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Kroeger M, Temeeyasen G, Dilberger-Lawson S, Nelson E, Magtoto R, Gimenez-Lirola L, Piñeyro P. The porcine circovirus 3 humoral response: characterization of maternally derived antibodies and dynamic following experimental infection. Microbiol Spectr 2024:e0087024. [PMID: 38916319 DOI: 10.1128/spectrum.00870-24] [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: 04/07/2024] [Accepted: 05/17/2024] [Indexed: 06/26/2024] Open
Abstract
Since Porcine Circovirus 3 (PCV3) was first identified in 2016, our understanding of the humoral response is still relatively scarce. Current knowledge of the PCV3 humoral response is primarily based on field studies identifying the seroprevalence of PCV3 Cap-induced antibodies. Studies on the humoral response following experimental PCV3 infection have conflicting results where one study reports the development of the Cap IgG response 7 days postinfection with no concurrent Cap IgM response, while a second study shows a Cap IgM response at the same time point with no detection of Cap IgG. The dynamics of the PCV3 Cap and Rep IgG following maternal antibody transfer and experimental infection have not been well characterized. Additionally, the cross-reactivity of convalescent serum from PCV2 and PCV3 experimentally infected animals to serologic methods of the alternate PCV has limited evaluation. Here, we show that maternally derived antibodies were detectable in piglet serum 7-9 weeks postfarrowing for the Cap IgG and 5-weeks-post farrowing for the Rep IgG using Cap- and Rep-specific enzyme linked immunosorbent assays (ELISA) and immunofluorescent assays (IFA) methods. Following experimental inoculation, Cap IgG was detected at 2-weeks-post inoculation and Rep IgG detection was delayed until 4-weeks-post inoculation. Furthermore, convalescent serum from either PCV2 or PCV3 methods displayed no cross-reactivity by serological methods against the other PCV. The information gained in this study highlights the development of both the Cap- and Rep-specific antibodies following experimental infection and through the transfer of maternal antibodies. The increased understanding of the dynamics of maternal antibody transfer and development of the humoral response following infection gained in the present study may aid in the establishment of husbandry practices and potential application of prophylactics to control PCV3 clinical disease. IMPORTANCE Research on Porcine Circovirus 3 (PCV3) immunology is vital for understanding and controlling this virus. Previous studies primarily relied on field observations, but they have shown conflicting results about the immunological response against PCV3. This study helps fill those gaps by looking at how antibodies develop in pigs, especially those maternal-derived, and their impact in neonatal pigs preventing PCV3-associated disease in piglets. In addition, we look at the dynamics of antibodies in experimental infections mimicking infection in pigs in the grower-phase condition. Understanding this process can help to develop better strategies to prevent PCV3 infection. Also, this research found that PCV2 and PCV3 do not cross-react, which is crucial for serological test development and results interpretation. Overall, this work is essential for improving swine health and farming practices in the face of PCV3 infections.
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Affiliation(s)
- Molly Kroeger
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, USA
| | - Gun Temeeyasen
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, South Dakota, USA
| | - Steven Dilberger-Lawson
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, South Dakota, USA
| | - Eric Nelson
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, South Dakota, USA
| | - Ronaldo Magtoto
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, USA
| | - Luis Gimenez-Lirola
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, USA
| | - Pablo Piñeyro
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa, USA
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Wu X, Wang Q, Lu W, Wang Y, Han Z, Liang L, Gao S, Ma H, Luo X. The PCV3 Cap Virus-like Particle Vaccine with the Chimeric PCV2-Neutralizing Epitope Gene Is Effective in Mice. Vet Sci 2024; 11:264. [PMID: 38922011 PMCID: PMC11209062 DOI: 10.3390/vetsci11060264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 06/01/2024] [Accepted: 06/06/2024] [Indexed: 06/27/2024] Open
Abstract
Porcine circovirus type 3 (PCV3) infection can cause symptoms similar to those of porcine circovirus type 2 (PCV2) infection, and coinfections with both PCV2 and PCV3 are observed in the swine industry. Consequently, developing chimeric vaccines is essential to prevent and control porcine circovirus infections. In this study, we used both E. coli and mammalian expression systems to express PCV3 Cap (Cap3) and a chimeric gene containing the PCV2-neutralizing epitope within the PCV3 Cap (Cap3-Cap2E), which were assembled into virus-like particle (VLP) vaccines. We found that Cap3 lacking nuclear localization signal (NLS) could not form VLPs, while Cap3 with a His-tag successfully assembled into VLPs. Additionally, the chimeric of PCV2-neutralizing epitopes did not interfere with the assembly process of VLPs. Various immunization approaches revealed that pCap3-Cap2E VLP vaccines were capable of activating high PCV3 Cap-specific antibody levels and effectively neutralizing both PCV3 and PCV2. Furthermore, pCap3-Cap2E VLPs demonstrated a potent ability to activate cellular immunity, protecting against PCV3 infection and preventing lung damage in mice. In conclusion, this study successfully developed a PCV3 Cap VLP vaccine incorporating chimeric PCV2-neutralizing epitope genes, providing new perspectives for PCV3 vaccine development.
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Affiliation(s)
- Xingchen Wu
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Qikai Wang
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Wang Lu
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Ying Wang
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Zehao Han
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Libin Liang
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Shimin Gao
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Haili Ma
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
| | - Xiaomao Luo
- College of Veterinary Medicine, Shanxi Agricultural University, Jinzhong 030801, China; (X.W.)
- Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China
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Ham S, Suh J, Oh T, Kim C, Seo BJ, Chae C. Efficacy of a novel bivalent vaccine containing porcine circovirus type 2d and Mycoplasma hyopneumoniae against a dual PCV2d and Mycoplasma hyopneumoniae challenge. Front Vet Sci 2023; 10:1176091. [PMID: 37565086 PMCID: PMC10410152 DOI: 10.3389/fvets.2023.1176091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 07/10/2023] [Indexed: 08/12/2023] Open
Abstract
Background Information on efficacy of a novel bivalent vaccine containing porcine circovirus type 2d (PCV2d) and Mycoplasma hyopneumoniae. Objective To evaluate bivalent vaccine for efficacy under experimental conditions. Animals Clinically healthy 35 weaned piglets at 18 days of age were used. Methods A 2.0 mL dose of bivalent vaccine was administered intramuscularly to pigs at 21 days of age in accordance with the manufacturer's instructions. The pigs were challenged at 42 days of age either intranasally with PCV2d, or intratracheally with M. hyopneumoniae, or with both. Results Vaccinated-challenged pigs improved the growth performance compared to pigs that were unvaccinated and then, challenged. Vaccinated-challenged pigs elicited a significant amount of protective immunity for PCV2d-specific neutralizing antibodies and interferon-γ secreting cells (IFN-γ-SC) as well as for M. hyopneumoniae-specific IFN-γ-SC compared to unvaccinated/challenged pigs. Induction of systemic cellular and humoral immune responses from bivalent vaccination reduced the viral and mycoplasmal loads in the blood and larynx. Vaccination and challenge simultaneously reduced both lung and lymphoid lesion severity when compared to unvaccinated-challenged pigs. Discussion The results of this study demonstrated that the evaluated bivalent PCV2d and M. hyopneumoniae vaccine was efficacious in protecting pigs from the most predominant PCV2d genotype in the field today, as evaluated with a dual PCV2d and M. hyopneumoniae challenge under experimental conditions.
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Affiliation(s)
- Sehyeong Ham
- Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Jeongmin Suh
- Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Taehwan Oh
- Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | | | | | - Chanhee Chae
- Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
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Yu C, Cao M, Wei Y, Liu J, Zhang H, Liu C, Feng L, Huang L. Evaluation of cross-immunity among major porcine circovirus type 2 genotypes by infection with PCV2b and PCV2d circulating strains. Vet Microbiol 2023; 283:109796. [PMID: 37285792 DOI: 10.1016/j.vetmic.2023.109796] [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: 03/15/2023] [Revised: 05/28/2023] [Accepted: 05/30/2023] [Indexed: 06/09/2023]
Abstract
There are three main genotypes of porcine circovirus type 2 (PCV2), namely PCV2a, PCV2b and PCV2d, of which PCV2b and PCV2d are currently the most common. There are antigenic differences between these different genotypes. To explore the effect of PCV2 antigen differences on the immune protection provided by vaccines, a cross-immune protection test was carried out in pigs. Three genotype strains, PCV2a-CL, PCV2b-MDJ and PCV2d-LNHC, were inactivated and emulsified to prepare inactivated vaccines to immunize pigs, who were then challenged with the circulating strains PCV2b-BY and PCV2d-LNHC. Immunoperoxidase monolayer assays (IPMAs) and micro-neutralization assays were used to detect antibodies against the three different genotypes of PCV2. The results showed that the three genotype vaccines induced pigs to produce antibodies against the same and different genotypes of PCV2, but the levels of IPMA and neutralizing antibodies against the same genotype were higher than those against different genotypes. Quantitative Polymerase Chain Reaction (qPCR), virus titration and immunohistochemistry were used to detect PCV2 genomic DNA, live virus and antigen, respectively, in inguinal lymph nodes of experimental pigs. Following challenge with the PCV2b-BY strain, the viral DNA load in the inguinal lymph nodes of pigs immunized with the three genotype vaccines was reduced by more than 99 % compared to the unimmunized group. Following challenge with the PCV2d-LNHC strain, the viral DNA loads in the inguinal lymph nodes of pigs immunized with PCV2a, PCV2b and PCV2d genotype vaccines were reduced by 93.8 %, 99.8 % and 98.3 %, respectively, compared to unimmunized controls. In addition, neither live PCV2 virus nor antigen were detected in the inguinal lymph nodes of pigs immunized with any of the genotype vaccines (0/18), but both were detected in the lymph nodes of experimental pigs in the unimmunized control group (6/6). These findings suggest that, although the antigenic differences of the three genotype strains induce significant differences in antibody levels, they seem to have little effect on cross-protection between different genotypes.
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Affiliation(s)
- Chong Yu
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Mengxiang Cao
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Yanwu Wei
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Jianhang Liu
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Hao Zhang
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Changming Liu
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Li Feng
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China.
| | - Liping Huang
- Division of Swine Digestive System Infectious Diseases, State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China.
