, Hu Y, Zheng S, Zheng R. Transcriptome analysis of grass carp (Ctenopharyngodon idella) and Holland's spinibarbel (Spinibarbus hollandi) infected with Ichthyophthirius multifiliis. FISH & SHELLFISH IMMUNOLOGY 2022; 121:305-315. [PMID: 35031476 DOI: 10.1016/j.fsi.2022.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 12/23/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Ichthyophthirius multifiliis is a protozoan ciliate that causes white spot disease (also known as ichthyophthiriasis) in freshwater fish. Holland's spinibarbel (Spinibarbus hollandi) was less susceptible to white spot disease than grass carp (Ctenopharyngodon Idella). In this study, grass carp and Holland's spinibarbel are infected by I. multifiliis and the amount of infection is 10,000 theronts per fish. All grass carp died within 12 days after infection, and the survival rate of Holland's spinibarbel was more than 80%. In order to study the difference in sensitivity of these two fish species to I. multifiliis, transcriptome analysis was conducted using gill, skin, liver, spleen and head kidney of Holland's spinibarbel and grass carp at 48 h post-infection with I. multifiliis. A total of 489,296,696 clean reads were obtained by sequencing. A total of 105 significantly up-regulated immune-related genes were obtained by Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis in grass carp. Cluster of differentiation 40 (CD40), cluster of differentiation 80 (CD 80), tumor necrosis factor-alpha (TNF-α), toll-like receptor 4 (TLR-4), interleukin 1 beta (IL-1β) and other inflammatory-related genes in grass carp were enriched in the cytokine-cytokine receptor interaction pathway and toll-like receptor pathway. In Holland's spinibarbel, a total of 46 significantly up-regulated immune-related genes were obtained by GO classification and KEGG pathway enrichment analysis. Immune-related genes, such as Immunoglobin heavy chain (IgH), cathepsin S (CTSS), complement C1q A chain (C1qA), complement component 3 (C3) and complement component (C9) were enriched in phagosome pathway, lysosome pathway and complement and coagulation concatenation pathway. C3 was significantly up-regulated in gill and head kidney. Fluorescence in situ hybridization (FISH) showed that the C3 gene was highly expressed in gill tissue of Holland's spinibarbel infected with I. multifiliis. A small amount of C3 gene was expressed in the gill arch of grass carp after infected with I. multifiliis. In conclusion, the severe inflammatory response in vivo after infecting grass carp with I. multifiliis might be the main cause of the death of grass carp. The extrahepatic expression of the gene of Holland's spinibarbel might play an important role in the immune defense against I. multifiliis.
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Affiliation(s)
- Minghao Shen
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China.
| | - Zeyuan Jiang
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China.
| | - Kai Zhang
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China.
| | - Chenyang Li
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China.
| | - Fangling Liu
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China.
| | - Yibing Hu
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China.
| | - Shanjian Zheng
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China.
| | - Rongquan Zheng
- College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, China; Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, Jinhua, 321004, China; Xinzhi College, Zhejiang Normal University, Jinhua, 321004, China.
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Kim SS, Kim KI, Yoo HK, Han YS, Jegal ME, Byun SG, Lim HJ, Park JS, Kim YJ. Differential virulence of infectious hematopoietic necrosis virus (IHNV) isolated from salmonid fish in Gangwon Province, Korea. FISH & SHELLFISH IMMUNOLOGY 2021; 119:490-498. [PMID: 34715327 DOI: 10.1016/j.fsi.2021.10.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 10/01/2021] [Accepted: 10/24/2021] [Indexed: 06/13/2023]
Abstract
The present study investigated the virulence and expression of innate immunity genes in isolates of infectious hematopoietic necrosis virus (IHNV) in Gangwon province, South Korea, by challenging rainbow trout, Atlantic salmon, and coho salmon. Eight IHNV isolates were used to infect RTG-2 cells for viral replication using plaque assays. Three isolates with the highest replication rates, the RtPc0314g and RtPc0314c isolates of the JRt-Shizuoka type and the RtPc0816g isolate of the JRt-Nagano type, were experimentally infected into the fish. In rainbow trout, both RtPc0314c and RtPc0314g isolates showed 100% cumulative mortality while the RtPc0816g isolate showed 60% cumulative mortality for 14 days. In contrast, all three isolates showed <60% cumulative mortality in Atlantic salmon and coho salmon. The expression of G genes in the kidney was higher than that in the spleen-infected fish, with the highest expression observed in the kidneys of rainbow trout. The relative expression levels of innate immunity genes were higher in rainbow trout than in Atlantic salmon and coho salmon. The expression level of immunoglobulin M increased until day 7, and the expression of type I interferon was higher in the spleen than in other tissues. The expression of Mx-1 was higher in the kidney and liver than other tissues. These results indicate that IHNV isolates from Gangwon province show host-specific virulence in rainbow trout and that their virulence and replication were higher in JRt-Shizuoka type than in JRt-Nagano type isolates.
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Affiliation(s)
- So-Sun Kim
- East Sea Fisheries Research Institute, National Institute of Fisheries Science, Gangneung-si, 25435, Republic of Korea; Department of Molecular Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Kwang-Il Kim
- Department of Aquatic Life Medicine, Pukyoung National University, Busan, 48513, Republic of Korea
| | - Hae-Kyun Yoo
- East Sea Fisheries Research Institute, National Institute of Fisheries Science, Gangneung-si, 25435, Republic of Korea
| | - Yu-Seon Han
- Department of Molecular Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Myeong-Eun Jegal
- Department of Molecular Biology, Pusan National University, Busan, 46241, Republic of Korea
| | - Soon-Gyu Byun
- East Sea Fisheries Research Institute, National Institute of Fisheries Science, Gangneung-si, 25435, Republic of Korea
| | - Hyun-Jeong Lim
- Southeast Sea Fisheries Research Institute, National Institute of Fisheries Science, Tongyeong, Republic of Korea
| | - Jang-Su Park
- Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan, 46241, Republic of Korea
| | - Yung-Jin Kim
- Department of Molecular Biology, Pusan National University, Busan, 46241, Republic of Korea.
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12
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Abbadi M, Gastaldelli M, Pascoli F, Zamperin G, Buratin A, Bedendo G, Toffan A, Panzarin V. Increased virulence of Italian infectious hematopoietic necrosis virus (IHNV) associated with the emergence of new strains. Virus Evol 2021; 7:veab056. [PMID: 34754510 PMCID: PMC8570149 DOI: 10.1093/ve/veab056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/30/2021] [Accepted: 06/07/2021] [Indexed: 12/26/2022] Open
Abstract
Infectious hematopoietic necrosis virus (IHNV) is the causative agent of IHN triggering a systemic syndrome in salmonid fish. Although IHNV has always been associated with low levels of mortality in Italian trout farming industries, in the last years trout farmers have experienced severe disease outbreaks. However, the observed increasing virulence of IHNV is still based on empirical evidence due to the poor and often confounding information from the field. Virulence characterization of a selection of sixteen Italian isolates was performed through in vivo challenge of juvenile rainbow trout to confirm field evidence. The virulence of each strain was firstly described in terms of cumulative mortality and survival probability estimated by Kaplan-Meier curves. Furthermore, parametric survival models were applied to analyze the mortality rate profiles. Hence, it was possible to characterize the strain-specific mortality peaks and to relate their topology to virulence and mortality. Indeed, a positive correlation between maximum mortality probability and virulence was observed for all the strains. Results also indicate that more virulent is the strain, the earliest and narrowest is the mortality peak. Additionally, intra-host viral quantification determined in dead animals showed a significant correlation between viral replication and virulence. Whole-genome phylogeny conducted to determine whether there was a relation between virulence phenotype and IHNV genetics evidenced no clear clustering according to phenotype. Moreover, a root-to-tip analysis based on genetic distances and sampling date of Italian IHNV isolates highlighted a relevant temporal signal indicating an evolving nature of the virus, over time, with the more virulent strains being the more recent ones. This study provides the first systematic characterization of Italian IHNV's virulence. Overall results confirm field data and point out an abrupt increase in IHNV virulence, with strains from 2015-2019 showing moderate to high virulence in rainbow trout. Further investigations are needed in order to extensively clarify the relation between evolution and virulence of IHNV and investigate the genetic determinants of virulence of this viral species in rainbow trout.
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Affiliation(s)
- Miriam Abbadi
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
| | - Michele Gastaldelli
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
| | - Francesco Pascoli
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
| | - Gianpiero Zamperin
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
| | - Alessandra Buratin
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
| | - Giulia Bedendo
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
| | - Anna Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
| | - Valentina Panzarin
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, 35020, Legnaro, Padova, Italy
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13
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Ito T, Kamaishi T. Japanese amberjack Seriola quinqueradiata and red sea bream Pagrus major susceptibility to infectious hematopoietic necrosis virus (IHNV) isolate. DISEASES OF AQUATIC ORGANISMS 2021; 146:1-8. [PMID: 34382581 DOI: 10.3354/dao03615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Infectious hematopoietic necrosis virus (IHNV) is known as a causative agent of heavy mortalities in farmed rainbow trout. However, there is limited information on its virulence for marine fish species. In this study, Japanese amberjack Seriola quinqueradiata and red sea bream Pagrus major were experimentally infected by intraperitoneal (IP) injection and immersion, with an IHNV isolate from rainbow trout in Japan, to evaluate the virulence of the virus for these fish species. The cumulative mortality for immersed rainbow trout was 15%. IHNV was isolated from all dead fish and 50% of the sequentially sampled rainbow trout. When Japanese amberjack were challenged by IP injection and immersion, the resulting cumulative mortality was 70% and 0%, respectively. The virus was isolated from all dead fish and 1 out of 3 Japanese amberjack sampled at 9 d post exposure. However, no mortality was observed in either of the red sea bream groups challenged with IHNV. IHNV was not isolated from any of the surviving red sea bream, or from any of the sequentially sampled fish. The viral titer on Japanese amberjack-derived YTF cells was in the same log range as that on FHM and RTH-149 cells, but the titers on the red sea bream cell lines SBK and GBRS were lower than the other cell lines, and were significantly different from the FHM and RTH-149 cell lines. These results suggest that Japanese amberjack has a low susceptibility to IHNV, and red sea bream has no or little susceptibility to the virus.
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Affiliation(s)
- Takafumi Ito
- Pathology Division, Fisheries Technology Institute, Fisheries Research Agency, 422-1, Nakatsuhamaura, Minami-Ise, Mie 516-0193, Japan
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14
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Páez DJ, Powers RL, Jia P, Ballesteros N, Kurath G, Naish KA, Purcell MK. Temperature Variation and Host Immunity Regulate Viral Persistence in a Salmonid Host. Pathogens 2021; 10:855. [PMID: 34358005 PMCID: PMC8308775 DOI: 10.3390/pathogens10070855] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 06/15/2021] [Accepted: 06/23/2021] [Indexed: 11/17/2022] Open
Abstract
Environmental variation has important effects on host-pathogen interactions, affecting large-scale ecological processes such as the severity and frequency of epidemics. However, less is known about how the environment interacts with host immunity to modulate virus fitness within hosts. Here, we studied the interaction between host immune responses and water temperature on the long-term persistence of a model vertebrate virus, infectious hematopoietic necrosis virus (IHNV) in steelhead trout (Oncorhynchus mykiss). We first used cell culture methods to factor out strong host immune responses, allowing us to test the effect of temperature on viral replication. We found that 15 ∘C water temperature accelerated IHNV replication compared to the colder 10 and 8 ∘C temperatures. We then conducted in vivo experiments to quantify the effect of 6, 10, and 15 ∘C water temperatures on IHNV persistence over 8 months. Fish held at 15 and 10 ∘C were found to have higher prevalence of neutralizing antibodies compared to fish held at 6 ∘C. We found that IHNV persisted for a shorter time at warmer temperatures and resulted in an overall lower fish mortality compared to colder temperatures. These results support the hypothesis that temperature and host immune responses interact to modulate virus persistence within hosts. When immune responses were minimized (i.e., in vitro) virus replication was higher at warmer temperatures. However, with a full potential for host immune responses (i.e., in vivo experiments) longer virus persistence and higher long-term virulence was favored in colder temperatures. We also found that the viral RNA that persisted at later time points (179 and 270 days post-exposure) was mostly localized in the kidney and spleen tissues. These tissues are composed of hematopoietic cells that are favored targets of the virus. By partitioning the effect of temperature on host and pathogen responses, our results help to better understand environmental drivers of host-pathogen interactions within hosts, providing insights into potential host-pathogen responses to climate change.
