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Lee HS, Bui VN, Dao DT, Bui NA, Le TD, Kieu MA, Nguyen QH, Tran LH, Roh JH, So KM, Hur TY, Oh SI. Pathogenicity of an African swine fever virus strain isolated in Vietnam and alternative diagnostic specimens for early detection of viral infection. Porcine Health Manag 2021; 7:36. [PMID: 33934707 PMCID: PMC8091783 DOI: 10.1186/s40813-021-00215-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 04/21/2021] [Indexed: 11/17/2022] Open
Abstract
Background African swine fever (ASF), caused by the ASF virus (ASFV), was first reported in Vietnam in 2019 and spread rapidly thereafter. Better insights into ASFV characteristics and early detection by surveillance could help control its spread. However, the pathogenicity and methods for early detection of ASFV isolates from Vietnam have not been established. Therefore, we investigated the pathogenicity of ASFV and explored alternative sampling methods for early detection. Results Ten pigs were intramuscularly inoculated with an ASFV strain from Vietnam (titer, 103.5 HAD50/mL), and their temperature, clinical signs, and virus excretion patterns were recorded. In addition, herd and environmental samples were collected daily. The pigs died 5–8 days-post-inoculation (dpi), and the incubation period was 3.7 ± 0.5 dpi. ASFV genome was first detected in the blood (2.2 ± 0.8) and then in rectal (3.1 ± 0.7), nasal (3.2 ± 0.4), and oral (3.6 ± 0.7 dpi) swab samples. ASFV was detected in oral fluid samples collected using a chewed rope from 3 dpi. The liver showed the highest viral loads, and ear tissue also exhibited high viral loads among 11 tissues obtained from dead pigs. Overall, ASFV from Vietnam was classified as peracute to acute form. The rope-based oral fluid collection method could be useful for early ASFV detection and allows successful ASF surveillance in large pig farms. Furthermore, ear tissue samples might be a simple alternative specimen for diagnosing ASF infection in dead pigs. Conclusions Our data provide valuable insights into the characteristics of a typical ASFV strain isolated in Vietnam and suggest an alternative, non-invasive specimen collection strategy for early detection.
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Affiliation(s)
- Hu Suk Lee
- International Livestock Research Institute (ILRI), Hanoi, Vietnam
| | - Vuong Nghia Bui
- Virology Department, National Institute of Veterinary Research, 86 Truong Chinh, Dong Da, Hanoi, Vietnam
| | - Duy Tung Dao
- Virology Department, National Institute of Veterinary Research, 86 Truong Chinh, Dong Da, Hanoi, Vietnam
| | - Ngoc Anh Bui
- Virology Department, National Institute of Veterinary Research, 86 Truong Chinh, Dong Da, Hanoi, Vietnam
| | - Thanh Duy Le
- Virology Department, National Institute of Veterinary Research, 86 Truong Chinh, Dong Da, Hanoi, Vietnam
| | - Minh Anh Kieu
- Virology Department, National Institute of Veterinary Research, 86 Truong Chinh, Dong Da, Hanoi, Vietnam
| | - Quang Huy Nguyen
- International Livestock Research Institute (ILRI), Hanoi, Vietnam.,Virology Department, National Institute of Veterinary Research, 86 Truong Chinh, Dong Da, Hanoi, Vietnam
| | - Long Hoang Tran
- Virology Department, National Institute of Veterinary Research, 86 Truong Chinh, Dong Da, Hanoi, Vietnam
| | - Jae-Hee Roh
- Division of Animal Disease & Health, National Institute of Animal Science, Rural Development Administration, 55365, Wanju, Republic of Korea
| | - Kyoung-Min So
- Division of Animal Disease & Health, National Institute of Animal Science, Rural Development Administration, 55365, Wanju, Republic of Korea
| | - Tai-Young Hur
- Division of Animal Disease & Health, National Institute of Animal Science, Rural Development Administration, 55365, Wanju, Republic of Korea
| | - Sang-Ik Oh
- Division of Animal Disease & Health, National Institute of Animal Science, Rural Development Administration, 55365, Wanju, Republic of Korea.