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Porcine Circovirus Type 2 Vaccines: Commercial Application and Research Advances. Viruses 2022; 14:v14092005. [PMID: 36146809 PMCID: PMC9504358 DOI: 10.3390/v14092005] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/06/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
Porcine circovirus type 2 (PCV2) infection can lead to porcine circovirus-associated disease (PCVAD), causing great economic losses to the global swine industry. Conventional vaccination programs are a major measure in the prevention and control of this disease. Currently, there are 5 commercially available PCV2 vaccines in the international market and 10 kinds commercially available PCV2 vaccines in the Chinese market that confer good efficacy against this virus by alleviating clinicopathological manifestations and enhancing growth performance in pigs. In addition, diverse experimental PCV2 vaccines with protective efficiency have been developed, including attenuated chimeric, nucleic acid, subunit, multivalent, and viral-vectored vaccines. These experimental vaccines have been shown to be relatively effective in improving the efficiency of pig production and simplifying prevention procedures. Adjuvants can be used to promote vaccines with higher protective immunity. Herein, we review the application of multiple commercial vaccines over the years and research advances in experimental vaccines, which provide the possibility for the development of superior vaccines to successfully prevent and control PCV2 infection in the future.
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Bandrick M, Balasch M, Heinz A, Taylor L, King V, Toepfer J, Foss D. A bivalent porcine circovirus type 2 (PCV2), PCV2a-PCV2b, vaccine offers biologically superior protection compared to monovalent PCV2 vaccines. Vet Res 2022; 53:12. [PMID: 35180885 PMCID: PMC8857852 DOI: 10.1186/s13567-022-01029-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 01/21/2022] [Indexed: 11/10/2022] Open
Abstract
Recent publications suggest PCV2 vaccine-induced protection is superior when the vaccine and challenge are closely matched. PCV2's evolutionary rate, propensity for recombination, and genotype shifting, all provide rationale for modernizing PCV2 vaccines. One mechanism to increase a vaccine's epitope breadth is by designing a bivalent vaccine. The objective of these studies was to evaluate efficacy of a monovalent (PCV1-2 chimera, cPCV2a or cPCV2b) and bivalent (cPCV2a-cPCV2b) vaccine in terms of homologous and heterologous efficacy. In Study A, pigs were vaccinated with cPCV2a or saline and challenged with PCV2a or PCV2b. In Study B, pigs were vaccinated with cPCV2a, cPCV2a-cPCV2b bivalent, or saline, and challenged with PCV2a. In Study C, pigs were vaccinated with cPCV2b, cPCV2a-cPCV2b bivalent, or saline, and challenged with PCV2b. In all studies vaccines and saline were administered intramuscularly to pigs at three to four weeks of age. Virulent PCV2b or PCV2a was administered to all animals approximately three weeks post-vaccination. Both mono and bivalent vaccinated groups demonstrated significantly lower viremia, percent of animals ever viremic, percent of animals with lymphoid depletion and/or histiocytic replacement, and percent of animals with PCV2 colonization of lymphoid tissues compared to saline controls. In Study A, a biologically relevant, though not significantly different, improvement in homologous versus heterologous protection was observed. In Studies B and C, biologically superior efficacy of the bivalent cPCV2a-cPCV2b vaccine compared to either monovalent vaccine was demonstrated. Taken together, cross-protection among mismatched PCV2 vaccine and challenge genotypes is not 100%; a bivalent PCV2 vaccine may provide the best opportunity to broaden coverage to circulating strains of PCV2.
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Affiliation(s)
- Meggan Bandrick
- Zoetis Inc, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA.
| | - Monica Balasch
- Zoetis Manufacturing and Research Spain S.L. , Ctra. Camprodon s/n, Finca La Riba, 17813, Vall de Bianya, Spain
| | - Andrea Heinz
- Zoetis Inc, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - Lucas Taylor
- Zoetis Inc, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - Vickie King
- Zoetis Inc, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - Jeri Toepfer
- Zoetis Inc, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
| | - Dennis Foss
- Zoetis Inc, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA
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Molecular Epidemic Characteristics and Genetic Evolution of Porcine Circovirus Type 2 (PCV2) in Swine Herds of Shanghai, China. Viruses 2022; 14:v14020289. [PMID: 35215883 PMCID: PMC8879946 DOI: 10.3390/v14020289] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/17/2022] [Accepted: 01/26/2022] [Indexed: 02/07/2023] Open
Abstract
Porcine Circovirus 2 (PCV2) is a crucial swine pathogen and considered a primary causative agent of porcine circovirus-associated diseases (PCVADs), posing a serious economic threat to the swine industry across globe. The world’s biggest agricultural conglomerates have teamed up to create giant commercial pig farms across Shanghai due to the proximity of this region to more affluent lean-pork markets. Since its discovery, PCV2 has displayed extraordinary genetic diversity, and its genome is swiftly evolving through a series of mutations and recombinations. However, limited information on epidemiology, molecular characteristics, vaccine cross-protection, and the co-infection rate of PCV2 with other lethal swine diseases can adversely impact the pig production in the region. To investigate the molecular epidemic characteristics and genetic evolution of PCV2, pigs with doubtful symptoms of PCVADs were sampled from various commercial pig farms with a history of PWMS and/or PDNS across Shanghai from 2014 to 2018. Our results revealed the coexistence of multiple PCV2 genotypes (PCV2b, PCV2e, and PCV2d) among Shanghai pig herds and dominance of PCV2d among them. We also found critical amino acid substitutions in epitope regions of important capsid proteins in PCV2 isolates involved in viral replication and host immune escape. Spotted mutations may favor the prevalence and survival of various PCV2 genotypes despite availability of commercial vaccines. This study also provides insight into the co-infection status of PCV2 with major lethal swine viral diseases such as PPV and PPRSV. Collectively, these investigations will contribute to understanding the molecular epidemiology and evolution of PCV2 across the region.
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Park Y, Min K, Kim NH, Kim JH, Park M, Kang H, Sohn EJ, Lee S. Porcine circovirus 2 capsid protein produced in N. benthamiana forms virus-like particles that elicit production of virus-neutralizing antibodies in guinea pigs. N Biotechnol 2021; 63:29-36. [PMID: 33667631 DOI: 10.1016/j.nbt.2021.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 02/03/2021] [Accepted: 02/25/2021] [Indexed: 10/22/2022]
Abstract
Porcine circovirus type 2 (PCV2) is a non-enveloped, icosahedral virus of the Circoviridae family, with a small, circular, single-stranded DNA genome. PCV2 infections cause substantial economic losses in the pig industry worldwide. Currently, commercially produced PCV2 vaccines are expensive, whereas plant-based expression systems can produce recombinant proteins at low cost for use as vaccines. In this study, recombinant PCV2 capsid protein (rCap) was transiently expressed in Nicotiana benthamiana and purified by metal affinity chromatography, with a yield of 102 mg from 1 kg plant leaves. Electron microscopy confirmed that purified rCap self-assembled into virus-like particles (VLPs) at neutral pH. It was shown to provoke a strong immune response in guinea pigs. The results indicate that plant systems can enable production of large amounts of proteins to serve as candidates for subunit vaccines.
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Affiliation(s)
- Youngmin Park
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea
| | - Kyungmin Min
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea
| | - Nam Hyung Kim
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea
| | - Ji-Hwan Kim
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea
| | - Minhee Park
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea
| | - Hyangju Kang
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea
| | - Eun-Ju Sohn
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea
| | - Sangmin Lee
- BioApplications Inc., Pohang Techno Park Complex, 394 Jigok-ro Nam-gu, Pohang, 37668, Republic of Korea.
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Evaluation of novel recombinant porcine circovirus type 2d (PCV2d) vaccine in pigs naturally infected with PCV2d. Vaccine 2020; 39:529-535. [PMID: 33342633 DOI: 10.1016/j.vaccine.2020.12.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 11/30/2020] [Accepted: 12/03/2020] [Indexed: 11/22/2022]
Abstract
INTRODUCTION The pathogenic porcine circovirus type 2 (PCV2) causes significant economic losses in pig production. Emergence of the PCV2d genotype has been linked with PCV2-associated disease (PCVAD) outbreaks. However, no study has been conducted efficacy of an experimental PCV2d-based subunit vaccine in pigs. Therefore, PCV2b- and PCV2d-based capsid (CP) proteins were generated using a baculovirus (Bac) expression system, and we evaluated the protective immune responses in a commercial pig farm where predominant PCV2d is circulating. METHODS Eighteen 3-week-old pigs with maternal antibodies were randomly divided into four groups, and were immunized with purified Bac-2dCP, mixed 1:1 ratio with purified Bac-2bCP and Bac-2dCP (Bac-mCP), a commercial PCV2a-based subunit vaccine (VAC) or phosphate-buffered saline (PBS) as controls. RESULTS The Bac-2dCP and Bac-mCP groups had significantly higher PCV2b- or PCV2d- specific IgG and neutralizing antibody without interference by maternal antibody compared to control group in pigs naturally infected with PCV2d. Interestingly, not only serum IL-4 level was significantly increased in the Bac-2dCP group, but also PCV2d viremia level was significantly reduced than the control group. CONCLUSIONS The recombinant Bac-2dCP subunit vaccine is a good candidate for the effective reduction against PCV2d infection.
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Porcine Circovirus 2 Genotypes, Immunity and Vaccines: Multiple Genotypes but One Single Serotype. Pathogens 2020; 9:pathogens9121049. [PMID: 33327478 PMCID: PMC7764931 DOI: 10.3390/pathogens9121049] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/08/2020] [Accepted: 12/12/2020] [Indexed: 02/06/2023] Open
Abstract
Identified for the first time in the 1990s, Porcine circovirus 2 (PCV-2) should not be considered an emerging virus anymore. Nevertheless, many aspects of its biology and epidemiology are still controversial. Particularly, its high evolutionary rate has caused the emergence of several variants and genotypes, alternating on the worldwide proscenium. The biological and practical implications of such heterogenicity are unfortunately largely unknown. The effectiveness of currently available vaccines against new genotypes that have emerged over time has been the topic of an intense debate and often inconclusive or contradictory results between experimental, field, and epidemiological studies have been gathered. The challenge in establishing an effective PCV-2 disease model, the peculiarities in experimental design and settings and the strains involved could justify the observed differences. The present work aims to summarize and critically review the available knowledge on PCV-2 genetic heterogeneity, immunity, and vaccine efficacy, organizing and harmonizing the available data from different sources, shedding light on this complex field and highlighting current knowledge gaps and future perspectives. So far, all vaccines in the market have shown great efficacy in reducing clinical signs associated to diseases caused by PCV-2, independently of the genotype present in the farm. Moreover, experimental data demonstrated the cross-protection of PCV-2a vaccines against the most widespread genotypes (PCV-2a, PCV-2b, and PCV-2d). Therefore, despite the significant number of genotypes described/proposed (PCV-2a to PCV-2i), it seems one single PCV-2 serotype would exist so far.