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Affiliation(s)
- David J. Páez
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA;
| | - Rachel L. Powers
- US Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (R.L.P.); (P.J.); (N.B.); (G.K.)
| | - Peng Jia
- US Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (R.L.P.); (P.J.); (N.B.); (G.K.)
- Shenzhen Customs, Animal & Plant Inspection and Quarantine Technology Center, Shenzhen 518045, China
- Quality and Standards Academy, Shenzhen Technology University, Shenzhen 518118, China
| | - Natalia Ballesteros
- US Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (R.L.P.); (P.J.); (N.B.); (G.K.)
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Gael Kurath
- US Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (R.L.P.); (P.J.); (N.B.); (G.K.)
| | - Kerry A. Naish
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA;
| | - Maureen K. Purcell
- US Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA; (R.L.P.); (P.J.); (N.B.); (G.K.)
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15
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Wargo AR, Kurath G, Scott RJ, Kerr B. Virus shedding kinetics and unconventional virulence tradeoffs. PLoS Pathog 2021; 17:e1009528. [PMID: 33970967 PMCID: PMC8109835 DOI: 10.1371/journal.ppat.1009528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/03/2021] [Indexed: 11/19/2022] Open
Abstract
Tradeoff theory, which postulates that virulence provides both transmission costs and benefits for pathogens, has become widely adopted by the scientific community. Although theoretical literature exploring virulence-tradeoffs is vast, empirical studies validating various assumptions still remain sparse. In particular, truncation of transmission duration as a cost of virulence has been difficult to quantify with robust controlled in vivo studies. We sought to fill this knowledge gap by investigating how transmission rate and duration were associated with virulence for infectious hematopoietic necrosis virus (IHNV) in rainbow trout (Oncorhynchus mykiss). Using host mortality to quantify virulence and viral shedding to quantify transmission, we found that IHNV did not conform to classical tradeoff theory. More virulent genotypes of the virus were found to have longer transmission durations due to lower recovery rates of infected hosts, but the relationship was not saturating as assumed by tradeoff theory. Furthermore, the impact of host mortality on limiting transmission duration was minimal and greatly outweighed by recovery. Transmission rate differences between high and low virulence genotypes were also small and inconsistent. Ultimately, more virulent genotypes were found to have the overall fitness advantage, and there was no apparent constraint on the evolution of increased virulence for IHNV. However, using a mathematical model parameterized with experimental data, it was found that host culling resurrected the virulence tradeoff and provided low virulence genotypes with the advantage. Human-induced or natural culling, as well as host population fragmentation, may be some of the mechanisms by which virulence diversity is maintained in nature. This work highlights the importance of considering non-classical virulence tradeoffs.
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Affiliation(s)
- Andrew R. Wargo
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, United States of America
| | - Gael Kurath
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, Washington, United States of America
| | - Robert J. Scott
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Benjamin Kerr
- Department of Biology, University of Washington, Seattle, Washington, United States of America
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Hernandez DG, Brown W, Naish KA, Kurath G. Virulence and Infectivity of UC, MD, and L Strains of Infectious Hematopoietic Necrosis Virus (IHNV) in Four Populations of Columbia River Basin Chinook Salmon. Viruses 2021; 13:v13040701. [PMID: 33919549 PMCID: PMC8072589 DOI: 10.3390/v13040701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/10/2021] [Accepted: 04/14/2021] [Indexed: 12/31/2022] Open
Abstract
Infectious Hematopoietic Necrosis Virus (IHNV) infects juvenile salmonid fish in conservation hatcheries and aquaculture facilities, and in some cases, causes lethal disease. This study assesses intra-specific variation in the IHNV susceptibility of Chinook salmon (Oncorhynchus tshawytscha) in the Columbia River Basin (CRB), in the northwestern United States. The virulence and infectivity of IHNV strains from three divergent virus genogroups are measured in four Chinook salmon populations, including spring-run and fall-run fish from the lower or upper regions of the CRB. Following controlled laboratory exposures, our results show that the positive control L strain had significantly higher virulence, and the UC and MD strains that predominate in the CRB had equivalently low virulence, consistent with field observations. By several experimental measures, there was little variation in host susceptibility to infection or disease. However, a small number of exceptions suggested that the lower CRB spring-run Chinook salmon population may be less susceptible than other populations tested. The UC and MD viruses did not differ in infectivity, indicating that the observed asymmetric field prevalence in which IHNV detected in CRB Chinook salmon is 83% UC and 17% MD is not due to the UC virus being more infectious. Overall, we report little intra-species variation in CRB Chinook salmon susceptibility to UC or MD IHNV infection or disease, and suggest that other factors may instead influence the ecology of IHNV in the CRB.
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Affiliation(s)
- Daniel G. Hernandez
- Western Fisheries Research Center, United States Geological Survey, Seattle, WA 98115, USA;
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA;
| | - William Brown
- Department of Statistics, University of Washington, Seattle, WA 98195, USA;
| | - Kerry A. Naish
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA;
| | - Gael Kurath
- Western Fisheries Research Center, United States Geological Survey, Seattle, WA 98115, USA;
- Correspondence:
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17
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Kim J, Cho M, Kim KI, Min EY, Lim J, Hong S. Transcriptome profiling in head kidney of rainbow trout (Oncorhynchus mykiss) after infection with the low-virulent Nagano genotype of infectious hematopoietic necrosis virus. Arch Virol 2021; 166:1057-1070. [PMID: 33532870 DOI: 10.1007/s00705-021-04980-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 01/15/2021] [Indexed: 12/30/2022]
Abstract
Infectious hematopoietic necrosis virus (IHNV) causes clinical diseases and mortality in a wide variety of salmonid species. Here, we studied transcriptional responses in rainbow trout infected by the IHNV-Nagano strain isolated in Korea. RNA-seq-based transcriptome analysis of head kidney tissues cataloged differentially expressed genes. Enrichment analysis of gene ontology annotations was performed, and a total of fifteen biological process terms were commonly identified at all time points. In the Kyoto Encyclopedia of Genes and Genomes pathway analysis, pathogen recognition receptor (PRR) signaling pathways such as the retinoic-acid-inducible gene-I-like receptor signaling pathway and the Toll-like receptor signaling pathway were identified at all time points. The nucleotide-binding oligomerization-domain-like receptor signaling pathway and cytosolic DNA-sensing pathway were identified at days 1 and 3. Protein-protein interaction network and centrality analyses revealed that the immune system, signaling molecules, and interaction pathways were upregulated at days 1 and 3, with the highest centrality of tumor necrosis factor. Cancer, cellular community, and endocrine system pathways were downregulated, with the highest centrality of fibronectin 1 at day 5. STAT1 was upregulated from days 1 to 5 with a high centrality. The reproducibility and repeatability of the transcriptome analysis were validated by RT-qPCR. IHNV-Nagano infection dynamically changed the transcriptome profiles in the head kidney of rainbow trout and induced a defense mechanism by regulating the immune and inflammatory pathways through PRR signaling at an early stage. Downregulated pathways involved in extracellular matrix formation and focal adhesion at day 5 indicated the possible failure of wound healing, which is important in the pathogenesis of IHNV infection.
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Affiliation(s)
- Jinwoo Kim
- Department of Marine Biotechnology, Gangneung-Wonju National University, Gangneung, 210-702, Korea
| | - Miyoung Cho
- Pathology Research Division, National Institute of Fisheries Science, Busan, Korea
| | - Kwang Il Kim
- Pathology Research Division, National Institute of Fisheries Science, Busan, Korea
| | - Eun Young Min
- Pathology Research Division, National Institute of Fisheries Science, Busan, Korea
| | - Jongwon Lim
- Department of Marine Biotechnology, Gangneung-Wonju National University, Gangneung, 210-702, Korea
| | - Suhee Hong
- Department of Marine Biotechnology, Gangneung-Wonju National University, Gangneung, 210-702, Korea.
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Hwang JY, Lee UH, Heo MJ, Kim MS, Jeong JM, Kim SY, Kwon MG, Jee BY, Kim KH, Park CI, Park JW. Naturally occurring substitution in one amino acid in VHSV phosphoprotein enhances viral virulence in flounder. PLoS Pathog 2021; 17:e1009213. [PMID: 33465148 PMCID: PMC7845975 DOI: 10.1371/journal.ppat.1009213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 01/29/2021] [Accepted: 12/03/2020] [Indexed: 12/24/2022] Open
Abstract
Viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus that causes high mortality in cultured flounder. Naturally occurring VHSV strains vary greatly in virulence. Until now, little has been known about genetic alterations that affect the virulence of VHSV in flounder. We recently reported the full-genome sequences of 18 VHSV strains. In this study, we determined the virulence of these 18 VHSV strains in flounder and then the assessed relationships between differences in the amino acid sequences of the 18 VHSV strains and their virulence to flounder. We identified one amino acid substitution in the phosphoprotein (P) (Pro55-to-Leu substitution in the P protein; PP55L) that is specific to highly virulent strains. This PP55L substitution was maintained stably after 30 cell passages. To investigate the effects of the PP55L substitution on VHSV virulence in flounder, we generated a recombinant VHSV carrying PP55L (rVHSV-P) from rVHSV carrying P55 in the P protein (rVHSV-wild). The rVHSV-P produced high level of viral RNA in cells and showed increased growth in cultured cells and virulence in flounder compared to the rVHSV-wild. In addition, rVHSV-P significantly inhibited the induction of the IFN1 gene in both cells and fish at 6 h post-infection. An RNA-seq analysis confirmed that rVHSV-P infection blocked the induction of several IFN-related genes in virus-infected cells at 6 h post-infection compared to rVHSV-wild. Ectopic expression of PP55L protein resulted in a decrease in IFN induction and an increase in viral RNA synthesis in rVHSV-wild-infected cells. Taken together, our results are the first to identify that the P55L substitution in the P protein enhances VHSV virulence in flounder. The data from this study add to the knowledge of VHSV virulence in flounder and could benefit VHSV surveillance efforts and the generation of a VHSV vaccine. Viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus that causes huge economic losses to the fish culture industry throughout the world. Virulence among naturally occurring VHSV strains varies widely. However, little is known about the viral factors that determine VHSV virulence. Here, we identify a naturally-occurring, single-amino-acid substitution in the VHSV P protein that enhances VHSV virulence in flounder. This amino acid substitution in the P protein was detected only in highly virulent VHSV strains, and it enhances viral RNA synthesis and inhibits the interferon response of host cells early after virus infection. Recombinant VHSV containing this amino acid substitution caused increased mortality in flounder compared with the wild type. This is the first study to identify a naturally occurring amino acid substitution in VHSV that determines its virulence in flounder. We expect that our result can be applied to other fish species, and this finding will provide new opportunities to generate an effective VHSV vaccine.