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Henao-Diaz A, Zhang M, Giménez-Lirola L, Ramirez E, Gauger P, Baum DH, Clavijo MJ, Rotolo M, Main RG, Zimmerman J. Adapting a porcine reproductive and respiratory syndrome virus (PRRSV) oral fluid antibody ELISA to routine surveillance. Prev Vet Med 2021; 188:105250. [PMID: 33429134 DOI: 10.1016/j.prevetmed.2020.105250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/20/2020] [Accepted: 12/21/2020] [Indexed: 10/22/2022]
Abstract
Distinct from tests used in diagnostics, tests used in surveillance must provide for detection while avoiding false alarms, i.e., acceptable diagnostic sensitivity but high diagnostic specificity. In the case of the reproductive and respiratory syndrome virus (PRRSV), RNA detection meets these requirements during the period of viremia, but antibody detection better meets these requirements in the post-viremic stage of the infection. Using the manufacturer's recommended cut-off (S/P ≥ 0.4), the diagnostic specificity of a PRRSV oral fluid antibody ELISA (IDEXX Laboratories, Inc., Westbrook, ME, USA) evaluated in this study was previously reported as ≥ 97 %. The aim of this study was to improve its use in surveillance by identifying a cut-off that would increase diagnostic specificity yet minimally impact its diagnostic sensitivity. Three sample sets were used to achieve this goal: oral fluids (n = 596) from pigs vaccinated with a modified live PRRSV vaccine under experimental conditions, field oral fluids (n = 1574) from 94 production sites of known negative status, and field oral fluids (n = 1380) from 211 sites of unknown PRRSV status. Based on the analysis of samples of known status (experimental samples and field samples from negative sites), a cut-off of S/P ≥ 1.0 resulted in a diagnostic specificity of 99.2 (95 % CI: 98.8, 99.7) and a diagnostic sensitivity of 96.5 (95 % CI: 85.2, 99.2). Among 211 sites of unknown status, 81 sites were classified as antibody positive using the manufacturer's cut-off; 20 of which were reclassified as negative using a cut-off of S/P ≥ 1.0. Further analysis showed that these 20 sites had a small proportion of samples (18.0 %) with S/P values just exceeding the manufacturer's cut-off (x̄ = 0.5). Whereas the remainder of positive sites (n = 61) had a high proportion of samples (76.3 %) with high S/P values (x̄ = 6.6). Thus, the manufacturer's cut-off (S/P ≥ 0.4) is appropriate for diagnostic applications, but a cut-off of S/P ≥ 1.0 provided the higher specificity required for surveillance. A previously unreported finding in this study was a statistically significant association between unexpected reactors and specific production sites and animal ages or stages. While beyond the scope of this study, these data suggested that certain animal husbandry or production practices may be associated with non-specific reactions.
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Affiliation(s)
- Alexandra Henao-Diaz
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - Min Zhang
- Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA, 50011, USA
| | - Luis Giménez-Lirola
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - Esteban Ramirez
- Grupo Porcícola Mexicano Kekén. Mérida, Yucatán, 97100, Mexico
| | - Phil Gauger
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - David H Baum
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - Maria J Clavijo
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA; PIC North America, 100 Bluegrass Commons Blvd. Ste. 2200, Hendersonville, TN, 37075, USA
| | - Marisa Rotolo
- PIC North America, 100 Bluegrass Commons Blvd. Ste. 2200, Hendersonville, TN, 37075, USA
| | - Rodger G Main
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA
| | - Jeffrey Zimmerman
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Iowa State University, Ames, IA, 50011, USA.
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Kittiwan N, Yamsakul P, Tadee P, Tadee P, Nuangmek A, Chuammitri P, Patchanee P. Immunological response to porcine reproductive and respiratory syndrome virus in young pigs obtained from a PRRSV-positive exposure status herd in a PRRSV endemic area. Vet Immunol Immunopathol 2019; 218:109935. [PMID: 31562984 DOI: 10.1016/j.vetimm.2019.109935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 08/15/2019] [Accepted: 08/30/2019] [Indexed: 10/26/2022]
Abstract
Porcine reproductive and respiratory syndrome (PRRS), caused by the PRRS virus (PRRSV), remains a major economic threat to swine production throughout the world. The aim of this study was to investigate the humoral and cell-mediated immune responses to PRRSV in 10 PRRSV vaccinated and 10 non-vaccinated young pigs obtained from a PRRSV-seropositive herd under field conditions. On day 35 days of post-vaccination (dpv), two PRRSV seropositive mixed-litter pigs were added to each group to co-mingle the animals. Serum and whole blood samples were collected from all pigs on the first day of vaccination, as well as on the 21, 35, 49, and 63 dpv. The PRRSV-specific humoral and cell-mediated immune response was determined by ELISA and flow cytometry analysis. The PRRSV ELISA sample to positive (S/P) ratio was found to be positive at the threshold level until the age of 84 days in both non-vaccinated and vaccinated groups, whereas the IFN-γ positive staining cytotoxic (CD8+) cells were rapidly expressed in the early periods of vaccination and co-mingling, but were not found to be specific to PRRSV. This result might have been due to an unspecific response to stress antigens. Further studies should be conducted to obtain more immune response data over long-term observation periods and to study the effect of PRRSV endemic strain vaccinations in endemically-infected herds.