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Kang SJ, Kang H, You SH, Lee HJ, Lee N, Hyun BH, Cha SH. Genetic diversity and different cross-neutralization capability of porcine circovirus type 2 isolates recently circulating in South Korea. BMC Vet Res 2020; 16:334. [PMID: 32928247 PMCID: PMC7488706 DOI: 10.1186/s12917-020-02549-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 08/31/2020] [Indexed: 11/12/2022] Open
Abstract
Background Porcine circovirus type 2 (PCV2) is a small single-stranded DNA virus and a primary cause of PCV-associated diseases (PCVAD) that result insubstantial economic loss for swine farms. Between 2016 and 2018, PCV2 field viruses were isolated from PCVAD-affected swine farms in South Korea and investigated for genetic and antigenic heterogeneity. Results The genetic analysis of ORF2 showed that the genotype of the Korean PCV2 field isolates has been rapidly shifted from PCV2a or 2b to mutant PCV2b known as PCV2d with 82.6 to 100% amino acid sequence similarity. PCV2-specific monoclonal antibodies (mAbs) demonstrated variable antigen-binding activity to four representative Korean PCV2 field isolates [QIA215 (PCV2a), QIA418 (PCV2b), QIA169 (PCV2d), and QIA244 (PCV2d)] without genotype specificity, and one mAb showed neutralization activity to QIA215. In a cross-virus neutralization assay using anti-PCV2 sera of pigs and guinea pigs injected with a commercial vaccine and the Korean PCV2 field isolates, the anti-porcine sera of a commercial vaccine had high neutralization activity against QIA215 and QIA418 with statistically lower activity against PCV2d viruses. Anti-guinea pig sera of QIA215, QIA418, QIA169, and a commercial vaccine had high neutralization activity against all of the viruses with significantly lower activity against QIA244. Importantly, anti-guinea pig sera of QIA244 had high neutralization activity against all of the viruses. Conclusions This study confirmed genetic and antigenic diversity among recent PCV2 field isolates in Korean swine farms, and the strain-based difference in virus neutralization capability should be considered for more effective control by vaccination.
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Affiliation(s)
- Seok-Jin Kang
- Viral Disease Division, Animal and Plant Quarantine Agency, 177, Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea
| | - Hyeonjeong Kang
- Viral Disease Division, Animal and Plant Quarantine Agency, 177, Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea
| | - Su-Hwa You
- Viral Disease Division, Animal and Plant Quarantine Agency, 177, Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea
| | - Hye Jeong Lee
- Viral Disease Division, Animal and Plant Quarantine Agency, 177, Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea
| | - Nakhyung Lee
- KBNP, 415, Heungan-daero, Dongan-Gu, Anyang-si, Gyeonggi-do, 14059, Republic of Korea
| | - Bang-Hun Hyun
- Viral Disease Division, Animal and Plant Quarantine Agency, 177, Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea
| | - Sang-Ho Cha
- Viral Disease Division, Animal and Plant Quarantine Agency, 177, Hyeoksin 8-ro, Gimcheon-si, Gyeongsangbuk-do, 39660, Republic of Korea.
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12
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Targeted Alteration of Antibody-Based Immunodominance Enhances the Heterosubtypic Immunity of an Experimental PCV2 Vaccine. Vaccines (Basel) 2020; 8:vaccines8030506. [PMID: 32899842 PMCID: PMC7563983 DOI: 10.3390/vaccines8030506] [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: 07/14/2020] [Revised: 08/30/2020] [Accepted: 09/01/2020] [Indexed: 11/26/2022] Open
Abstract
Despite the availability of commercial vaccines which can effectively prevent clinical signs, porcine circovirus type 2 (PCV2) continues to remain an economically important swine virus, as strain drift, followed by displacement of new subtypes, occurs periodically. We had previously determined that the early antibody responses to the PCV2 capsid protein in infected pigs map to immunodominant but non-protective, linear B cell epitopes. In this study, two of the previously identified immunodominant epitopes were mutated in the backbone of a PCV2b infectious clone, to rationally restructure the immunogenic capsid protein. The rescued virus was used to immunize 3-week-old weanling piglets, followed by challenge with a virulent heterologous PCV2d strain. As expected, immunodominant antibody responses to the targeted epitopes were abrogated in vaccinated pigs, while a broadening of the virus neutralization responses was detected. Vaccinated pigs were completely protected against challenge viral replication, had reduced microscopic lesions in lymphoid organs and gained significantly more body weight when compared to unvaccinated pigs. Thus, the experimental PCV2 vaccine developed was highly effective against challenge, and, if adopted commercially, can potentially slow down or eliminate new strain creation.
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13
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Porcine circovirus type 2 (PCV2) genotyping in Austrian pigs in the years 2002 to 2017. BMC Vet Res 2020; 16:198. [PMID: 32539835 PMCID: PMC7294622 DOI: 10.1186/s12917-020-02413-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 06/04/2020] [Indexed: 12/19/2022] Open
Abstract
Background Eight different PCV2 genotypes with varying prevalence and clinical impact have been described so far. PCV2 infection is still widespread among the vaccinated population and several experimental studies have clearly demonstrated that there is no induction of a 100% cross-protective immunity between the PCV2 genotypes. Hence, PCV2a-based vaccines may be ineffective. In this longitudinal study, the PCV2 genotype and haplotype evolution in Austria in the years 2002 to 2017 was investigated by phylogenetic analysis of 462 bp-long sequences of the capsid protein gene (ORF2). The obtained findings may be of practical relevance for the future development of vaccination strategies. Results One hundred thirty four of a total of 161 formalin-fixed and paraffin wax-embedded samples could be sequenced successfully. There was no significant influence of storage time on sequencing success or quality. PCV2a (8.2%), PCV2b (77.6%), PCV2d (13.4%), and PCV2g (0.8%) were found. PCV2d was first detected as early as in 2004. PCV2g was described once in 2009. Both global PCV2 genotype shifts were observed. PCV2a occurred with a low prevalence during the first study years only in samples from non-vaccinated swine herds and was gradually replaced by PCV2b until 2011. PCV2b was the most prevalent genotype over the whole study period and was detected in samples from vaccinated and non-vaccinated herds. During the last two study years, the prevalence of PCV2d increased, although at this point almost all herds were vaccinated. The haplotype diversity was high, but the nucleotide diversity was low. Especially for genotype PCV2b, an increase in haplotype diversity could be described during the first study years. Conclusion Extensive PCV2a-derived vaccination resulted in a reduction of prevalence and in a stabilization of genotype PCV2a, whereas genotypes PCV2b and PCV2d evolved as a consequence of natural and vaccination-induced selection. An ongoing virus circulation may be the result of reduced vaccine-induced protection.
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14
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Cui X, Wang X, Gao Q, Liu X, Kai Y, Chen C, Gao S. Colonisation of mice and pigs by a chimeric porcine circovirus 1-2 prototype vaccine strain and a PCV2 isolate originating in China and their induction of cytokines. J Virol Methods 2020; 283:113905. [PMID: 32502500 DOI: 10.1016/j.jviromet.2020.113905] [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: 01/27/2019] [Revised: 05/20/2020] [Accepted: 05/21/2020] [Indexed: 10/24/2022]
Abstract
A chimeric porcine circovirus (PCV) 1-2b vaccine strain and its parental wild-type PCV2b strain from China (PCV2-J) were used separately to vaccinate BALB/c mice and tissue and serum samples were collected from the mice to investigate whether the replication properties of the viruses differed. The spleen lymphocytes from the infected mice were cultured in vitro; the amounts of interferon-γ-secreting cells (IFN-γ-SCs) and levels of interleukin (IL) 2, IL-4 and IL-10 in the culture fluids were monitored. The results showed that PCV1-2b induced higher levels of antibody production in the infected mice than the PCV2b-J isolate. Viremia declined gradually in both infection groups and the DNA copy numbers were nearly equal in both groups of mouse tissues tested. The IFN-γ-SC levels were clearly up-regulated in both the PCV1-2b- and PCV2b-J-infected mice. In both mouse groups, IL-2 was up-regulated, and IL-10 was detected at low levels, while IL-4 was always below the limit of detection. Similar experiments were performed in pigs and the results showed that when infected with either PCV1-2b or PCV2b-J the pigs experienced high-level antibody responses, with no significant differences between the infection groups. In the pig model, the development of IFN-γ-SCs in response to PCV1-2b and PCV2b-J infections was detected. However, the PCV1-2b strain tended to elicit more IFN-γ-SCs in the peripheral blood mononuclear cell population of the infected pigs from 21 to 28 days post infection than the PCV2b-J isolate did. The concentrations of IL-2 were transiently different between the PCV1-2b and PCV2b-J infected pigs, while those of IL-10 and IL-2 were similar in both groups, but were lower than those elicited in mice. These results indicated that BALB/c mouse could be used as an alternate model for evaluating the efficacy of attenuated PCV1-2b vaccines.