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Affiliation(s)
- Jee Youn Hwang
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, Korea
| | - Unn Hwa Lee
- Department of Biological Sciences, University of Ulsan, Ulsan, Korea
| | - Min Jin Heo
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, Gyeongnam, Korea
| | - Min Sun Kim
- Department of Integrative Bio-industrial Engineering, Sejong University, Seoul, Korea
| | - Ji Min Jeong
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, Korea
| | - So Yeon Kim
- Department of Aquatic Life Medicine, Pukyong National University, Busan, Korea
| | - Mun Gyeong Kwon
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, Korea
| | - Bo Young Jee
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, Korea
| | - Ki Hong Kim
- Department of Aquatic Life Medicine, Pukyong National University, Busan, Korea
- * E-mail: (KHK); (CIP); (JWP)
| | - Chan-Il Park
- Department of Marine Biology & Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, Gyeongnam, Korea
- * E-mail: (KHK); (CIP); (JWP)
| | - Jeong Woo Park
- Department of Biological Sciences, University of Ulsan, Ulsan, Korea
- * E-mail: (KHK); (CIP); (JWP)
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Louboutin L, Cabon J, Vigouroux E, Morin T, Danion M. Comparative analysis of the course of infection and the immune response in rainbow trout (Oncorhynchus mykiss) infected with the 5 genotypes of infectious hematopoietic necrosis virus. Virology 2021; 552:20-31. [DOI: 10.1016/j.virol.2020.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 09/03/2020] [Accepted: 09/03/2020] [Indexed: 12/29/2022]
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20
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López-Vázquez C, Bandín I, Panzarin V, Toffan A, Cuenca A, Olesen NJ, Dopazo CP. Steps of the Replication Cycle of the Viral Haemorrhagic Septicaemia Virus (VHSV) Affecting Its Virulence on Fish. Animals (Basel) 2020; 10:E2264. [PMID: 33271890 PMCID: PMC7761041 DOI: 10.3390/ani10122264] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/26/2020] [Accepted: 11/26/2020] [Indexed: 12/14/2022] Open
Abstract
The viral haemorrhagic septicaemia virus (VHSV), a single-stranded negative-sense RNA novirhabdovirus affecting a wide range of marine and freshwater fish species, is a main concern for European rainbow trout (Oncorhynchus mykiss) fish farmers. Its genome is constituted by six genes, codifying five structural and one nonstructural proteins. Many studies have been carried out to determine the participation of each gene in the VHSV virulence, most of them based on genome sequence analysis and/or reverse genetics to construct specific mutants and to evaluate their virulence phenotype. In the present study, we have used a different approach with a similar aim: hypothesizing that a failure in any step of the replication cycle can reduce the virulence in vivo, we studied in depth the in vitro replication of VHSV in different cell lines, using sets of strains from different origins, with high, low and moderate levels of virulence for fish. The results demonstrated that several steps in the viral replication cycle could affect VHSV virulence in fish, including adsorption, RNA synthesis and morphogenesis (including viral release). Notably, differences among strains in any step of the replication cycle were mostly strain-specific and reflected only in part the in vivo phenotype (high and low virulent). Our data, therefore, support the need for further studies aimed to construct completely avirulent VHSV recombinants targeting a combination of genes rather than a single one in order to study the mechanisms of genes interplay and their effect on viral phenotype in vitro and in vivo.
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Affiliation(s)
- Carmen López-Vázquez
- Instituto de Acuicultura-Dpt Microbiología, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (C.L.-V.); (I.B.)
| | - Isabel Bandín
- Instituto de Acuicultura-Dpt Microbiología, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (C.L.-V.); (I.B.)
| | - Valentina Panzarin
- Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, viale dell’Università 10, 35020 Legnaro, Padova, Italy; (V.P.); (A.T.)
| | - Anna Toffan
- Department of Comparative Biomedical Sciences, Istituto Zooprofilattico Sperimentale delle Venezie, viale dell’Università 10, 35020 Legnaro, Padova, Italy; (V.P.); (A.T.)
| | - Argelia Cuenca
- Unit for Fish and Shellfish Diseases, National Institute of Aquatic Resources, Technical University of Denmark, Kemitorvet 202, 2800 Kgs Lyngby, Denmark; (A.C.); (N.J.O.)
| | - Niels J. Olesen
- Unit for Fish and Shellfish Diseases, National Institute of Aquatic Resources, Technical University of Denmark, Kemitorvet 202, 2800 Kgs Lyngby, Denmark; (A.C.); (N.J.O.)
| | - Carlos P. Dopazo
- Instituto de Acuicultura-Dpt Microbiología, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain; (C.L.-V.); (I.B.)
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21
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Hwang JY, Lee UH, Heo MJ, Jeong JM, Kwon MG, Jee BY, Park CI, Park JW. RNA-seq transcriptome analysis in flounder cells to compare innate immune responses to low- and high-virulence viral hemorrhagic septicemia virus. Arch Virol 2020; 166:191-206. [PMID: 33145636 DOI: 10.1007/s00705-020-04871-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Viral hemorrhagic septicemia virus (VHSV) is a rhabdovirus that causes high mortality in cultured flounder. Viral growth and virulence rely on the ability to inhibit the cellular innate immune response. In this study, we investigated differences in the modulation of innate immune responses of HINAE flounder cells infected with low- and high-virulence VHSV strains at a multiplicity of infection of 1 for 12 h and 24 h and performed RNA sequencing (RNA-seq)-based transcriptome analysis. A total of 193 and 170 innate immune response genes were differentially expressed by the two VHSV strains at 12 and 24 h postinfection (hpi), respectively. Of these, 73 and 77 genes showed more than a twofold change in their expression at 12 and 24 hpi, respectively. Of the genes with more than twofold changes, 22 and 11 genes showed high-virulence VHSV specificity at 12 and 24 hpi, respectively. In particular, IL-16 levels were more than two time higher and CCL20a.3, CCR6b, CCL36.1, Casp8L2, CCR7, and Trim46 levels were more than two times lower in high-virulence-VHSV-infected cells than in low-virulence-VHSV-infected cells at both 12 and 24 hpi. Quantitative PCR (qRT-PCR) confirmed the changes in expression of the ten mRNAs with the most significantly altered expression. This is the first study describing the genome-wide analysis of the innate immune response in VHSV-infected flounder cells, and we have identified innate immune response genes that are specific to a high-virulence VHSV strain. The data from this study can contribute to a greater understanding of the molecular basis of VHSV virulence in flounder.
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Affiliation(s)
- Jee Youn Hwang
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, 46083, Korea
| | - Unn Hwa Lee
- Department of Biological Sciences, University of Ulsan, Ulsan, 44610, Korea
| | - Min Jin Heo
- Department of Marine Biology and Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, Gyeongnam, 650-160, Korea
| | - Ji Min Jeong
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, 46083, Korea
| | - Mun Gyeong Kwon
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, 46083, Korea
| | - Bo Young Jee
- Aquatic Disease Control Division, National Institute Fisheries Science, Busan, 46083, Korea
| | - Chan-Il Park
- Department of Marine Biology and Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, Gyeongnam, 650-160, Korea.
| | - Jeong Woo Park
- Department of Biological Sciences, University of Ulsan, Ulsan, 44610, Korea.
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Kim KI, Lee UH, Cho M, Jung SH, Min EY, Park JW. Transcriptome analysis based on RNA-seq of common innate immune responses of flounder cells to IHNV, VHSV, and HIRRV. PLoS One 2020; 15:e0239925. [PMID: 32986779 PMCID: PMC7521715 DOI: 10.1371/journal.pone.0239925] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/15/2020] [Indexed: 12/25/2022] Open
Abstract
Viral hemorrhagic septicemia virus (VHSV) and hirame rhabdovirus (HIRRV) belong to the genus Novirhabdovirus and are the causative agents of a serious disease in cultured flounder. However, infectious hematopoietic necrosis virus (IHNV), a prototype of the genus Novirhabdovirus, does not cause disease in flounder. To determine whether IHNV growth is restricted in flounder cells, we compared the growth of IHNV with that of VHSV and HIRRV in hirame natural embryo (HINAE) cells infected with novirhabdoviruses at 1 multiplicity of infection. Unexpectedly, we found that IHNV grew as well as VHSV and HIRRV. For successful growth in host cells, viruses modulate innate immune responses exerted by virus-infected cells. Our results suggest that IHNV, like VHSV and HIRRV, has evolved the ability to overcome the innate immune response of flounder cells. To determine the innate immune response genes of virus-infected HINAE cells which are commonly modulated by the three novirhabdoviruses, we infected HINAE cells with novirhabdoviruses at multiplicity of infection (MOI) 1 and performed an RNA sequencing-based transcriptome analysis at 24 h post-infection. We discovered ~12,500 unigenes altered by novirhabdovirus infection and found that many of these were involved in multiple cellular pathways. After novirhabdovirus infection, 170 genes involved in the innate immune response were differentially expressed compared to uninfected cells. Among them, 9 genes changed expression by more than 2-fold and were commonly modulated by all three novirhabdoviruses. Interferon regulatory factor 8 (IRF8), C-X-C motif chemokine receptor 1 (CXCR1), Toll/interleukin-1 receptor domain-containing adapter protein (TIRAP), cholesterol 25-hydroxylase (CH25H), C-X-C motif chemokine ligand 11, duplicate 5 (CXCL11.5), and Toll-like receptor 2 (TLR2) were up-regulated, whereas C-C motif chemokine receptor 6a (CCR6a), interleukin-12a (IL12a), and Toll-like receptor 1 (TLR1) were down-regulated. These genes have been reported to be involved in antiviral responses and, thus, their modulation may be critical for the growth of novirhabdovirus in flounder cells. This is the first report to identify innate immune response genes in flounder that are commonly modulated by IHNV, VHSV, and HIRRV. These data will provide new insights into how novirhabdoviruses survive the innate immune response of flounder cells.
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Affiliation(s)
- Kwang Il Kim
- Pathology Research Division, National Institute of Fisheries Science, Busan, Korea
| | - Unn Hwa Lee
- Department of Biological Sciences, University of Ulsan, Ulsan, Korea
| | - Miyoung Cho
- Pathology Research Division, National Institute of Fisheries Science, Busan, Korea
| | - Sung-Hee Jung
- Pathology Research Division, National Institute of Fisheries Science, Busan, Korea
| | - Eun Young Min
- Pathology Research Division, National Institute of Fisheries Science, Busan, Korea
| | - Jeong Woo Park
- Department of Biological Sciences, University of Ulsan, Ulsan, Korea
- * E-mail:
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23
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Jones DR, Rutan BJ, Wargo AR. Impact of Vaccination and Pathogen Exposure Dosage on Shedding Kinetics of Infectious Hematopoietic Necrosis Virus (IHNV) in Rainbow Trout. JOURNAL OF AQUATIC ANIMAL HEALTH 2020; 32:95-108. [PMID: 32443164 PMCID: PMC7540492 DOI: 10.1002/aah.10108] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 04/03/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Vaccine efficacy in preventing clinical disease has been well characterized. However, vaccine impacts on transmission under diverse field conditions, such as variable pathogen exposure dosages, are not fully understood. We evaluated the impacts of vaccination on disease-induced host mortality and shedding of infectious hematopoietic necrosis virus (IHNV) in Rainbow Trout Oncorhynchus mykiss. Fish, in up to three different genetic lines, were exposed to different dosages of IHNV to simulate field variability. Mortality and viral shedding of each individual fish were quantified over the course of infection. As the exposure dosage increased, mortality, number of fish shedding virus, daily virus quantity shed, and total amount of virus shed also increased. Vaccination significantly reduced mortality but had a much smaller impact on shedding, such that vaccinated fish still shed significant amounts of virus, particularly at higher viral exposure dosages. These studies demonstrate that the consideration of pathogen exposure dosage and transmission are critical for robust inference of vaccine efficacy.