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Affiliation(s)
- Nattinee Kittiwan
- Department of Food Animal Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand; Integrative Research Center for Veterinary Preventive Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand
| | - Panuwat Yamsakul
- Department of Food Animal Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand
| | - Pakpoom Tadee
- Department of Food Animal Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand; Integrative Research Center for Veterinary Preventive Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand
| | - Phacharaporn Tadee
- Faculty of Animal Science and Technology, Maejo University, Chiang Mai, 50290, Thailand
| | - Aniroot Nuangmek
- Department of Food Animal Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand; Integrative Research Center for Veterinary Preventive Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand
| | - Phongsakorn Chuammitri
- Department of Veterinary Biosciences and Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand; Excellent Center in Veterinary Biosciences (ECVB), Chiang Mai University, Chiang Mai, 50100, Thailand.
| | - Prapas Patchanee
- Department of Food Animal Clinics, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand; Integrative Research Center for Veterinary Preventive Medicine, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, 50100, Thailand.
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Toman M, Celer V, Kavanová L, Levá L, Frolichova J, Ondráčková P, Kudláčková H, Nechvátalová K, Salat J, Faldyna M. Dynamics and Differences in Systemic and Local Immune Responses After Vaccination With Inactivated and Live Commercial Vaccines and Subsequent Subclinical Infection With PRRS Virus. Front Immunol 2019; 10:1689. [PMID: 31447829 PMCID: PMC6691355 DOI: 10.3389/fimmu.2019.01689] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 07/04/2019] [Indexed: 12/12/2022] Open
Abstract
The goals of our study were to compare the immune response to different killed and modified live vaccines against PRRS virus and to monitor the antibody production and the cell mediated immunity both at the systemic and local level. In the experiment, we immunized four groups of piglets with two commercial inactivated (A1-Progressis, A2-Suivac) and two modified live vaccines (B3-Amervac, B4-Porcilis). Twenty-one days after the final vaccination, all piglets, including the control non-immunized group (C5), were i.n., infected with the Lelystad strain of PRRS virus. The serum antibody response (IgM and IgG) was the strongest in group A1 followed by two MLV (B3 and B4) groups. Locally, we demonstrated the highest level of IgG antibodies in bronchoalveolar lavages (BALF), and saliva in group A1, whereas low IgA antibody responses in BALF and feces were detected in all groups. We have found virus neutralization antibody at DPV 21 (days post vaccination) and higher levels in all groups including the control at DPI 21 (days post infection). Positive antigen specific cell-mediated response in lymphocyte transformation test (LTT) was observed in groups B3 and B4 at DPV 7 and in group B4 at DPV 21 and in all intervals after infection. The IFN-γ producing lymphocytes after antigen stimulation were found in CD4-CD8+ and CD4+CD8+ subsets of all immunized groups 7 days after infection. After infection, there were obvious differences in virus excretion. The virus was detected in all groups of piglets in serum, saliva, and occasionally in feces at DPI 3. Significantly lower virus load was found in groups A1 and B3 at DPI 21. Negative samples appeared at DPI 21 in B3 group in saliva. It can be concluded that antibodies after immunization and infection, and the virus after infection can be detected in all the compartments monitored. Immunization with inactivated vaccine A1-Progressis induces high levels of antibodies produced both systemically and locally. Immunization with MLV-vaccines (Amervac and Porcilis) produces sufficient antibody levels and also cell-mediated immunity. After infection virus secretion gradually decreases in group B3, indicating tendency to induce sterile immunity.
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Affiliation(s)
- Miroslav Toman
- Department of Immunology, Veterinary Research Institute, Brno, Czechia
| | - Vladimir Celer
- Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czechia
| | - Lenka Kavanová
- Department of Immunology, Veterinary Research Institute, Brno, Czechia
| | - Lenka Levá
- Department of Immunology, Veterinary Research Institute, Brno, Czechia
| | - Jitka Frolichova
- Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czechia
| | - Petra Ondráčková
- Department of Immunology, Veterinary Research Institute, Brno, Czechia
| | - Hana Kudláčková
- Department of Immunology, Veterinary Research Institute, Brno, Czechia
| | | | - Jiri Salat
- Department of Virology, Veterinary Research Institute, Brno, Czechia
| | - Martin Faldyna
- Department of Immunology, Veterinary Research Institute, Brno, Czechia
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