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Affiliation(s)
- Xiang Cui
- Key Laboratory of Avian Bioproduct Development, Ministry of Agriculture and Rural Affairs. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, PR China; College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Xiaobo Wang
- Key Laboratory of Avian Bioproduct Development, Ministry of Agriculture and Rural Affairs. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, PR China; College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Qingqing Gao
- Key Laboratory of Avian Bioproduct Development, Ministry of Agriculture and Rural Affairs. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, PR China; College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Xiufan Liu
- Key Laboratory of Avian Bioproduct Development, Ministry of Agriculture and Rural Affairs. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, PR China; College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China
| | - Yan Kai
- Jiangsu Provincial Center for Animal Disease Control and Prevention, Nanjing, Jiangsu 210036, China
| | - Changhai Chen
- Jiangsu Provincial Center for Animal Disease Control and Prevention, Nanjing, Jiangsu 210036, China
| | - Song Gao
- Key Laboratory of Avian Bioproduct Development, Ministry of Agriculture and Rural Affairs. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses. Yangzhou University, Yangzhou, Jiangsu, 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, PR China; College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
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15
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Bandrick M, Gutiérrez AH, Desai P, Rincon G, Martin WD, Terry FE, De Groot AS, Foss DL. T cell epitope content comparison (EpiCC) analysis demonstrates a bivalent PCV2 vaccine has greater T cell epitope overlap with field strains than monovalent PCV2 vaccines. Vet Immunol Immunopathol 2020; 223:110034. [PMID: 32278900 DOI: 10.1016/j.vetimm.2020.110034] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 02/17/2020] [Accepted: 03/03/2020] [Indexed: 01/14/2023]
Abstract
Porcine circovirus type 2 (PCV2) has one of the highest evolutionary rates among DNA viruses. Traditionally, PCV2 vaccines have been based on the 2a genotype as this was the first genotype discovered. Today, eight genotypes of PCV2 viruses have been identified, and, taken together with the rapid evolutionary rate, propensity to recombine, and high rate of vaccination, further variation in PCV2 is expected. For these reasons, there is a growing genetic gap between available vaccines and field strains. When selecting vaccines, it is important to consider vaccines that contain T cell epitopes that are well-matched to the circulating strains. To quantify the relatedness between PCV2 vaccines and field strains, we predicted and compared their T cell epitope content and calculated Epitope Content Comparison (EpiCC) scores using established in silico tools. T cell epitopes predicted to bind common class I and class II swine leukocyte antigen (SLA) alleles were identified from two major structural proteins, the capsid (encoded by ORF2) and the replicase (encoded by ORF1). The T cell epitope content of three commercial PCV2a-based vaccines (a baculovirus expressed PCV2a ORF2 [VacAlt], a PCV1-PCV2a chimeric virus vaccine [VacA] and a combination cPCV2a-cPCV2b chimeric virus vaccine [VacAB]) and an experimental PCV2b ORF2-based chimeric virus vaccine [VacB] (Table 1), were compared to that of 161 PCV2 field strains (representing genotypes a-f). The T cell epitope content and conservation between vaccine and field strains varied. While all vaccine strains provided broad coverage of the field strains including heterologous genotypes, none of the vaccines covered all the putative T cell epitopes identified in the field strains. PCV2a-based vaccine strains generally scored higher in terms of conserved epitope content against PCV2a field isolates but were not identical. The PCV2b-based vaccine strain had higher scores against PCV2b and PCV2d field strains. The combination PCV2a-PCV2b vaccine (VacAB) had, on average, the highest EpiCC score. PCV2 continues to evolve and EpiCC analysis provides a new tool to assess the possible impact of virus genetic divergence on T cell epitope coverage of vaccine strains. Given that multiple genotypes are currently found and may co-exist on farms, this analysis suggests that a combination of PCV2a and PCV2b vaccine strains may be required to provide optimal coverage of current and future field isolates.
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Affiliation(s)
| | | | | | | | | | | | - Anne S De Groot
- EpiVax, Inc., Providence, RI, United States; Center for Vaccines and Immunology, University of Georgia, Athens, GA, United States
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16
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Opriessnig T, Karuppannan AK, Halbur PG, Calvert JG, Nitzel GP, Matzinger SR, Meng XJ. Porcine circovirus type 2a or 2b based experimental vaccines provide protection against PCV2d/porcine parvovirus 2 co-challenge. Vaccine 2020; 38:1975-1981. [PMID: 31974016 DOI: 10.1016/j.vaccine.2020.01.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/31/2019] [Accepted: 01/04/2020] [Indexed: 10/25/2022]
Abstract
With the discovery of Porcine circovirus type 2d (PCV2d) in the USA in 2012 and subsequent genotype shift from the previously predominant PCV2b to PCV2d in the face of widespread PCV2a vaccination, concerns over PCV2 vaccine efficacy were raised. The objective of this study was to evaluate the efficacy of two similarly produced PCV2 vaccines, one containing the PCV2a capsid and the other one containing the PCV2b capsid, in the conventional pig model against PCV2d/porcine parvovirus 2 (PPV2) co-challenge. A co-challenge was added since there is evidence that PPV2 may exacerbate PCV2 infection and since PCV2 only rarely causes disease in experimentally infected pigs, hence vaccine efficacy can be difficult to assess. In brief, sixty 3-week-old-pigs from a PCV2 seropositive farm without evidence of active virus replication (no PCV2 viremia, low antibody titers with no evidence of increase after two consecutive bleedings) were blocked by PCV2 antibody titer and then randomly divided into three groups with 20 pigs each, a non-vaccinated group (challenge control), a PCV2a vaccinated group (VAC2a) and a PCV2b vaccinated group (VAC2b). Vaccinations were done at 4 and again at 6 weeks of age. At 8 weeks of age, all pigs were challenged with a PCV2d strain via intranasal and intramuscular routes of inoculation followed by intramuscular administration of PPV2 one day later. PCV2 vaccination, regardless of PCV2 genotype, resulted in significantly higher humoral and cellular immunity compared to non-vaccinated challenge control pigs as evidenced by increased numbers of interferon (IFN) γ secreting cells after PCV2d stimulation of peripheral blood mononuclear cells collected prior to challenge. Furthermore, PCV2a and PCV2b vaccinations both reduced PCV2d viremia and PCV2-associated pathological lesions. Under the study conditions, the PCV2a and PCV2b vaccine preparations each induced immune responses and clinical protection against a heterologous PCV2d/PPV2 co-challenge.
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Affiliation(s)
- Tanja Opriessnig
- The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom; Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
| | - Anbu K Karuppannan
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Patrick G Halbur
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Jay G Calvert
- Veterinary Medicine Research & Development, Zoetis Inc., Kalamazoo, MI, USA
| | - Gregory P Nitzel
- Veterinary Medicine Research & Development, Zoetis Inc., Kalamazoo, MI, USA
| | - Shannon R Matzinger
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Xiang-Jin Meng
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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17
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Huan C, Fan M, Cheng Q, Wang X, Gao Q, Wang W, Gao S, Liu X. Evaluation of the Efficacy and Cross-Protective Immunity of Live-Attenuated Chimeric PCV1-2b Vaccine Against PCV2b and PCV2d Subtype Challenge in Pigs. Front Microbiol 2018; 9:455. [PMID: 29599761 PMCID: PMC5862802 DOI: 10.3389/fmicb.2018.00455] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/27/2018] [Indexed: 01/22/2023] Open
Abstract
Porcine circovirus type 2 (PCV2) commercial vaccines are either inactivated PCV2 isolates or subunit vaccine based on the Cap protein of PCV2. Currently, no live-attenuated vaccines are yet available. Although the predominant circulating subtype worldwide is PCV2b, the emerging PCV2d subtype is also increasingly associated with PCV disease. In this study, piglets were inoculated with a live-attenuated chimeric PCV1-2b vaccine before challenged with PCV2b and PCV2d isolates. Thirty-two piglets were randomly divided into seven groups: negative (sham-vaccinated, sham-challenged), VAC+PCV2b (PCV1-2b vaccinated, PCV2b-challenged), VAC+PCV2d (PCV1-2b vaccinated, PCV2d-challenged), CHAL+PCV2b (sham-vaccinated, PCV2b-challenged), CHAL+PCV2d (sham-vaccinated, PCV2d-challenged), CV+PCV2b (commercial-vaccinated, PCV2b-challenged), and CV+PCV2d (commercial-vaccinated, PCV2d-challenged). The results showed that vaccinated challenged groups demonstrated high levels of anti-PCV2 antibody and reduced PCV2b and PCV2d loads both in serum and nasal swabs compared with the challenge-only groups. PCV2 DNA was detected in the superficial inguinal lymph nodes of only one pig in each of the VAC+PCV2b and VAC+PCV2d groups (group mean values, 101.81 and 101.77 genomic copies/g, respectively), which was significantly lower than those in CHAL+PCV2b and CHAL+PCV2d animals (group mean values, 1011.65 and 1010.60 genomic copies/g, respectively; P < 0.01). In addition, PCV2 DNA in each of the VAC+PCV2b and VAC+PCV2d groups was significantly lower than those in CV+PCV2b and CV+PCV2d animals (group mean values, 108.47 and 108.34 genomic copies/g, respectively; P < 0.01), indicating that the live-attenuated PCV1-2b vaccine was more effective than commercial vaccine. The live-attenuated PCV1-2b vaccine was effective in reducing PCV2b/PCV2d viremia, shedding, and tissue viral loads in vaccinated challenged pigs compared with challenge-only piglets, indicating that the PCV1-2b prototype vaccine is a good candidate for a live-attenuated vaccine against both PCV2b and PCV2d subtypes. And we first revealed that the live-attenuated PCV1-2b vaccine could protect piglets from challenge with either PCV2b or PCV2d equivalently.
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Affiliation(s)
- Changchao Huan
- Key Laboratory of Avian Bioproducts Development, Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Institutes of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Mingyu Fan
- Key Laboratory of Avian Bioproducts Development, Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Institutes of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Qingru Cheng
- Key Laboratory of Avian Bioproducts Development, Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Institutes of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Xiaobo Wang
- Key Laboratory of Avian Bioproducts Development, Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Institutes of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Qingqing Gao
- Key Laboratory of Avian Bioproducts Development, Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Institutes of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Wanbin Wang
- Postgraduates Training Station of Jiangsu Province, Taizhou, China
| | - Song Gao
- Key Laboratory of Avian Bioproducts Development, Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Institutes of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Postgraduates Training Station of Jiangsu Province, Taizhou, China
| | - Xiufan Liu
- Key Laboratory of Avian Bioproducts Development, Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, China.,Institutes of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
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18
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Tian D, Sooryanarain H, Matzinger SR, Gauger PC, Karuppannan AK, Elankumaran S, Opriessnig T, Meng XJ. Protective efficacy of a virus-vectored multi-component vaccine against porcine reproductive and respiratory syndrome virus, porcine circovirus type 2 and swine influenza virus. J Gen Virol 2017; 98:3026-3036. [DOI: 10.1099/jgv.0.000964] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Debin Tian
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Harini Sooryanarain
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Shannon R. Matzinger
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Phil C. Gauger
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Anbu K. Karuppannan
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Subbiah Elankumaran
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Tanja Opriessnig
- The Roslin Institute, University of Edinburgh, Midlothian, Scotland, UK
| | - Xiang-Jin Meng
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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19
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Afghah Z, Webb B, Meng XJ, Ramamoorthy S. Ten years of PCV2 vaccines and vaccination: Is eradication a possibility? Vet Microbiol 2017; 206:21-28. [DOI: 10.1016/j.vetmic.2016.10.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/02/2016] [Accepted: 10/07/2016] [Indexed: 12/12/2022]
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Porcine Circovirus Type 2 (PCV2) Vaccines in the Context of Current Molecular Epidemiology. Viruses 2017; 9:v9050099. [PMID: 28481275 PMCID: PMC5454412 DOI: 10.3390/v9050099] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 12/30/2022] Open
Abstract
Porcine circovirus type 2 (PCV2) is an economically important swine pathogen and, although small, it has the highest evolution rate among DNA viruses. Since the discovery of PCV2 in the late 1990s, this minimalistic virus with a 1.7 kb single-stranded DNA genome and two indispensable genes has become one of the most important porcine pathogens, and presently is subjected to the highest volume of prophylactic intervention in the form of vaccines in global swine production. PCV2 can currently be divided into five different genotypes, PCV2a through PCV2e. It is well documented that PCV2 continues to evolve, which is reflected by changes in the prevalence of genotypes. During 2006, commercial vaccines for PCV2 were introduced on a large scale in a pig population mainly infected with PCV2b. Since 2012, the PCV2d genotype has essentially replaced the previously predominant PCV2b genotype in North America and similar trends are also documented in other geographic regions such as China and South Korea. This is the second major PCV2 genotype shift since the discovery of the virus. The potential increase in virulence of the emergent PCV2 genotype and the efficacy of the current vaccines derived from PCV2a genotype against the PCV2d genotype viruses has received considerable attention. This review attempts to synthesize the understanding of PCV2 biology, experimental studies on the antigenic variability, and molecular epidemiological analysis of the evolution of PCV2 genotypes.