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Affiliation(s)
- Darbi R. Jones
- Virginia Institute of Marine ScienceWilliam & MaryPost Office Box 1346, 1370 Greate RoadGloucester PointVirginia23062USA
| | - Barbara J. Rutan
- Virginia Institute of Marine ScienceWilliam & MaryPost Office Box 1346, 1370 Greate RoadGloucester PointVirginia23062USA
| | - Andrew R. Wargo
- Virginia Institute of Marine ScienceWilliam & MaryPost Office Box 1346, 1370 Greate RoadGloucester PointVirginia23062USA
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24
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Tapia D, Barría A, Kuznar J, Yáñez JM. Comparison of mortality and viral load in rainbow trout (Oncorhynchus mykiss) infected with infectious pancreatic necrosis virus (IPNV) genogroups 1 and 5. JOURNAL OF FISH DISEASES 2020; 43:139-146. [PMID: 31724200 DOI: 10.1111/jfd.13113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 10/14/2019] [Accepted: 10/16/2019] [Indexed: 06/10/2023]
Abstract
Infectious pancreatic necrosis virus (IPNV) is the aetiological agent of a highly contagious disease that affects farmed salmonids. IPNV isolates have been phylogenetically classified into eight genogroups, of which two are present in Chile, genogroups 1 and 5. Here, we compare the mortality rate caused by isolates from both genogroups in rainbow trout (Oncorhynchus mykiss) fry to determine if there is an association between host susceptibility and phylogenetic characterization of IPNV. Fish were challenged by immersion with one of four isolates (two for each genogroup), and mortality curves were assessed after 30 days. Viral load was measured in all mortalities and in live fish sampled at 1, 7 and 20 days post-infection. Although mortality was low throughout the challenge, differences were found between fish infected with different isolates. Both isolates from genogroup 1 caused greater cumulative mortalities than either of the isolates from genogroup 5. When combined, the overall mortality rate of fish challenged with genogroup 1 isolates was significantly higher than those infected with genogroup 5. However, viral load was lower on trout infected with genogroup 1 isolates. These results suggest that rainbow trout are more susceptible to IPNV isolates from genogroup 1 than genogroup 5.
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Affiliation(s)
- David Tapia
- Doctorado en Acuicultura, Programa Cooperativo Universidad de Chile, Universidad Católica del Norte, Pontificia Universidad Católica de Valparaíso, Santiago, Chile
| | - Agustín Barría
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
| | - Juan Kuznar
- Centro de Investigación y Gestión de Recursos Naturales, Instituto de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - José M Yáñez
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
- Núcleo Milenio INVASAL, Concepción, Chile
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25
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A chimeric recombinant infectious hematopoietic necrosis virus induces protective immune responses against infectious hematopoietic necrosis and infectious pancreatic necrosis in rainbow trout. Mol Immunol 2019; 116:180-190. [PMID: 31704501 DOI: 10.1016/j.molimm.2019.10.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 10/23/2019] [Accepted: 10/23/2019] [Indexed: 12/18/2022]
Abstract
Infectious pancreatic necrosis virus (IPNV) and infectious hematopoietic necrosis virus (IHNV) are two common viral pathogens that cause severe economic losses in all salmonid species in culture, but especially in rainbow trout. Although vaccines against both diseases have been commercialized in some countries, no such vaccines are available for them in China. In this study, a recombinant virus was constructed using the IHNV U genogroup Blk94 virus as a backbone vector to express the antigenic gene, VP2, from IPNV via the reverse genetics system. The resulting recombinant virus (rBlk94-VP2) showed stable biological characteristics as confirmed by virus growth kinetic analyses, pathogenicity analyses, indirect immunofluorescence assays and western blotting. Rainbow trout were immunized with rBlk94-VP2 and then challenged with the IPNV ChRtm213 strain and the IHNV Sn1203 strain on day 45 post-vaccination. A significantly higher survival rate against IHNV was obtained in the rBlk94-VP2 group on day 45 post-vaccination (86%) compared with the PBS mock immunized group (2%). Additionally, IPNV loads decreased significantly in the rBlk94-VP2 immunized group in the liver (28.6-fold to 36.5-fold), anterior kidney (21.7-fold to 44.2-fold), and spleen (14.9-fold to 22.7-fold), as compared with the PBS mock control group. The mRNA transcripts for several innate and adaptive immune-related proteins (IFN-γ, IFN-1, Mx-1, CD4, CD8, IgM, and IgT) were also significantly upregulated after rBlk94-VP2 vaccination, and neutralizing antibodies against both IHNV and IPNV were induced on day 45 post-vaccination. Collectively, our results suggest that this recombinant virus could be developed as a vaccine vector to protect rainbow trout against two or more diseases, and our approach lays the foundations for developing live vaccines for rainbow trout.
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Abstract
How virulence evolves after a virus jumps to a new host species is central to disease emergence. Our current understanding of virulence evolution is based on insights drawn from two perspectives that have developed largely independently: long-standing evolutionary theory based on limited real data examples that often lack a genomic basis, and experimental studies of virulence-determining mutations using cell culture or animal models. A more comprehensive understanding of virulence mutations and their evolution can be achieved by bridging the gap between these two research pathways through the phylogenomic analysis of virus genome sequence data as a guide to experimental study.
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Affiliation(s)
- Jemma L Geoghegan
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences and Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.
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27
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Long A, Garver KA, Jones SRM. Synergistic osmoregulatory dysfunction during salmon lice (Lepeophtheirus salmonis) and infectious hematopoietic necrosis virus co-infection in sockeye salmon (Oncorhynchus nerka) smolts. JOURNAL OF FISH DISEASES 2019; 42:869-882. [PMID: 30977528 PMCID: PMC6850008 DOI: 10.1111/jfd.12989] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/14/2019] [Accepted: 02/15/2019] [Indexed: 05/03/2023]
Abstract
While co-infections are common in both wild and cultured fish, knowledge of the interactive effects of multiple pathogens on host physiology, gene expression and immune response is limited. To evaluate the impact of co-infection on host survival, physiology and gene expression, sockeye salmon Oncorhynchus nerka smolts were infected with the salmon louse Lepeophtheirus salmonis (V-/SL+), infectious hematopoietic necrosis virus (IHNV; V+/SL-), both (V+/SL+), or neither (V-/SL-). Survival in the V+/SL+ group was significantly lower than the V-/SL- and V-/SL+ groups (p = 0.024). Co-infected salmon had elevated osmoregulatory indicators and lowered haematocrit values as compared to the uninfected control. Expression of 12 genes associated with the host immune response was analysed in anterior kidney and skin. The only evidence of L. salmonis-induced modulation of the host antiviral response was down-regulation of mhc I although the possibility of modulation cannot be ruled out for mx-1 and rsad2. Co-infection did not influence the expression of genes associated with the host response to L. salmonis. Therefore, we conclude that the reduced survival in co-infected sockeye salmon resulted from the osmoregulatory consequences of the sea lice infections which were amplified due to infection with IHNV.
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Affiliation(s)
- Amy Long
- Fisheries and Ocean CanadaPacific Biological StationNanaimoBritish ColumbiaCanada
| | - Kyle A. Garver
- Fisheries and Ocean CanadaPacific Biological StationNanaimoBritish ColumbiaCanada
| | - Simon R. M. Jones
- Fisheries and Ocean CanadaPacific Biological StationNanaimoBritish ColumbiaCanada
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28
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Syahputra K, Kania PW, Al-Jubury A, Jafaar RM, Dirks RP, Buchmann K. Transcriptomic analysis of immunity in rainbow trout (Oncorhynchus mykiss) gills infected by Ichthyophthirius multifiliis. FISH & SHELLFISH IMMUNOLOGY 2019; 86:486-496. [PMID: 30513380 DOI: 10.1016/j.fsi.2018.11.075] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 11/22/2018] [Accepted: 11/30/2018] [Indexed: 06/09/2023]
Abstract
The parasite Ichthyophthirius multifiliis infecting skin, fins and gills of a wide range of freshwater fish species, including rainbow trout, is known to induce a protective immune response in the host. Although a number of studies have reported activation of several immune genes in infected fish host, the immune response picture is still considered incomplete. In order to address this issue, a comparative transcriptomic analysis was performed on infected versus uninfected rainbow trout gills and it showed that a total of 3352 (7.2%) out of 46,585 identified gene sequences were significantly regulated after parasite infection. Of differentially expressed gene sequences, 1796 genes were up-regulated and 1556 genes were down-regulated. These were classified into 61 Gene Ontology (GO) terms and mapped to 282 reference canonical pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Infection of I. multifiliis induced a clear differential expression of immune genes, related to both innate and adaptive immunity. A total of 268 (6.86%) regulated gene sequences were known to take part in 16 immune-related pathways. These involved pathways related to the innate immunity such as the Chemokine signaling pathway, Platelet activation, Toll-like receptor signaling pathway, NOD-like receptor signaling pathway, and Leukocyte transendothelial migration. Elevated transcription of genes encoding the TLR 8 gene and chemokines (CCL4, CCL19, CCL28, CXCL8, CXCL11, CXCL13, CXCL14) was recorded indicating their roles in recognition of I. multifiliis and subsequent induction of the inflammatory response, respectively. A number of upregulated genes in infected gills were associated with antigen processing/presentation and T and B cell receptor signaling (including B cell marker CD22 involved in B cell development). Overall the analysis supports the notion that I. multifiliis induces a massive and varied innate response upon which a range of adaptive immune responses are established which may contribute to the long lasting protection of immunized rainbow trout.
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Affiliation(s)
- Khairul Syahputra
- Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark.
| | - Per W Kania
- Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Azmi Al-Jubury
- Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Rzgar M Jafaar
- Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Ron P Dirks
- Future Genomics Technologies B.V., Leiden, the Netherlands
| | - Kurt Buchmann
- Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
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29
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Pannetier P, Morin B, Clérandeau C, Lacroix C, Cabon J, Cachot J, Danion M. Comparative biomarker responses in Japanese medaka (Oryzias latipes) exposed to benzo[a]pyrene and challenged with betanodavirus at three different life stages. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 652:964-976. [PMID: 30380501 DOI: 10.1016/j.scitotenv.2018.10.256] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 10/15/2018] [Accepted: 10/19/2018] [Indexed: 06/08/2023]
Abstract
It is now well documented that several contaminants can modulate the fish immune system, leading to disrupted host resistance against pathogens and increased incidence of disease. Since fish are usually co-exposed to chemicals and pathogens in the natural environment, analysis of the immunotoxic effects of pollutants is particularly relevant. The authorities in the European Union have recommended the development of toxicity assays on cell cultures and embryos, as an alternative to testing in vertebrates. This is why in our study, a fish immune challenge assay was developed for the early life stages of Japanese medaka to evaluate and compare the relevance of new biomarkers. Fish were exposed to benzo[a]pyrene (BaP), a model pollutant, for 8days at the embryonic stage, or for 48h at the larvae and juvenile stages, and fish were infected with betanodavirus by bath-challenge of 106TCID50/mL. Biometric changes and induction of malformations were observed after embryonic exposure. DNA damage and induction of EROD activity were recorded at the end of all chemical exposures. Viral infection increased the mortality rate significantly and disturbed the behavior of fish after light stimulation. While BaP exposure increased swimming speed, betanodavirus infection slowed swimming activity. In larvae co-exposed to BaP and the virus, the viral titer in the whole body was higher than in fish infected only with the virus. This study highlighted the sensitivity and usefulness of the immune challenge assay on the early life stages of Japanese medaka to evaluate the toxic effects of pollutants.