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21
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Matzinger SR, Opriessnig T, Xiao CT, Catanzaro N, Beach NM, Slade DE, Nitzel GP, Meng XJ. A chimeric virus created by DNA shuffling of the capsid genes of different subtypes of porcine circovirus type 2 (PCV2) in the backbone of the non-pathogenic PCV1 induces protective immunity against the predominant PCV2b and the emerging PCV2d in pigs. Virology 2016; 498:82-93. [DOI: 10.1016/j.virol.2016.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/09/2016] [Accepted: 08/11/2016] [Indexed: 11/30/2022]
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22
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Li J, Yu T, Zhang F, Wang X, Zhou J, Gao X, Gao S, Liu X. Inactivated chimeric porcine circovirus (PCV) 1-2 vaccines based on genotypes 2b and 2d exhibit similar immunological effectiveness in protecting pigs against challenge with PCV2b strain 0233. Arch Virol 2016; 162:235-246. [PMID: 27722993 DOI: 10.1007/s00705-016-3099-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 09/29/2016] [Indexed: 01/27/2023]
Abstract
Porcine circovirus type 2 (PCV2) is subdivided into four genotypes: PCV2a, PCV2b, PCV2c and PCV2d. Here, for the first time, we compared the efficacy of two experimental inactivated chimeric PCV1-2 vaccines based on genotypes 2b and 2d. Seventeen 3-week-old pigs were divided randomly into four groups. Group 1 and 2 pigs were inoculated with genotype 2b- and 2d-based inactivated vaccines, respectively. At 28 days post-vaccination (DPV), pigs in groups 1-3 were challenged with the PCV2b 0233 strain. All experimental pigs were necropsied at 21 days post-challenge (DPC). Pigs vaccinated with the genotype 2b- or 2d-based vaccine had high antibody titres and lower PCV2b copy numbers in samples of sera, faeces and nasal secretions compared with pigs in the unvaccinated challenge group. Interestingly, we detected no DNA from the challenge strain in the superficial inguinal lymph nodes of the pigs immunized with the PCV2b vaccine, while one pig in the PCV2d- immunized group had detectable DNA from the challenge strain at 21 DPC. We found no significant differences in the humoral immune response, PCV2b load, or PCV-related microscopic lesions between the two vaccinated groups post-challenge. Therefore, both vaccines were equally effective at inducing immunity against challenge with PCV2b strain 0233.
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Affiliation(s)
- Jizong Li
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Tianqi Yu
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Feipeng Zhang
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Xiaobo Wang
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Jinzhu Zhou
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Xing Gao
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Song Gao
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.
| | - Xiufan Liu
- Key lab of Avian Bioproducts Development, Ministry of Agriculture, Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
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Huang L, Wang Y, Wei Y, Chen D, Liu D, Du W, Xia D, Wu H, Feng L, Liu C. Capsid proteins from PCV2a genotype confer greater protection against a PCV2b strain than those from PCV2b genotype in pigs: evidence for PCV2b strains becoming more predominant than PCV2a strains from 2000 to 2010s. Appl Microbiol Biotechnol 2016; 100:5933-43. [PMID: 27020283 DOI: 10.1007/s00253-016-7459-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/04/2016] [Accepted: 03/08/2016] [Indexed: 01/10/2023]
Abstract
Two major porcine circovirus type 2 (PCV2) genotypes, PCV2a and PCV2b, are recognized. PCV2a was predominant in the global pig population until 2000 while PCV2b became predominant from 2003 onward. The aim of this study was to analyze the immune protection conferred by two PCV2a and two PCV2b capsid proteins (Caps) in pigs challenged with a mutant PCV2b/YJ (mPCV2b/YJ) strain. Pigs vaccinated with PCV2a/LG-Cap and PCV2a/CL-Cap elicited significantly higher levels of PCV2-specific antibodies and neutralizing antibodies compared with PCV2b/JF-Cap and mPCV2b/YJ-Cap. Following a mPCV2b/YJ challenge, no viremia was detected in the PCV2a/LG-Cap and PCV2a/CL-Cap groups, while viremias were found in 20 and 40 % of the pigs in the PCV2b/JF-Cap and mPCV2b/YJ-Cap groups, respectively. Viral loads in the inguinal lymph nodes of pigs from the PCV2b/JF-Cap and mPCV2b/YJ-Cap groups were significantly higher than those in the PCV2a/LG-Cap and PCV2a/CL-Cap groups, but significantly lower than those of the challenge control group. Furthermore, PCV2 antigens were not detected in the inguinal lymph nodes of pigs from commercial vaccine groups, as well as the PCV2a/LG-Cap and PCV2a/CL-Cap groups, but were found in the challenge control (100 %, 5/5), PCV2b/JF-Cap (20 %, 1/5), and mPCV2b/YJ-Cap (20 %, 1/5) groups. These findings suggest that mPCV2b/YJ-Cap and PCV2b/JF-Cap were less immunogenic than PCV2a/LG-Cap and PCV2a/CL-Cap. We speculate that a genotypic shift from PCV2a to PCV2b might be the result of the majority of PCV2a strains being more immunogenic than the majority of PCV2b strains. These results provide a possible explanation for why PCV2b strains are more likely to cause epidemics than PCV2a strains. It tells us that PCV2 pathogenesis may be associated with its immunogenicity to some extent.
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Affiliation(s)
- Liping Huang
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Yiping Wang
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Yanwu Wei
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Dongjie Chen
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Dan Liu
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Wenjuan Du
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Deli Xia
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Hongli Wu
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Li Feng
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China
| | - Changming Liu
- Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Nangang District, Harbin, 150001, People's Republic of China.
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Zhu X, Liu J, Bai J, Liu P, Zhang T, Jiang P, Wang X. Baculovirus expression of the N-terminus of porcine heat shock protein Gp96 improves the immunogenicity of recombinant PCV2 capsid protein. J Virol Methods 2016; 230:36-44. [PMID: 26826323 DOI: 10.1016/j.jviromet.2016.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 01/23/2016] [Accepted: 01/24/2016] [Indexed: 01/05/2023]
Abstract
Porcine circovirus type 2 (PCV2) causes significant economic losses to the swine industry worldwide. Heat shock proteins (Hsps) can be used as modulators to enhance both innate and adaptive immune responses. In the present study, recombinant baculoviruses expressing the PCV2Cap protein and the N-terminal 22-370 amino acids of porcine Gp96 (Gp96N), Hsp90, and Hsp70 (rBac-cap/Gp96N, rBac-cap/Hsp90 and rBac-cap/Hsp70, respectively) were constructed and the immune responses were examined in mice and piglets. The mouse experiments showed that rBac-cap/Gp96N increased the titers of specific anti-PCV2 neutralizing antibodies, proliferative responses of peripheral blood mononuclear cells (PBMCs) and IFN-γ levels compared to rBac-cap/Hsp90, rBac-cap/Hsp70, or rBac-cap. The pig experiments showed that the levels of anti-PCV2 antibody, proliferative responses of PBMCs, and IFN-γ in the rBac-cap/Gp96N groups were increased compared to those in rBac-cap group. There were no clear clinical signs of infection following PCV2 challenge in pigs inoculated with recombinant rBac-cap/Gp96N and rBac-cap, and the relative daily weight gains were higher than those in the challenge control (CC) group. The pathological lesions, extent of viremia, and viral loads of the vaccinated groups were milder than those in the CC group. Meanwhile, the extent of viremia and viral load present in the rBac-cap/Gp96N group were significantly lower than those in the rBac-cap group. These results indicated that porcine Gp96N effectively increased the humoral and cell-mediated immune responses of PCV2Cap. Gp96N presents an attractive adjuvant or immunotargeting strategy to enhance the protective efficacy of PCV2 subunit vaccines in swine.
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Affiliation(s)
- Xuejiao Zhu
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Jie Liu
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Juan Bai
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Panrao Liu
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Tingjie Zhang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
| | - Ping Jiang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.
| | - Xianwei Wang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
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Xia Z, Yi X, Zhuang Y. Stable over-expression of the human malate–aspartate NADH shuttle member Aralar I in PK15 cells improves energy metabolism and enhances proliferation of porcine circovirus-2. RSC Adv 2016. [DOI: 10.1039/c6ra06343h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The considerable losses sustained by the pig industry due to porcine circovirus-2 (PCV2) could be avoided by using an attenuated vaccine.