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Affiliation(s)
- Pauline Pannetier
- Bordeaux University, EPOC Laboratory, UMR 5805, F-33400 Talence, France
| | - Bénédicte Morin
- Bordeaux University, EPOC Laboratory, UMR 5805, F-33400 Talence, France
| | | | - Camille Lacroix
- Centre of Documentation, Research and Experimentation on Accidental Water Pollution (CEDRE), 715 Rue Alain Colas, 29200 Brest, France
| | - Joëlle Cabon
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan-Plouzané Laboratory, Fish Viral Pathology Unit, Technopôle Brest-Iroise, 29280 Plouzané, France
| | - Jérôme Cachot
- Bordeaux University, EPOC Laboratory, UMR 5805, F-33400 Talence, France
| | - Morgane Danion
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan-Plouzané Laboratory, Fish Viral Pathology Unit, Technopôle Brest-Iroise, 29280 Plouzané, France.
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Moreno P, Lopez-Jimena B, Randelli E, Scapigliati G, Buonocore F, Garcia-Rosado E, Borrego JJ, Alonso MC. Immuno-related gene transcription and antibody response in nodavirus (RGNNV and SJNNV)-infected European sea bass (Dicentrarchus labrax L.). FISH & SHELLFISH IMMUNOLOGY 2018; 78:270-278. [PMID: 29702239 DOI: 10.1016/j.fsi.2018.04.054] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/19/2018] [Accepted: 04/23/2018] [Indexed: 06/08/2023]
Abstract
The immune response of European sea bass to RGNNV and SJNNV infections has been evaluated by quantifying the transcription of some genes involved in the IFN I system, as well as in the inflammatory and adaptive immune mechanisms. The transcription of IFN-I, ISG-12, ISG-15 and MxA genes has been analyzed in brain and head kidney, showing that RGNNV genotype induces a more intense response of the IFN I system than SJNNV in both organs. In addition, the results obtained indicate the importance of the inflammatory response in nodavirus pathogenesis, with the transcription of IL-8 and TNF-α significantly higher in brain than in head kidney, being RGNNV the strongest inductor. An important difference between the immune response induced by both genotypes refers to the IgM titre in sera, which was higher in SJNNV-inoculated fish. The acquired response is also important locally, since TR-γ transcription is higher in brain than in head kidney (especially in the RGNNV-inoculated group). To our knowledge, this is the first study addressing the sea bass anti-SJNNV immune response.
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Affiliation(s)
- Patricia Moreno
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - Benjamin Lopez-Jimena
- Mast Group Ltd., Mast House, Derby Road, Bootle, Merseyside, L20 1EA, England, United Kingdom
| | - Elisa Randelli
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Giuseppe Scapigliati
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Francesco Buonocore
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Esther Garcia-Rosado
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - Juan J Borrego
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - M Carmen Alonso
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain.
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31
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Cao Y, Zhang Q, Xu L, Li S, Wang D, Zhao J, Liu H, Feng J, Lu T. Effects of different cytokines on immune responses of rainbow trout in a virus DNA vaccination model. Oncotarget 2017; 8:112222-112235. [PMID: 29348820 PMCID: PMC5762505 DOI: 10.18632/oncotarget.23095] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 11/17/2017] [Indexed: 11/26/2022] Open
Abstract
Seven rainbow trout cytokine genes (interleukin (IL)-2, IL-8, IL-15, IL-17, IL-1β, intracellular interferon (iIFN) 1a, and IFN-γ2) were evaluated for their adjuvant effects on a DNA vaccine, called pG, containing the glycoprotein gene of infectious hematopoietic necrosis virus (IHNV). Distinct DNA constructs in expression plasmid pcDNA3.1 encoding a cytokine gene were generated. Immunofluorescence assays in rainbow trout gonadal cells demonstrated successful protein expression from all these constructs. Subsequently, fish were immunized with pG alone or together with a cytokine expression plasmid. Results showed that each cytokine plasmids at an appropriate dose showed notable effects on immune gene expression. IL-17 and IFN-γ2 can enhance early specific IgM response. All cytokines, except IL-8, can benefit initial neutralizing antibody (NAb) titers. At 35 days post immunization (dpi), NAb titers of fish immunized with pG and IL-2, iIFN1a, or IFN-γ2 plasmids remained at high levels (1:160). NAb titers of fish immunized with pG alone decreased to 1:40. IL-8 or IL-1β can enhance antigen-specific proliferative T-cell responses at 14 dpi. At 28 dpi, coinjection of pG with IL-2, IL-8, IL-15, or IL-17 plasmids induced considerably stronger lymphocyte proliferation than that with injection of pG alone. All cytokine plasmids delivered with pG plasmid enhanced protection of trout against IHNV-mediated mortality. These results indicate that the type and dose of trout cytokine genes injected into fish affect quality of immune response to DNA vaccination.
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Affiliation(s)
- Yongsheng Cao
- Heilongjiang River Fishery Research Institute of Chinese Academy of Fishery Sciences, Harbin, China
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Qiya Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Liming Xu
- Heilongjiang River Fishery Research Institute of Chinese Academy of Fishery Sciences, Harbin, China
| | - Shaowu Li
- Heilongjiang River Fishery Research Institute of Chinese Academy of Fishery Sciences, Harbin, China
| | - Di Wang
- Heilongjiang River Fishery Research Institute of Chinese Academy of Fishery Sciences, Harbin, China
| | - Jingzhuang Zhao
- Heilongjiang River Fishery Research Institute of Chinese Academy of Fishery Sciences, Harbin, China
| | - Hongbai Liu
- Heilongjiang River Fishery Research Institute of Chinese Academy of Fishery Sciences, Harbin, China
| | - Jian Feng
- Benxi Agrimarine Company Limited, Benxi, China
| | - Tongyan Lu
- Heilongjiang River Fishery Research Institute of Chinese Academy of Fishery Sciences, Harbin, China
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32
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Abstract
Heterogeneity in host susceptibility is a key determinant of infectious disease dynamics but is rarely accounted for in assessment of disease control measures. Understanding how susceptibility is distributed in populations, and how control measures change this distribution, is integral to predicting the course of epidemics with and without interventions. Using multiple experimental and modeling approaches, we show that rainbow trout have relatively homogeneous susceptibility to infection with infectious hematopoietic necrosis virus and that vaccination increases heterogeneity in susceptibility in a nearly all-or-nothing fashion. In a simple transmission model with an R0 of 2, the highly heterogeneous vaccine protection would cause a 35 percentage-point reduction in outbreak size over an intervention inducing homogenous protection at the same mean level. More broadly, these findings provide validation of methodology that can help to reduce biases in predictions of vaccine impact in natural settings and provide insight into how vaccination shapes population susceptibility. Differences among individuals influence transmission and spread of infectious diseases as well as the effectiveness of control measures. Control measures, such as vaccines, may provide leaky protection, protecting all hosts to an identical degree, or all-or-nothing protection, protecting some hosts completely while leaving others completely unprotected. This distinction can have a dramatic influence on disease dynamics, yet this distribution of protection is frequently unaccounted for in epidemiological models and estimates of vaccine efficacy. Here, we apply new methodology to experimentally examine host heterogeneity in susceptibility and mode of vaccine action as distinct components influencing disease outcome. Through multiple experiments and new modeling approaches, we show that the distribution of vaccine effects can be robustly estimated. These results offer new experimental and inferential methodology that can improve predictions of vaccine effectiveness and have broad applicability to human, wildlife, and ecosystem health.
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Breyta R, Brito I, Ferguson P, Kurath G, Naish KA, Purcell MK, Wargo AR, LaDeau S. Transmission routes maintaining a viral pathogen of steelhead trout within a complex multi-host assemblage. Ecol Evol 2017; 7:8187-8200. [PMID: 29075442 PMCID: PMC5648648 DOI: 10.1002/ece3.3276] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/22/2017] [Accepted: 06/28/2017] [Indexed: 01/06/2023] Open
Abstract
This is the first comprehensive region wide, spatially explicit epidemiologic analysis of surveillance data of the aquatic viral pathogen infectious hematopoietic necrosis virus (IHNV) infecting native salmonid fish. The pathogen has been documented in the freshwater ecosystem of the Pacific Northwest of North America since the 1950s, and the current report describes the disease ecology of IHNV during 2000-2012. Prevalence of IHNV infection in monitored salmonid host cohorts ranged from 8% to 30%, with the highest levels observed in juvenile steelhead trout. The spatial distribution of all IHNV-infected cohorts was concentrated in two sub-regions of the study area, where historic burden of the viral disease has been high. During the study period, prevalence levels fluctuated with a temporal peak in 2002. Virologic and genetic surveillance data were analyzed for evidence of three separate but not mutually exclusive transmission routes hypothesized to be maintaining IHNV in the freshwater ecosystem. Transmission between year classes of juvenile fish at individual sites (route 1) was supported at varying levels of certainty in 10%-55% of candidate cases, transmission between neighboring juvenile cohorts (route 2) was supported in 31%-78% of candidate cases, and transmission from adult fish returning to the same site as an infected juvenile cohort was supported in 26%-74% of candidate cases. The results of this study indicate that multiple specific transmission routes are acting to maintain IHNV in juvenile fish, providing concrete evidence that can be used to improve resource management. Furthermore, these results demonstrate that more sophisticated analysis of available spatio-temporal and genetic data is likely to yield greater insight in future studies.
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Affiliation(s)
- Rachel Breyta
- Microbiology Oregon State University Corvallis OR USA.,Cary Institute for Ecosystems Studies Millbrook NY USA
| | - Ilana Brito
- Biomedical Engineering Cornell University Ithaca NY USA
| | - Paige Ferguson
- Biological Sciences University of Alabama Tuscaloosa AL USA
| | - Gael Kurath
- US Geological Survey, Western Fisheries Research Center Seattle WA USA
| | - Kerry A Naish
- School of Aquatic and Fisheries Sciences University of Washington Seattle WA USA
| | - Maureen K Purcell
- US Geological Survey, Western Fisheries Research Center Seattle WA USA
| | - Andrew R Wargo
- Department of Aquatic Health Sciences Virginia Institute of Marine Science Gloucester Point VA USA
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He L, Zhang A, Pei Y, Chu P, Li Y, Huang R, Liao L, Zhu Z, Wang Y. Differences in responses of grass carp to different types of grass carp reovirus (GCRV) and the mechanism of hemorrhage revealed by transcriptome sequencing. BMC Genomics 2017; 18:452. [PMID: 28595568 PMCID: PMC5465539 DOI: 10.1186/s12864-017-3824-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 05/28/2017] [Indexed: 11/28/2022] Open
Abstract
Background Grass carp is an important farmed fish in China that is affected by serious disease, especially hemorrhagic disease caused by grass carp reovirus (GCRV). The mechanism underlying the hemorrhagic symptoms in infected fish remains to be elucidated. Although GCRV can be divided into three distinct subtypes, differences in the pathogenesis and host immune responses to the different subtypes are still unclear. The aim of this study was to provide a comprehensive insight into the grass carp response to different GCRV subtypes and to elucidate the mechanism underlying the hemorrhagic symptoms. Results Following infection of grass carp, GCRV-I was associated with a long latent period and low mortality (42.5%), while GCRV-II was associated with a short latent period and high mortality (81.4%). The relative copy number of GCRV-I remained consistent or decreased slightly throughout the first 7 days post-infection, whereas a marked increase in GCRV-II high copy number was detected at 5 days post-infection. Transcriptome sequencing revealed 211 differentially expressed genes (DEGs) in Group I (66 up-regulated, 145 down-regulated) and 670 (386 up-regulated, 284 down-regulated) in Group II. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed significant enrichment in the terms or pathways involved in immune responses and correlating with blood or platelets. Most of the DEGs in Group I were also present in Group II, although the expression profiles differed, with most DEGs showing mild changes in Group I, while marked changes were observed in Group II, especially the interferon-related genes. Many of the genes involved in the complement pathway and coagulation cascades were significantly up-regulated at 7 days post-infection in Group II, suggesting activation of these pathways. Conclusion GCRV-I is associated with low virulence and a long latent period prior to the induction of a mild host immune response, whereas GCRV-II is associated with high virulence, a short latent period and stimulates a strong and extensive host immune response. The complement and coagulation pathways are significantly activated at 7 days post-infection, leading to the endothelial cell and blood cell damage that result in hemorrhagic symptoms. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3824-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Libo He
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Aidi Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Yongyan Pei
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengfei Chu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yongming Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Rong Huang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Lanjie Liao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Zuoyan Zhu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Yaping Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
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Christiansen DH, McBeath AJA, Aamelfot M, Matejusova I, Fourrier M, White P, Petersen PE, Falk K. First field evidence of the evolution from a non-virulent HPR0 to a virulent HPR-deleted infectious salmon anaemia virus. J Gen Virol 2017; 98:595-606. [PMID: 28475029 DOI: 10.1099/jgv.0.000741] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The putatively non-virulent subtype of infectious salmon anaemia virus (ISAV), ISAV-HPR0, is proposed to act as a progenitor and reservoir for all virulent ISAVs and thus represent a potential risk factor for the emergence of infectious salmon anaemia (ISA) disease. Here, we provide the first evidence of genetic and functional evolution from an ISAV-HPR0 variant (FO/07/12) to a low-virulent ISAV virus (FO/121/14) in a Faroese Atlantic salmon marine farm. The FO/121/14 virus infection was not associated with specific clinical signs of ISA and was confined to a single net-pen, while various ISAV-HPR0 subtypes were found circulating in most epidemiologically linked marine and freshwater farms. Sequence analysis of all eight segments revealed that the FO/121/14 virus was identical, apart from a substitution in the fusion (F) gene (Q266L) and a deletion in the haemagglutinin-esterase (HE) gene, to the FO/07/12 variant from a freshwater farm, which supplied smolts exclusively to the FO/121/14-positive net-pen. An immersion challenge with the FO/121/14 virus induced a systemic infection in Atlantic salmon associated with a low mortality and mild clinical signs confirming its low pathogenicity. Our results demonstrate that mutations in the F protein and deletions in the highly polymorphic region (HPR) of the HE protein represent a minimum requirement for ISAV to gain virulence and to switch cell tropism from a localized epithelial infection to a systemic endotheliotropic infection. This documents that ISAV-HPR0 represents a reservoir and risk factor for the emergence of ISA disease.
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Affiliation(s)
- Debes H Christiansen
- Faroese Food and Veterinary Authority, National Reference Laboratory for Fish Diseases, Tórshavn, Faroe Islands
| | | | | | | | | | - Patricia White
- Marine Scotland Science, Marine Laboratory, Aberdeen, Scotland
| | - Petra E Petersen
- Faroese Food and Veterinary Authority, National Reference Laboratory for Fish Diseases, Tórshavn, Faroe Islands
| | - Knut Falk
- Norwegian Veterinary Institute, Oslo, Norway
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36
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Ahmadivand S, Soltani M, Mardani K, Shokrpoor S, Hassanzadeh R, Ahmadpoor M, Rahmati-Holasoo H, Meshkini S. Infectious hematopoietic necrosis virus (IHNV) outbreak in farmed rainbow trout in Iran: Viral isolation, pathological findings, molecular confirmation, and genetic analysis. Virus Res 2016; 229:17-23. [PMID: 28012997 DOI: 10.1016/j.virusres.2016.12.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 12/16/2016] [Accepted: 12/16/2016] [Indexed: 11/28/2022]
Abstract
Infectious hematopoietic necrosis virus (IHNV) is the etiological agent of a contagious disease (IHN) mainly in salmonid fish. In the present study, we isolated and identified IHNV in trout fry from Iranian trout farms with unexplained high mortality in 2016. The affected fry showed cumulative mortality of 90% with the gross pathological signs including exophthalmia and hemorrhage of the eye, skin darkening, abdominal distension, ulceration of the snout, and the visceral pallor and yellowish fluid in the intestine. Histopathological examination revealed marked necrosis in the anterior kidney, liver and spleen with the intracytoplasmic inclusion bodies in the liver sections. Also, intranuclear inclusion body and marginated chromatin were observable in the hematopoietic cells of the kidney. The homogenates tissues of infected fry induced IHNV-positive cytopathic effects (CPE) in EPC cells and confirmed by RT-PCR reactions and sequencing. Phylogenetic analysis revealed the Iranian IHNV isolates belonged to the European (E) genogroup with 100% identity to some Italian isolates. This is the first report of IHNV infection in farmed trout fry in Iran describing the viral isolation, clinical symptoms, histopathological findings, molecular confirmation, and genetic analysis suggestion of the specific country of origin.
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Affiliation(s)
- Sohrab Ahmadivand
- Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, P.O. Box: 14155-6453, Tehran, Iran.
| | - Mehdi Soltani
- Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, P.O. Box: 14155-6453, Tehran, Iran; Centre of Excellence of Aquatic Animal Health, University of Tehran, Tehran, Iran.
| | - Karim Mardani
- Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
| | - Sara Shokrpoor
- Department of Pathology, Faculty of Veterinary Medicine, University of Tehran, P.O. Box: 14155-6453, Tehran, Iran
| | | | - Mehran Ahmadpoor
- Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, P.O. Box: 14155-6453, Tehran, Iran
| | - Hooman Rahmati-Holasoo
- Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, P.O. Box: 14155-6453, Tehran, Iran
| | - Saeid Meshkini
- Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
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37
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Wargo AR, Scott RJ, Kerr B, Kurath G. Replication and shedding kinetics of infectious hematopoietic necrosis virus in juvenile rainbow trout. Virus Res 2016; 227:200-211. [PMID: 27771253 DOI: 10.1016/j.virusres.2016.10.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 01/06/2023]
Abstract
Viral replication and shedding are key components of transmission and fitness, the kinetics of which are heavily dependent on virus, host, and environmental factors. To date, no studies have quantified the shedding kinetics of infectious hematopoietic necrosis virus (IHNV) in rainbow trout (Oncorhynchus mykiss), or how they are associated with replication, making it difficult to ascertain the transmission dynamics of this pathogen of high agricultural and conservation importance. Here, the replication and shedding kinetics of two M genogroup IHNV genotypes were examined in their naturally co-evolved rainbow trout host. Within host virus replication began rapidly, approaching maximum values by day 3 post-infection, after which viral load was maintained or gradually dropped through day 7. Host innate immune response measured as stimulation of Mx-1 gene expression generally followed within host viral loads. Shedding also began very quickly and peaked within 2days, defining a generally uniform early peak period of shedding from 1 to 4days after exposure to virus. This was followed by a post-peak period where shedding declined, such that the majority of fish were no longer shedding by day 12 post-infection. Despite similar kinetics, the average shedding rate over the course of infection was significantly lower in mixed compared to single genotype infections, suggesting a competition effect, however, this did not significantly impact the total amount of virus shed. The data also indicated that the duration of shedding, rather than peak amount of virus shed, was correlated with fish mortality. Generally, the majority of virus produced during infection appeared to be shed into the environment rather than maintained in the host, although there was more retention of within host virus during the post-peak period. Viral virulence was correlated with shedding, such that the more virulent of the two genotypes shed more total virus. This fundamental understanding of IHNV shedding kinetics and variation at the individual fish level could assist with management decisions about how to respond to disease outbreaks when they occur.
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Affiliation(s)
- Andrew R Wargo
- Virginia Institute of Marine Science, College of William and Mary, PO Box 1346, Gloucester Point, VA 23062, United States.
| | - Robert J Scott
- USGS Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115, United States
| | - Benjamin Kerr
- University of Washington, Department of Biology, Box 351800, Seattle, WA 98195, United States
| | - Gael Kurath
- USGS Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115, United States
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38
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Hernandez DG, Purcell MK, Friedman CS, Kurath G. Susceptibility of ocean- and stream-type Chinook salmon to isolates of the L, U, and M genogroups of infectious hematopoietic necrosis virus (IHNV). DISEASES OF AQUATIC ORGANISMS 2016; 121:15-28. [PMID: 27596856 DOI: 10.3354/dao03030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study examined the susceptibility of Chinook salmon Oncorhynchus tshawytscha to viral strains from the L, U, and M genogroups of infectious hematopoietic necrosis virus (IHNV) present in western North America. The goal of this investigation was to establish a baseline understanding of the susceptibility of ocean- and stream-type Chinook salmon to infection and mortality caused by exposure to commonly detected strains of L, U, and M IHNV. The L IHNV strain tested here was highly infectious and virulent in both Chinook salmon populations, following patterns previously reported for Chinook salmon. Furthermore, ocean- and stream-type Chinook salmon fry at 1 g can also become subclinically infected with U and M strains of IHNV without experiencing significant mortality. The stream-type life history phenotype was generally more susceptible to infection and suffered greater mortality than the ocean-type phenotype. Between the U and M genogroup strains tested, the U group strains were generally more infectious than the M group strains in both Chinook salmon types. Substantial viral clearance occurred by 30 d post exposure, but persistent viral infection was observed with L, U, and M strains in both host populations. While mortality decreased with increased host size in stream-type Chinook salmon, infection prevalence was not lower for all strains at a greater size. These results suggest that Chinook salmon may serve as reservoirs and/or vectors of U and M genogroup IHNV.
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Affiliation(s)
- Daniel G Hernandez
- University of Washington, School of Aquatic and Fishery Sciences, Box 355020, Seattle, WA 98195, USA
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39
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Wei X, Li XZ, Zheng X, Jia P, Wang J, Yang X, Yu L, Shi X, Tong G, Liu H. Toll-like receptors and interferon associated immune factors responses to spring viraemia of carp virus infection in common carp (Cyprinus carpio). FISH & SHELLFISH IMMUNOLOGY 2016; 55:568-576. [PMID: 27263115 DOI: 10.1016/j.fsi.2016.05.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 05/29/2016] [Accepted: 05/31/2016] [Indexed: 06/05/2023]
Abstract
Pattern recognition receptor (PRR) toll-like receptors (TLRs), antiviral agent interferon (IFN) and the effector IFN stimulated genes (ISGs) play a fundamental role in the innate immune response against viruses among all vertebrate classes. Common carp is a host for spring viraemia of carp virus (Rhabdovirus carpio, SVCV), which belong to Rhabdoviridae family. The present in-vivo experiment was conducted to investigate the expression of these innate immune factors in early phase as well as during recovery of SVCV infection by real-time quantitative reverse transcriptase polymerase chain reaction. A less lethal SVCV infection was generated in common carp (Cyprinus carpio) and was sampled at 3, 6, 12 h post infection (hpi), 1, 3, 5, 7 and 10 days post infection (dpi). At 3 hpi, the SVCV N gene was detected in all three fish and all three fish showed a relative fold increase of TLR2, TLR3 and TLR7, IFNa1, ISG15 and Vig1. Viral copies rapidly increased at 12 hpi then remained high until 5 dpi. When viral copy numbers were high, a higher expression of immune genes TLR2, TLR3, TLR7, IFNa1, IFNa2, IFNa1S, IFN regulatory factor 3 (IRF3), IRF7, interleukin 1β (IL1β), IL6, IL10, ADAR, ISG15, Mx1, PKR and Vig1 were observed. Viral copies were gradually reduced in 5 to 10 dpi fish, and also the immune response was considerably reduced but remained elevated. A high degree of correlation was observed between immune genes and viral copy number in each of the sampled fish at 12 hpi. The quick and prolonged elevated expression of the immune genes indicates their crucial role in survival of host against SVCV.