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Affiliation(s)
- Zhongwu Xia
- State Key Laboratory of Bioreactor Engineering
- School of Bioengineering
- East China University of Science and Technology
- Shanghai 200237
- China
| | - Xiaoping Yi
- State Key Laboratory of Bioreactor Engineering
- School of Bioengineering
- East China University of Science and Technology
- Shanghai 200237
- China
| | - Yingping Zhuang
- State Key Laboratory of Bioreactor Engineering
- School of Bioengineering
- East China University of Science and Technology
- Shanghai 200237
- China
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26
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Genetic diversity of porcine circovirus type 2 and implications for detection and control. Res Vet Sci 2015; 103:179-86. [DOI: 10.1016/j.rvsc.2015.10.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 09/26/2015] [Accepted: 10/17/2015] [Indexed: 12/26/2022]
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Piñeyro PE, Kenney SP, Giménez-Lirola LG, Opriessnig T, Tian D, Heffron CL, Meng XJ. Evaluation of the use of non-pathogenic porcine circovirus type 1 as a vaccine delivery virus vector to express antigenic epitopes of porcine reproductive and respiratory syndrome virus. Virus Res 2015; 213:100-108. [PMID: 26555162 DOI: 10.1016/j.virusres.2015.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 11/02/2015] [Accepted: 11/04/2015] [Indexed: 11/29/2022]
Abstract
We previously demonstrated that the C-terminus of the capsid gene of porcine circovirus type 2 (PCV2) is an immune reactive epitope displayed on the surface of virions. Insertion of foreign epitope tags in the C-terminus produced infectious virions that elicited humoral immune responses against both PCV2 capsid and the inserted epitope tags, whereas mutation in the N terminus impaired viral replication. Since the non-pathogenic porcine circovirus type 1 (PCV1) shares similar genomic organization and significant sequence identity with pathogenic PCV2, in this study we evaluated whether PCV1 can serve as a vaccine delivery virus vector. Four different antigenic determinants of porcine reproductive and respiratory syndrome virus (PRRSV) were inserted in the C-terminus of the PCV1 capsid gene, the infectivity and immunogenicity of the resulting viruses are determined. We showed that an insertion of 12 (PRRSV-GP2 epitope II, PRRSV-GP3 epitope I, and PRRSV-GP5 epitope I), and 14 (PRRSV-GP5 epitope IV) amino acid residues did not affect PCV1 replication. We successfully rescued and characterized four chimeric PCV1 viruses expressing PRRSV linear antigenic determinants (GP2 epitope II: aa 40-51, ASPSHVGWWSFA; GP3 epitope I: aa 61-72, QAAAEAYEPGRS; GP5 epitope I: aa 35-46, SSSNLQLIYNLT; and GP5 epitope IV: aa 187-200, TPVTRVSAEQWGRP). We demonstrated that all chimeric viruses were stable and infectious in vitro and three chimeric viruses were infectious in vivo. An immunogenicity study in pigs revealed that PCV1-VR2385EPI chimeric viruses elicited neutralizing antibodies against PRRSV-VR2385. The results have important implications for further evaluating PCV1 as a potential vaccine delivery vector.
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Affiliation(s)
- Pablo E Piñeyro
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA; Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 5001, USA
| | - Scott P Kenney
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
| | - Luis G Giménez-Lirola
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 5001, USA
| | - Tanja Opriessnig
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 5001, USA; The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Debin Tian
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
| | - C Lynn Heffron
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
| | - Xiang-Jin Meng
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA.
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28
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Piñeyro PE, Kenney SP, Giménez-Lirola LG, Heffron CL, Matzinger SR, Opriessnig T, Meng XJ. Expression of antigenic epitopes of porcine reproductive and respiratory syndrome virus (PRRSV) in a modified live-attenuated porcine circovirus type 2 (PCV2) vaccine virus (PCV1-2a) as a potential bivalent vaccine against both PCV2 and PRRSV. Virus Res 2015; 210:154-64. [PMID: 26239318 DOI: 10.1016/j.virusres.2015.07.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 07/28/2015] [Accepted: 07/29/2015] [Indexed: 12/01/2022]
Abstract
Co-infection of pigs in the field with porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) is common and poses a major concern in effective control of PCV2 and PRRSV. We previously demonstrated that insertion of foreign epitope tags in the C-terminus of PCV2 ORF2 produced infectious virions that elicited humoral immune responses against both PCV2 capsid and inserted epitope tags. In this study, we aimed to determine whether the non-pathogenic chimeric virus PCV1-2a, which is the basis for the licensed PCV2 vaccine Fostera PCV, can express PRRSV antigenic epitopes, thus generating dual immunity as a potential bivalent vaccine against both PCV2 and PPRSV. Four different linear B-cell antigenic epitopes of PRRSV were inserted into the C-terminus of the capsid gene of the PCV1-2a vaccine virus. We showed that insertion of 12 (PRRSV-GP2 epitope II, PRRSV-GP3 epitope I, and PRRSV-GP5 epitope I), and 14 (PRRSV-GP5 epitope IV) amino acid residues did not impair the replication of the resulting PCV1-2a-PRRSVEPI chimeric viruses in vitro. The four chimeric PCV1-2a viruses expressing PRRSV B-cell linear epitopes were successfully rescued and characterized. An immunogenicity study in pigs revealed that two of the four chimeric viruses, PCV1-2a-PRRSVEPIGP3IG and PCV1-2a-PRRSVEPIEPIGP5IV, elicited neutralizing antibodies against PRRSV VR2385 as well as PCV2 (strains PCV2a, PCV2b, and mPCV2b). The results have important implications for exploring the potential use of PCV1-2a vaccine virus as a live virus vector to develop bivalent MLVs against both PCV2 and PRRSV.
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Affiliation(s)
- Pablo E Piñeyro
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA; Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 5001, USA
| | - Scott P Kenney
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
| | - Luis G Giménez-Lirola
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 5001, USA
| | - C Lynn Heffron
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
| | - Shannon R Matzinger
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA
| | - Tanja Opriessnig
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University College of Veterinary Medicine, Ames, IA 5001, USA; The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Xiang-Jin Meng
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060, USA.
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Li J, Yu T, Wang X, Zhou J, Gao R, Zhang F, Gao X, Gao S, Liu X. Comparative efficacy of experimental inactivated and live-attenuated chimeric porcine circovirus (PCV) 1-2b vaccines derived from PCV1 and PCV2b isolates originated in China. Virol J 2015. [PMID: 26220290 PMCID: PMC4518523 DOI: 10.1186/s12985-015-0338-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Background Porcine circovirus type-2b (PCV2b) is recognized as the etiological agent of the various clinical manifestations of porcine circovirus-associated disease (PCVAD). Previous studies have demonstrated effectiveness of chimeric PCV1-2 vaccines against PCV2b challenge. In this study, the efficacy of inactivated and live-attenuated (2 × 103.5 or 2 × 104.0 50 % tissue culture infective dose [TCID50] dose) chimeric PCV1-2b vaccines was compared side-by-side in conventional pigs. Methods Twenty-seven non-PCV2 viremic pigs without PCV2-specific antibody were randomly divided into six groups, including four vaccinated and challenged groups, a nonvaccinated challenged group, and a mock group. All pigs except those in the mock group were challenged at 28 days post vaccination (DPV) using PCV2b. Results Both inactivated and live-attenuated chimeric PCV1-2b vaccines induced a robust antibody responses, and significantly decreased microscopic lesion and lower viral loads in serum or superficial inguinal lymph nodes (SILN) compared with that in the nonvaccinated challenged group. PCV2 antibody titers decreased after 7 days post challenge (DPC) in pigs administered the inactivated PCV1-2b vaccine and they were lower than those in pigs inoculated with live-attenuated PCV1-2b on the day of necropsy. Moreover, no viremia was present in pigs inoculated with live-attenuated PCV1-2b vaccine at 21 DPC regardless of the dose difference. Conclusions The results demonstrated that both inactivated and live-attenuated chimeric PCV1-2b vaccines were effective to induce protective immunity against PCV2b infection.
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Affiliation(s)
- Jizong Li
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Tianqi Yu
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Xiaobo Wang
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Jinzhu Zhou
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Ruxia Gao
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Feipeng Zhang
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Xing Gao
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Song Gao
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
| | - Xiufan Liu
- Animal Infectious Disease Laboratory, Ministry of Agriculture, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China. .,Jiangsu Co-Innovation Centre for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, 225009, People's Republic of China.
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30
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Wang WC, Zeng ZY, Tang DY, Liang HY, Liu Z, Dai ZJ. Construction of a novel porcine circovirus type 2 infectious clone as a basis for the development of a PCV2 iDNA vaccine. J Virol Methods 2015; 220:21-6. [PMID: 25882478 DOI: 10.1016/j.jviromet.2015.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 04/05/2015] [Accepted: 04/06/2015] [Indexed: 01/15/2023]
Abstract
Porcine circovirus-associated disease is a highly contagious disease that has significant economic consequences. The disease is prevalent in many countries and regions. To generate a genetic marker strain of PCV2, a Sal I restriction enzyme site was inserted into the PCV2 clone as a genetic marker by applying iDNA infectious clone technology. The iDNA represents plasmids that encode the full-length DNA genome of PCV2 assembled in a pcDNA3.1-based vectors. The mutant PCV2 was rescued by transfecting an infectious clone into PK-15 cells and was characterised by an immunoperoxidase monolayer assay (IPMA). The viral genome could be differentiated from the wild-type parent by PCR and restriction fragment length polymorphism (PCR-RFLP). Kunming mice were inoculated with the PCV2 infectious clone or rescued virus via intranasal and intraperitoneal routes. Seroconversion to PCV2-specific antibody appeared in the majority of mice from the two inoculated groups at 7 days postinoculation (DPI), and the specific antibody level was steady for at least 42 days. Viraemia, beginning at 7 DPI and lasting 4 weeks, was detected in the majority of the pigs from the two inoculated groups. The animal experiments revealed that the PCV2 infectious clone and rescued virus both could replicate in mice and induce mice to generate anti-PCV2 antibodies. The infectious clones of PCV2 will be useful for further research investigating a potential tractable iDNA vaccine by reverse genetics technology for attenuated virulance.