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Affiliation(s)
- Xinxian Wei
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China; Guangxi Academy of Fishery Science, Nanning 530021, China
| | - Xiao Zheng Li
- Guangxi Academy of Fishery Science, Nanning 530021, China
| | - Xiaocong Zheng
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China
| | - Peng Jia
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China
| | - Jinjin Wang
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China
| | - Xianle Yang
- College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China
| | - Li Yu
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China
| | - Xiujie Shi
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China
| | - Guixiang Tong
- Guangxi Academy of Fishery Science, Nanning 530021, China.
| | - Hong Liu
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen 518045, China.
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Susceptibility of goldsinny wrasse, Ctenolabrus rupestris L. (Labridae), to viral haemorrhagic septicaemia virus (VHSV) genotype III: Experimental challenge and pathology. Vet Microbiol 2016; 186:164-73. [PMID: 27016771 DOI: 10.1016/j.vetmic.2016.02.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 02/18/2016] [Accepted: 02/23/2016] [Indexed: 11/24/2022]
Abstract
Cleaner fish, such as wrasse, are being increasingly used to combat the sea lice infestation of Atlantic salmon (Salmo salar L.) in many European countries. To determine susceptibility of the goldsinny wrasse (Ctenolabrus rupestris L.) and pathogenesis of the viral haemorrhagic septicaemia virus (VHSV) genotype III isolate 12-654, previously associated with VHSV infection in the Shetland Islands in 2012, fish were experimentally challenged by intraperitoneal injection (IP), bath immersion and cohabitation routes. Cumulative proportion of moribund wrasse reached 17% following the virus immersion challenge while by the IP-route moribunds exceeded 50% within 14days post-challenge. Typical signs of VHS as reported in rainbow trout (Oncorhynchus mykiss), were not observed in moribund goldsinny wrasse. The most pronounced histopathological changes, consistent regardless of the route of infection, were observed within the heart and included atrium myofibril degeneration, focal infiltration and multifocal necrosis, with prominent swelling of the endocardium and occasional detachment. Pathological changes in the atrium were associated with presence of the viral antigen as confirmed by a positive immunohistochemical staining. Virus clearance and heart tissue recovery were noted although further experiments are required to confirm these observations. The results of a cohabitation experiment confirmed that goldsinny wrasse shed viable virus and therefore represent a risk of virus transmission to other VHSV susceptible species. Similarities between the pathology in goldsinny wrasse induced through the controlled experimental challenges and that of wrasse spp. from an infection occurrence in Shetland are discussed.
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Breyta R, McKenney D, Tesfaye T, Ono K, Kurath G. Increasing virulence, but not infectivity, associated with serially emergent virus strains of a fish rhabdovirus. Virus Evol 2016; 2:vev018. [PMID: 27774291 PMCID: PMC4989874 DOI: 10.1093/ve/vev018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Surveillance and genetic typing of field isolates of a fish rhabdovirus, infectious hematopoietic necrosis virus (IHNV), has identified four dominant viral genotypes that were involved in serial viral emergence and displacement events in steelhead trout (Oncorhynchus mykiss) in western North America. To investigate drivers of these landscape-scale events, IHNV isolates designated 007, 111, 110, and 139, representing the four relevant genotypes, were compared for virulence and infectivity in controlled laboratory challenge studies in five relevant steelhead trout populations. Viral virulence was assessed as mortality using lethal dose estimates (LD50), survival kinetics, and proportional hazards analysis. A pattern of increasing virulence for isolates 007, 111, and 110 was consistent in all five host populations tested, and correlated with serial emergence and displacements in the virus-endemic lower Columbia River source region during 1980-2013. The fourth isolate, 139, did not have higher virulence than the previous isolate 110. However, the mG139M genotype displayed a conditional displacement phenotype in that it displaced type mG110M in coastal Washington, but not in the lower Columbia River region, indicating that factors other than evolution of higher viral virulence were involved in some displacement events. Viral infectivity, measured as infectious dose (ID50), did not correlate consistently with virulence or with viral emergence, and showed a narrow range of variation relative to the variation observed in virulence. Comparison among the five steelhead trout populations confirmed variation in resistance to IHNV, but correlations with previous history of virus exposure or with sites of viral emergence varied between IHNV source and sink regions. Overall, this study indicated increasing viral virulence over time as a potential driver for emergence and displacement events in the endemic Lower Columbia River source region where these IHNV genotypes originated, but not in adjacent sink regions.
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Affiliation(s)
- Rachel Breyta
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and; School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St., Seattle, WA 98105, USA
| | - Doug McKenney
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and
| | - Tarin Tesfaye
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and
| | - Kotaro Ono
- School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St., Seattle, WA 98105, USA
| | - Gael Kurath
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115 and
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McKenney DG, Kurath G, Wargo AR. Characterization of infectious dose and lethal dose of two strains of infectious hematopoietic necrosis virus (IHNV). Virus Res 2016; 214:80-9. [PMID: 26752429 DOI: 10.1016/j.virusres.2015.12.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/22/2015] [Accepted: 12/22/2015] [Indexed: 11/24/2022]
Abstract
The ability to infect a host is a key trait of a virus, and differences in infectivity could put one virus at an evolutionary advantage over another. In this study we have quantified the infectivity of two strains of infectious hematopoietic necrosis virus (IHNV) that are known to differ in fitness and virulence. By exposing juvenile rainbow trout (Oncorhynchus mykiss) hosts to a wide range of virus doses, we were able to calculate the infectious dose in terms of ID50 values for the two genotypes. Lethal dose experiments were also conducted to confirm the virulence difference between the two virus genotypes, using a range of virus doses and holding fish either in isolation or in batch so as to calculate LD50 values. We found that infectivity is positively correlated with virulence, with the more virulent genotype having higher infectivity. Additionally, infectivity increases more steeply over a short range of doses compared to virulence, which has a shallower increase. We also examined the data using models of virion interaction and found no evidence to suggest that virions have either an antagonistic or a synergistic effect on each other, supporting the independent action hypothesis in the process of IHNV infection of rainbow trout.
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Affiliation(s)
- Douglas G McKenney
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115, United States.
| | - Gael Kurath
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115, United States.
| | - Andrew R Wargo
- Virginia Institute of Marine Science, 1375 Greate Rd., Gloucester Point, VA 23062, United States.
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43
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Kurath G, Winton JR, Dale OB, Purcell MK, Falk K, Busch RA. Atlantic salmon, Salmo salar L. are broadly susceptible to isolates representing the North American genogroups of infectious hematopoietic necrosis virus. JOURNAL OF FISH DISEASES 2016; 39:55-67. [PMID: 25381936 DOI: 10.1111/jfd.12323] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 09/19/2014] [Accepted: 09/22/2014] [Indexed: 06/04/2023]
Abstract
Beginning in 1992, three epidemic waves of infectious hematopoietic necrosis, often with high mortality, occurred in farmed Atlantic salmon Salmo salar L. on the west coast of North America. We compared the virulence of eleven strains of infectious hematopoietic necrosis virus (IHNV), representing the U, M and L genogroups, in experimental challenges of juvenile Atlantic salmon in freshwater. All strains caused mortality and there was wide variation within genogroups: cumulative mortality for five U-group strains ranged from 20 to 100%, four M-group strains ranged 30-63% and two L-group strains varied from 41 to 81%. Thus, unlike Pacific salmonids, there was no apparent correlation of virulence in a particular host species with virus genogroup. The mortality patterns indicated two different phenotypes in terms of kinetics of disease progression and final per cent mortality, with nine strains having moderate virulence and two strains (from the U and L genogroups) having high virulence. These phenotypes were investigated by histopathology and immunohistochemistry to describe the variation in the course of IHNV disease in Atlantic salmon. The results from this study demonstrate that IHNV may become a major threat to farmed Atlantic salmon in other regions of the world where the virus has been, or may be, introduced.
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Affiliation(s)
- G Kurath
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - J R Winton
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - O B Dale
- Norwegian Veterinary Institute, Oslo, Norway
| | - M K Purcell
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - K Falk
- Norwegian Veterinary Institute, Oslo, Norway
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Brieuc MSO, Purcell MK, Palmer AD, Naish KA. Genetic variation underlying resistance to infectious hematopoietic necrosis virus in a steelhead trout (Oncorhynchus mykiss) population. DISEASES OF AQUATIC ORGANISMS 2015; 117:77-83. [PMID: 26575157 DOI: 10.3354/dao02933] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding the mechanisms of host resistance to pathogens will allow insights into the response of wild populations to the emergence of new pathogens. Infectious hematopoietic necrosis virus (IHNV) is endemic to the Pacific Northwest and infectious to Pacific salmon and trout (Oncorhynchus spp.). Emergence of the M genogroup of IHNV in steelhead trout O. mykiss in the coastal streams of Washington State, between 2007 and 2011, was geographically heterogeneous. Differences in host resistance due to genetic change were hypothesized to be a factor influencing the IHNV emergence patterns. For example, juvenile steelhead trout losses at the Quinault National Fish Hatchery (QNFH) were much lower than those at a nearby facility that cultures a stock originally derived from the same source population. Using a classical quantitative genetic approach, we determined the potential for the QNFH steelhead trout population to respond to selection caused by the pathogen, by estimating the heritability for 2 traits indicative of IHNV resistance, mortality (h² = 0.377 (0.226 - 0.550)) and days to death (h² = 0.093 (0.018 - 0.203)). These results confirm that there is a genetic basis for resistance and that this population has the potential to adapt to IHNV. Additionally, genetic correlation between days to death and fish length suggests a correlated response in these traits to selection. Reduction of genetic variation, as well as the presence or absence of resistant alleles, could affect the ability of populations to adapt to the pathogen. Identification of the genetic basis for IHNV resistance could allow the assessment of the susceptibility of other steelhead populations.