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Affiliation(s)
- Wei-Cheng Wang
- College of Animal Sciences, Guizhou University, Guiyang 550025, China.
| | - Zhi-Yong Zeng
- College of Animal Sciences, Guizhou University, Guiyang 550025, China; Key Laboratory of Animal Epidemic Disease and Veterinary Public Health in Guizhou Province, Guiyang 550025, China.
| | - De-Yuan Tang
- College of Animal Sciences, Guizhou University, Guiyang 550025, China
| | - Hai-Ying Liang
- College of Animal Sciences, Guizhou University, Guiyang 550025, China
| | - Zhao Liu
- College of Animal Sciences, Guizhou University, Guiyang 550025, China
| | - Zhen-Jiang Dai
- College of Animal Sciences, Guizhou University, Guiyang 550025, China
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31
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Segalés J. Best practice and future challenges for vaccination against porcine circovirus type 2. Expert Rev Vaccines 2014; 14:473-87. [DOI: 10.1586/14760584.2015.983084] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Joaquim Segalés
- Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
- Departament de Sanitat i d’Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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Optimal transfection methods and comparison of PK-15 and Dulac cells for rescue of chimeric porcine circovirus type 1-2. J Virol Methods 2014; 208:90-5. [DOI: 10.1016/j.jviromet.2014.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 07/29/2014] [Accepted: 08/01/2014] [Indexed: 11/21/2022]
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Wei C, Zhang M, Chen Y, Xie J, Huang Z, Zhu W, Xu T, Cao Z, Zhou P, Su S, Zhang G. Genetic evolution and phylogenetic analysis of porcine circovirus type 2 infections in southern China from 2011 to 2012. INFECTION GENETICS AND EVOLUTION 2013; 17:87-92. [DOI: 10.1016/j.meegid.2013.03.041] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/13/2013] [Accepted: 03/23/2013] [Indexed: 11/15/2022]
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Hua T, Wang X, Bai J, Zhang L, Liu J, Jiang P. Attenuation of porcine circovirus type-2b by replacement with the Rep gene of porcine circovirus type-1. Virus Res 2013; 173:270-9. [PMID: 23454919 DOI: 10.1016/j.virusres.2013.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 02/18/2013] [Accepted: 02/18/2013] [Indexed: 10/27/2022]
Abstract
Porcine circovirus type-2 (PCV2) is the primary causative agent of porcine circovirus-associated diseases and has 4 main ORFs, ORF1 (Rep gene), ORF2 (Cap gene), ORF3 within ORF1, and ORF4, which is overlapped with ORF3, and 1 origin (Ori) of replication located between ORF1 and ORF2. The chimeric PCV1-2, containing the PCV2 capsid, PCV1 rep, and Ori genes, is attenuated in pigs. In order to verify the role of the Rep gene or Ori in the virulence of PCV2, 3 chimeric viruses [PCV2b-Ori1 (PCV1 Ori gene cloned into the backbone of PCV2b), PCV2b-rep1 (PCV1 Rep gene cloned into the backbone of PCV2b), and PCV2b-rep1-Ori1 (PCV1 Rep and Ori genes cloned into the backbone of PCV2b)] and 2 wild-type recombinant PCV2b and PCV1 were constructed and identified. The experimental results in piglets showed that clinical symptoms, viremia, viral load, lesions in lymphoid and lung tissues, and IL-10 and TNF-α expression levels in PBMCs in the PCV2b-rep1-Ori1 and PCV2b-rep1 groups were significantly decreased, compared to PCV2-infected piglets. Meanwhile, histological lesions of lymphoid and lung tissues, viral loads in lymphoid tissues, viremia, and TNF-α expression in PBMCs were not significantly different between groups PCV2b-Ori1 and PCV2b, suggesting that the Rep gene (ORF1) likely contributes to viral pathogenicity in vivo.
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Affiliation(s)
- Tao Hua
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
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35
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Abstract
Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated disease (PCVAD). The virus preferentially targets the lymphoid tissues, which leads to lymphoid depletion and immunosuppression in pigs. The disease is exacerbated by immunostimulation or concurrent infections with other pathogens. PCV2 resides in certain immune cells, such as macrophage and dendritic cells, and modulates their functions. Upregulation of IL-10 and proinflammatory cytokines in infected pigs may contribute to pathogenesis. Pig genetics influence host susceptibility to PCV2, but the viral genetic determinants for virulence remain unknown. PCV2 DNA and proteins interact with various cellular genes that control immune responses to regulate virus replication and pathogenesis. Both neutralizing antibodies and cell-mediated immunity are important immunological correlates of protection. Despite the availability of effective vaccines, variant strains of PCV2 continue to emerge. Although tremendous progress has been made toward understanding PCV2 pathogenesis and immune interactions, many important questions remain.
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Affiliation(s)
- Xiang-Jin Meng
- Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061;
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36
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Opriessnig T, O’Neill K, Gerber PF, de Castro AM, Gimenéz-Lirola LG, Beach NM, Zhou L, Meng XJ, Wang C, Halbur PG. A PCV2 vaccine based on genotype 2b is more effective than a 2a-based vaccine to protect against PCV2b or combined PCV2a/2b viremia in pigs with concurrent PCV2, PRRSV and PPV infection. Vaccine 2013; 31:487-94. [DOI: 10.1016/j.vaccine.2012.11.030] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 10/16/2012] [Accepted: 11/09/2012] [Indexed: 12/26/2022]
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Construction and immunogenicity of recombinant swinepox virus expressing capsid protein of PCV2. Vaccine 2012; 30:6307-13. [DOI: 10.1016/j.vaccine.2012.07.082] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 07/21/2012] [Accepted: 07/30/2012] [Indexed: 11/17/2022]
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38
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Cheung AK. Replicative intermediates of porcine circovirus in animal tissue cultured cells or in bacteria undergoing copy-release replication. Virology 2012; 434:38-42. [PMID: 22939286 DOI: 10.1016/j.virol.2012.08.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/03/2012] [Accepted: 08/14/2012] [Indexed: 10/27/2022]
Abstract
Porcine circovirus (PCV) has been assumed to replicate its genome via the rolling-circle replication (RCR) mechanism because it encodes a Rep protein that contains several amino acid motifs commonly found in other RCR biological systems. Two proteins, Rep and Rep', are essential for PCV DNA replication in mammalian cells. In this work, replicative intermediates of PCV-infected porcine kidney (PK15) cells or copy-release of PCV genomes from a head-to-tail tandem construct (without Rep') in Escherichia coli were examined. In PK15 cells, replicative intermediates consistent with complementary-strand replication which converts single-stranded circular genome to double-stranded supercoiled DNA and RCR which generates single-stranded plus strand progeny genome were observed. To a lesser extent, intermediates suggestive of recombination-dependent replication were also detected. In Escherichia coli, copy release of the single-stranded circular PCV genome with conversion to a supercoiled molecule by complementary-strand synthesis was observed. However, replicative intermediates indicative of RCR were not detected.
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Affiliation(s)
- Andrew K Cheung
- Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA.
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39
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Opriessnig T, Gomes-Neto JC, Hemann M, Shen HG, Beach NM, Huang Y, Halbur PG, Meng XJ. An experimental live chimeric porcine circovirus 1-2a vaccine decreases porcine circovirus 2b viremia when administered intramuscularly or orally in a porcine circovirus 2b and porcine reproductive and respiratory syndrome virus dual-challenge model. Microbiol Immunol 2012; 55:863-73. [PMID: 21951266 DOI: 10.1111/j.1348-0421.2011.00385.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Commercially available inactivated vaccines against porcine circovirus type 2 (PCV2) have been shown to be effective in reducing PCV2 viremia. Live-attenuated, orally administered vaccines are widely used in the swine industry for several pathogens because of their ease of use yet they are not currently available for PCV2 and efficacy. The aims of this study were to determine the efficacy of a live-attenuated chimeric PCV2 vaccine in a dual-challenge model using PCV2b and porcine reproductive and respiratory syndrome virus (PRRSV) and to compare intramuscular (IM) and oral (PO) routes of vaccination. Eighty-three 2-week-old pigs were randomized into 12 treatment groups: four vaccinated IM, four vaccinated PO and four non-vaccinated (control) groups. Vaccination was performed at 3 weeks of age using a PCV1-2a live-attenuated vaccine followed by no challenge, or challenge with PCV2b, PRRSV or a combination of PCV2b and PRRSV at 7 weeks of age. IM administration of the vaccine elicited an anti-PCV2 antibody response between 14 and 28 days post vaccination, 21/28 of the pigs being seropositive prior to challenge. In contrast, the anti-PCV2 antibody response in PO vaccinated pigs was delayed, only 1/27 of the pigs being seropositive at challenge. At 21 days post challenge, PCV2 DNA loads were reduced by 80.4% in the IM vaccinated groups and by 29.6% in the PO vaccinated groups. PCV1-2a (vaccine) viremia was not identified in any of the pigs. Under the conditions of this study, the live attenuated PCV1-2a vaccine was safe and provided immune protection resulting in reduction of viremia. The IM route provided the most effective protection.
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Affiliation(s)
- Tanja Opriessnig
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa 50011, USA.
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40
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Opriessnig T, Langohr I. Current State of Knowledge on Porcine Circovirus Type 2-Associated Lesions. Vet Pathol 2012; 50:23-38. [DOI: 10.1177/0300985812450726] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Porcine circovirus type 2 (PCV2), a small single-stranded DNA virus, was initially discovered in 1998 and is highly prevalent in the domestic pig population. Disease manifestations associated with PCV2 include postweaning multisystemic wasting disease (PMWS), enteric disease, respiratory disease, porcine dermatitis and nephropathy syndrome (PDNS), and reproductive failure. Although these clinical manifestations involve different organ systems, there is considerable overlap in clinical expression of disease and presence of lesions between pigs and within herds. It is now widely accepted that PCV2 can be further subdivided into different types, of which PCV2a and PCV2b are present worldwide and of greatest importance. This review will focus on PCV2-associated lesions in different organ systems.
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Affiliation(s)
- T. Opriessnig
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa
| | - I. Langohr
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan
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41
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Shen HG, Halbur PG, Opriessnig T. Prevalence and phylogenetic analysis of the current porcine circovirus 2 genotypes after implementation of widespread vaccination programmes in the USA. J Gen Virol 2012; 93:1345-1355. [DOI: 10.1099/vir.0.039552-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
To determine the prevalence of porcine circovirus 2 (PCV2) genotypes in the USA during 2010–2011, 5 years after widespread PCV2 vaccination, serum samples from clinically normal pigs that were PCV2 vaccinated (n = 1177), non-vaccinated (n = 378) or of unknown vaccination status (n = 120), and 100 lung samples from pigs diagnosed with PCV-associated disease (PCVAD) were tested. The presence of PCV2, PCV1, PCV1-2a and porcine parvovirus (PPV) DNA was determined by PCR. Determination of the PCV2 genotype was done by differential PCR and sequencing. The prevalence of PCV2a and PCV2b in serum samples was 7.7 % (129/1675) and 8.4 % (141/1675), respectively. PCV2a DNA was only detected in non-vaccinated pigs. For the 100 PCVAD pigs, the prevalence of PCV2a and PCV2b in lung tissues was 13.0 and 65.0 %, respectively. Partial PCV2 ORF2 sequences (9–563 nt) were obtained from 85 PCV2 DNA-positive samples (24 normal pigs and 61 PCVAD cases). Phylogenetic analysis revealed that 12.9 % (11/85) of the sequences belonged to the 2E clade and the PCV2a genotype and 87.1 % (74/85) belonged to the 1B clade and the PCV2b genotype. The alignment of putative PCV2 capsid amino acid sequences revealed possible recombination or mutation between PCV2a and PCV2b genotypes. Chimeric PCV1-2a was not detected in any of the samples and the prevalence rates of PCV1 and PPV were low. Our results suggest PCV2b is more prevalent than PCV2a in PCVAD cases and in vaccinated herds PCV2b circulation is common. The data generated in this study provide novel information on the distribution of PCV2 genotypes in vaccinated pig populations.