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Affiliation(s)
- Marine S O Brieuc
- School of Aquatic and Fishery Sciences, University of Washington, Seattle 98195, WA, USA
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45
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Fourrier M, Lester K, Markussen T, Falk K, Secombes CJ, McBeath A, Collet B. Dual Mutation Events in the Haemagglutinin-Esterase and Fusion Protein from an Infectious Salmon Anaemia Virus HPR0 Genotype Promote Viral Fusion and Activation by an Ubiquitous Host Protease. PLoS One 2015; 10:e0142020. [PMID: 26517828 PMCID: PMC4627773 DOI: 10.1371/journal.pone.0142020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/15/2015] [Indexed: 11/24/2022] Open
Abstract
In Infectious salmon anaemia virus (ISAV), deletions in the highly polymorphic region (HPR) in the near membrane domain of the haemagglutinin-esterase (HE) stalk, influence viral fusion. It is suspected that selected mutations in the associated Fusion (F) protein may also be important in regulating fusion activity. To better understand the underlying mechanisms involved in ISAV fusion, several mutated F proteins were generated from the Scottish Nevis and Norwegian SK779/06 HPR0. Co-transfection with constructs encoding HE and F were performed, fusion activity assessed by content mixing assay and the degree of proteolytic cleavage by western blot. Substitutions in Nevis F demonstrated that K276 was the most likely cleavage site in the protein. Furthermore, amino acid substitutions at three sites and two insertions, all slightly upstream of K276, increased fusion activity. Co-expression with HE harbouring a full-length HPR produced high fusion activities when trypsin and low pH were applied. In comparison, under normal culture conditions, groups containing a mutated HE with an HPR deletion were able to generate moderate fusion levels, while those with a full length HPR HE could not induce fusion. This suggested that HPR length may influence how the HE primes the F protein and promotes fusion activation by an ubiquitous host protease and/or facilitate subsequent post-cleavage refolding steps. Variations in fusion activity through accumulated mutations on surface glycoproteins have also been reported in other orthomyxoviruses and paramyxoviruses. This may in part contribute to the different virulence and tissue tropism reported for HPR0 and HPR deleted ISAV genotypes.
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Affiliation(s)
- Mickael Fourrier
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
- * E-mail:
| | - Katherine Lester
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
| | | | - Knut Falk
- Epidemiology, Norwegian Veterinary Institute, Oslo, Norway
| | | | - Alastair McBeath
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
| | - Bertrand Collet
- Aquaculture and Fish Health, Marine Scotland Science, Aberdeen, United Kingdom
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Sun CB, Wang G, Chan SF. Effects of artificial infection of Litopenaeus vannamei by Micrococcus lysodeikticus and WSSV on the activity of immunity related enzymes. FISH & SHELLFISH IMMUNOLOGY 2015; 46:778-86. [PMID: 26117730 DOI: 10.1016/j.fsi.2015.06.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 06/22/2015] [Accepted: 06/22/2015] [Indexed: 05/20/2023]
Abstract
In this study, the activities of 5 immunity related enzymes namely acid phosphatase (ACP), alkaline phosphatase (AKP), phenoloxidase (PO), peroxidase (POD) and lysozyme phosphatase (LZM)) of Litopenaeus vannamei after they have been injected with different concentrations of Micrococcus lysodeikticus and the white spot syndrome virus (WSSV) were examined. The cumulative mortality at 0, 24, 48, 72, 96 h was obtained. Copy numbers of WSSV in L. vannamei after a single infection, secondary infection and concurrent infection were measured. Hemolymph samples of M. lysodeikticus and WSSV injected shrimp were collected at 0, 6, 12 24, 48, 72, 78, 84, 96 and 120 h. The results were: (i) The cumulative mortality of L. vannamei increased as the shrimp were infected with higher concentration of the bacteria; (ii) The most sensitive changes of ACP, AKP and LZM were in the 6.2 × 10(5), 6.2 × 10(6), 6.2 × 10(7) cfu/mL M. lysodeikticus group; (iii) ACP but LZM were more sensitive to M. lysodeikticus than WSSV, and AKP, PO and POD is more sensitive to WSSV; (iv) The copies of WSSV in the co-injected group were higher than WSSV-single infection and WSSV-bacteria-secondary infection group at 48 h. The amount of WSSV in L. vannamei of concurrent infection and WSSV-bacteria-secondary infection groups were higher than that of the WSSV-single infection group.
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Affiliation(s)
- Cheng-Bo Sun
- Fisheries College, Guangdong Ocean University, Zhanjiang 524025, China; Tropical Invertebrates Aquaculture Research Center of Guangdong Colleges and Universities, China; Cooperative and Innovation Center for Development and Utilization of Biological Resources in South China Sea, China
| | - Gang Wang
- Fisheries College, Guangdong Ocean University, Zhanjiang 524025, China
| | - Siuming F Chan
- Fisheries College, Guangdong Ocean University, Zhanjiang 524025, China; Tropical Invertebrates Aquaculture Research Center of Guangdong Colleges and Universities, China; Cooperative and Innovation Center for Development and Utilization of Biological Resources in South China Sea, China.
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47
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McBeath A, Aamelfot M, Christiansen DH, Matejusova I, Markussen T, Kaldhusdal M, Dale OB, Weli SC, Falk K. Immersion challenge with low and highly virulent infectious salmon anaemia virus reveals different pathogenesis in Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2015; 38:3-15. [PMID: 24820820 DOI: 10.1111/jfd.12253] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 06/03/2023]
Abstract
The salmonid orthomyxovirus infectious salmon anaemia virus (ISAV) causes disease of varying severity in farmed Atlantic salmon, Salmo salar L. Field observations suggest that host factors, the environment and differences between ISAV strains attribute to the large variation in disease progression. Variation in host mortality and dissemination of ISAV isolates with high and low virulence (based on a previously published injection challenge) were investigated using immersion challenge. Virus dissemination was determined using real-time PCR and immunohistochemistry in several organs, including blood. Surprisingly, the low virulent virus (LVI) replicated and produced nucleoprotein at earlier time points post-infection compared to the virus of high virulence (HVI). This was particularly noticeable in the gills as indicated by different viral load profiles. However, the HVI reached a higher maximum viral load in all tested organs and full blood. This was associated with a higher mortality of 100% as compared to 20% in the LVI group by day 23 post-infection. Immersion challenge represented a more natural infection method and suggested that specific entry routes into the fish may be of key importance between ISAV strains. The results suggest that a difference in virulence is important for variations in virus dissemination and pathogenesis (disease development).
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Affiliation(s)
- A McBeath
- Marine Scotland Science, Marine Laboratory, Aberdeen, UK
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48
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Breyta R, Jones A, Kurath G. Differential susceptibility in steelhead trout populations to an emergent MD strain of infectious hematopoietic necrosis virus. DISEASES OF AQUATIC ORGANISMS 2014; 112:17-28. [PMID: 25392039 DOI: 10.3354/dao02781] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A significant emergence of trout-adapted MD subgroup infectious hematopoietic necrosis virus (IHNV) began in the coastal region of Washington State, USA, in 2007. This emergence event lasted until 2011 and caused both asymptomatic adult fish infection and symptomatic epidemic disease and mortality in juvenile fish. Incidence of virus during this emergence demonstrated a heterogeneous distribution among rivers of the coastal region, leaving fish populations of some rivers apparently untouched while others suffered significant and recurrent infection and mortality (Breyta et. al. 2013; Dis Aquat Org 104:179-195). In this study, we examined the possible contribution of variations in susceptibility of fish populations, age-related resistance, and virus virulence to the observed landscape heterogeneity. We found that the most significant variable was host susceptibility: by controlled experimental challenge studies steelhead trout populations with no history of IHNV infection were 1 to 3 orders of magnitude more sensitive than a fish population with a long history of IHNV infection. In addition, 2 fish populations from the same river, which descended relatively recently from a common ancestral population, demonstrated 1 to 2 orders of magnitude difference in susceptibility. Fish age-related development of resistance was most evident in the more susceptible of 2 related fish populations. Finally, the strain of virus involved in the 2007 coastal Washington emergence had high virulence but was within the range of other known M group viruses tested. These results suggest that one major driver of landscape heterogeneity in the 2007 coastal Washington IHNV emergence was variation in fish population susceptibility and that this trait may have a heritable component.
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Affiliation(s)
- Rachel Breyta
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St., Seattle, WA 98115
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49
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McBeath AJA, Ho YM, Aamelfot M, Hall M, Christiansen DH, Markussen T, Falk K, Matejusova I. Low virulent infectious salmon anaemia virus (ISAV) replicates and initiates the immune response earlier than a highly virulent virus in Atlantic salmon gills. Vet Res 2014; 45:83. [PMID: 25143055 PMCID: PMC4144175 DOI: 10.1186/s13567-014-0083-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 07/24/2014] [Indexed: 01/12/2023] Open
Abstract
Observations from the field and experimental evidence suggest that different strains of infectious salmon anaemia virus (ISAV) can induce disease of varying severity in Atlantic salmon. Variation in host mortality and dissemination of ISAV isolates with high and low virulence was investigated using immersion challenge; from which mortality, pathological, immunohistochemical and preliminary molecular results have been previously published. Here, real-time RT-PCR analysis and statistical modelling have been used to further investigate variation in virus load and the response of four select immune genes. Expression of type I and II interferon (IFN), Mx and γIFN induced protein (γIP) to high and low pathogenic virus infection were examined in gill, heart and anterior kidney. In addition, a novel RNA species-specific assay targeting individual RNA types was used to investigate the separate viral processes of transcription and replication. Unexpectedly, the low virulent ISAV (LVI) replicated and transcribed more rapidly in the gills compared to the highly virulent virus (HVI). Subsequently LVI was able to disseminate to the internal organs more quickly and induced a more rapid systemic immune response in the host that may have offered some protection. Contrary to this, HVI initially progressed more slowly in the gills resulting in a slower generalised infection. However HVI ultimately reached a higher viral load and induced a greater mortality.
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Affiliation(s)
| | - Yee Mai Ho
- />Marine Scotland Science, Marine Laboratory, Aberdeen, Scotland UK
| | | | - Malcolm Hall
- />Marine Scotland Science, Marine Laboratory, Aberdeen, Scotland UK
| | | | | | - Knut Falk
- />Norwegian Veterinary Institute, Oslo, Norway
| | - Iveta Matejusova
- />Marine Scotland Science, Marine Laboratory, Aberdeen, Scotland UK
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50
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Palmer AD, Emmenegger EJ. Susceptibility of Koi and Yellow Perch to infectious hematopoietic necrosis virus by experimental exposure. JOURNAL OF AQUATIC ANIMAL HEALTH 2014; 26:78-83. [PMID: 24895860 DOI: 10.1080/08997659.2014.886634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Infectious hematopoietic necrosis virus (IHNV) is a novirhabdoviral pathogen that originated in western North America among anadromous Pacific salmonids. Severe disease epidemics in the late 1970s resulting from IHNV's invasion into farmed Rainbow Trout Oncorhynchus mykiss in North America, Asia, and Europe emphasized IHNV's ability to adapt to new hosts under varying rearing conditions. Yellow Perch Perca flavescens and Koi Carp Cyprinus carpio (hereafter, "Koi") are aquaculture-reared fish that are highly valued in sport fisheries and the ornamental fish trade, respectively, but it is unknown whether these fish species are vulnerable to IHNV infection. In this study, we exposed Yellow Perch, Koi, and steelhead (anadromous Rainbow Trout) to IHNV by intraperitoneal injection (10(6) PFU/fish) and by immersion (5.7×10(5) PFU/mL) for 7 h, and monitored fish for 28 d. The extended immersion exposure and high virus concentrations used in the challenges were to determine if the tested fish had any level of susceptibility. After experimental exposure, Yellow Perch and Koi experienced low mortality (<6%) compared with steelhead (>35%). Virus was found in dead fish of all species tested and in surviving Yellow Perch by plaque assay and quantitative reverse transcription polymerase chain reaction (qPCR), with a higher prevalence in Yellow Perch than Koi. Infectious virus was also detected in Yellow Perch out to 5 d after bath challenge. These findings indicate that Yellow Perch and Koi are highly resistant to IHNV disease under the conditions tested, but Yellow Perch are susceptible to infection and may serve as possible virus carriers.
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Affiliation(s)
- Alexander D Palmer
- a U.S. Geological Survey, Western Fisheries Research Center , 6505 Northeast 65th Street, Seattle , Washington 98115 , USA
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