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Affiliation(s)
- Hui-Gang Shen
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Patrick G. Halbur
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Tanja Opriessnig
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
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42
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Antigenic subtyping and epitopes’ competition analysis of porcine circovirus type 2 using monoclonal antibodies. Vet Microbiol 2012; 157:13-22. [DOI: 10.1016/j.vetmic.2011.11.030] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 11/17/2011] [Accepted: 11/25/2011] [Indexed: 11/22/2022]
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43
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Opriessnig T, Gauger PC, Faaberg KS, Shen H, Beach NM, Meng XJ, Wang C, Halbur PG. Effect of porcine circovirus type 2a or 2b on infection kinetics and pathogenicity of two genetically divergent strains of porcine reproductive and respiratory syndrome virus in the conventional pig model. Vet Microbiol 2012; 158:69-81. [PMID: 22406346 PMCID: PMC7117418 DOI: 10.1016/j.vetmic.2012.02.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/03/2012] [Accepted: 02/09/2012] [Indexed: 01/10/2023]
Abstract
To determine differences in infection kinetics of two temporally and genetically different type 2 porcine reproductive and respiratory syndrome virus (PRRSV) isolates in vivo with and without concurrent porcine circovirus (PCV) type 2a or 2b infection, 62 pigs were randomly assigned to one of seven groups: negative controls (n=8); pigs coinfected with a 1992 PRRSV strain (VR-2385) and PCV2a (CoI-92-2a; n=9), pigs coinfected with VR-2385 and PCV2b (CoI-92-2b; n=9), pigs coinfected with a 2006 PRRSV strain (NC16845b) and PCV2a (CoI-06-2a; n=9), pigs coinfected with NC16845b and PCV2b (CoI-06-2b; n=9), pigs infected with VR-2385 (n=9), and pigs infected with NC16845b (n=9). Blood samples were collected before inoculation and at day post-inoculation (dpi) 3, 6, 9 and 12 and tested for the presence of PRRSV antibody and RNA, PCV2 antibody and DNA, complete blood counts, and interferon gamma (IFN-γ) levels. Regardless of concurrent PCV2 infection, VR-2385 initially replicated at higher levels and reached peak replication levels at dpi 6. Pigs infected with VR-2385 had significantly higher amounts of viral RNA in serum on both dpi 3 and dpi 6, compared to pigs infected with NC16845b. The peak of NC16845b virus replication occurred between dpi 9 and dpi 12 and was associated with a delayed anti-PRRSV antibody response in these pigs. PCV2 coinfection resulted in significantly more severe macroscopic and microscopic lung lesions and a stronger anti-PRRSV IgG response compared to pigs infected with PRRSV alone. This work further emphasizes in vivo replication differences among PRRSV strains and the importance of coinfecting pathogens.
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Affiliation(s)
- Tanja Opriessnig
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
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44
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Sinha A, Lin K, Hemann M, Shen H, Beach NM, Ledesma C, Meng XJ, Wang C, Halbur PG, Opriessnig T. ORF1 but not ORF2 dependent differences are important for in vitro replication of PCV2 in porcine alveolar macrophages singularly or coinfected with PRRSV. Vet Microbiol 2012; 158:95-103. [PMID: 22406345 DOI: 10.1016/j.vetmic.2012.02.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 02/06/2012] [Accepted: 02/09/2012] [Indexed: 02/08/2023]
Abstract
The objective of this study was to investigate cytokine expression and in vitro replication of porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) in pulmonary alveolar macrophages (PAMs) emphasizing PCV2 open-reading frame (ORF) origin (PCV2a or PCV2b) and PRRSV strain. Chimeric PCV2 viruses composed of different combinations of ORF1 and ORF2 of PCV2a or PCV2b (chimera PCV2a-2b and chimera PCV2b-2a) were constructed and five different PRRSV isolates were utilized: Type 1 (SD 01-08) or type 2 (NC16845b, VR-2332, MN-184, JA-142). PAMs were infected singularly or with combinations of PCV2b, PCV2a, chimera PCV2a-2b, and chimera PCV2b-2a, and one of the five PRRSV isolates. Real-time PCR was used to test PAMs (PCV2 mRNA) and supernatants (PRRSV RNA, PCV2 DNA, PCV2 mRNA) harvested at 24, 48, 72 and 96h post inoculation (hpi). Levels of IFN-γ, TNF-α and IL-10 were determined by quantitative ELISAs. PCV2 replication in PAMs was limited to groups inoculated with PCV2 strains containing ORF1 of PCV2a (PCV2a, chimera PCV2a-2b). Furthermore, in supernatants, PCV2 mRNA was only detected in groups coinfected with PRRSV regardless of strain at 48hpi supporting an enhancing effect of PRRSV on PCV2 infection. Changes in cytokine levels were minimal and associated with PRRSV strain for TNF-α. In summary, in vitro differences in PCV2 replication in PAMs inoculated with different PCV2-PRRSV combinations were independent of PCV2 ORF2 origin with minimal effects of concurrent PRRSV infection perhaps indicating that PCV2-specific changes in ORF1 may be more important than those in ORF2.
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Affiliation(s)
- Avanti Sinha
- Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA
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45
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Hemann M, Beach NM, Meng XJ, Halbur PG, Opriessnig T. Vaccination with inactivated or live-attenuated chimeric PCV1-2 results in decreased viremia in challenge-exposed pigs and may reduce transmission of PCV2. Vet Microbiol 2012; 158:180-6. [PMID: 22341313 DOI: 10.1016/j.vetmic.2012.01.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 01/13/2012] [Accepted: 01/19/2012] [Indexed: 11/29/2022]
Abstract
The objectives were to determine transmissibility of PCV2 to naïve contact pigs 140 days after infection of resident pigs and the benefit of vaccination with live-attenuated or inactivated chimeric PCV2 vaccines on chronic PCV2 infection. Twelve 6-week old PCV2 naïve pigs were randomly divided into four groups of three pigs: negative controls, positive controls, and pigs vaccinated with either a live-attenuated or inactivated chimeric PCV1-2 vaccine. All animals were bled weekly and tested for anti-PCV2 antibodies and PCV2 and PCV1-2 DNA and all groups except negative controls were challenged at 10 weeks. Two pigs vaccinated with the live PCV2 vaccine were PCV1-2 viremic at a single observation point. Both vaccine regimens induced an anti-PCV2 antibody response which was detected sooner and reached a higher level with the commercial inactivated vaccine. Both vaccines significantly decreased the concentration and duration of PCV2 viremia compared to the positive controls. PCV2 DNA was detected in lymphoid tissues of 1/3 pigs in the live-attenuated vaccine group and 3/3 positive control pigs. Three, 2-week old, PCV2 naïve contact pigs were comingled with each group at 168 days post-vaccination or 140 days post-challenge. After seven days of co-housing, the resident pigs were removed and the contact pigs remained for six weeks. Evidence of chimeric PCV1-2 vaccine or PCV2 challenge virus transmission to naïve contact pigs was lacking in all groups. The results of this study suggest that 140-day closure of a small pig population in a controlled environment may result in stabilization and elimination of PCV2.
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Affiliation(s)
- M Hemann
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1600 S. 16th Street, Ames, IA 50011, USA
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46
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Abstract
In the past two decades or so, a number of viruses have emerged in the global swine population. Some, such as porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2), cause economically important diseases in pigs, whereas others such as porcine torque teno virus (TTV), now known as Torque teno sus virus (TTSuV), porcine bocavirus (PBoV) and related novel parvoviruses, porcine kobuvirus, porcine toroviruses (PToV) and porcine lymphotropic herpesviruses (PLHV), are mostly subclinical in swine herds. Although some emerging swine viruses such as swine hepatitis E virus (swine HEV), porcine endogenous retrovirus (PERV) and porcine sapovirus (porcine SaV) may have a limited clinical implication in swine health, they do pose a potential public health concern in humans due to zoonotic (swine HEV) or potential zoonotic (porcine SaV) and xenozoonotic (PERV, PLHV) risks. Other emerging viruses such as Nipah virus, Bungowannah virus and Menangle virus not only cause diseases in pigs but some also pose important zoonotic threat to humans. This article focuses on emerging and re-emerging swine viruses that have a limited or uncertain clinical and economic impact on pig health. The transmission, epidemiology and pathogenic potential of these viruses are discussed. In addition, the two economically important emerging viruses, PRRSV and PCV2, are also briefly discussed to identify important knowledge gaps.
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Affiliation(s)
- X J Meng
- Department of Biomedical Sciences and Pathobiology, Center for Molecular Medicine and Infectious Diseases, College of Veterinary Medicine, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, USA.
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47
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Kumar D, Beach NM, Meng XJ, Hegde NR. Use of PCR-based assays for the detection of the adventitious agent porcine circovirus type 1 (PCV1) in vaccines, and for confirming the identity of cell substrates and viruses used in vaccine production. J Virol Methods 2011; 179:201-11. [PMID: 22079617 DOI: 10.1016/j.jviromet.2011.10.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 10/18/2011] [Accepted: 10/27/2011] [Indexed: 11/25/2022]
Abstract
Safety and quality are important issues for vaccines. Whereas reversion to virulence poses a safety risk with live attenuated vaccines, the potential for the presence of adventitious agents is also an issue of vaccine quality. The recent detection or porcine circovirus type 1 (PCV1) in human vaccines has further highlighted the importance of quality control in vaccine production. The purpose of this study was to use a novel conventional PCR to detect PCV1, and subsequently screen materials used in the manufacture of vaccines at Bharat Biotech International Limited, India. The genome or gene fragments of PCV1 were not detected in any of the vaccines and materials tested, including the live attenuated rotavirus vaccine candidate ROTAVAC(®). Further, the identity of the cells and the viruses used as starting materials in the manufacture of these vaccines was confirmed by species-specific PCR or virus-specific RT-PCR, and no cross-contamination was detected in any case. The methods can be applied for regular in-house quality control screening of raw materials and seeds/banks, as well as formulated vaccines.
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Affiliation(s)
- Deepak Kumar
- Ella Foundation, Genome Valley, Turkapally, Shameerpet Mandal, Hyderabad 500078, India
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48
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Cheung AK. Porcine circovirus: transcription and DNA replication. Virus Res 2011; 164:46-53. [PMID: 22036834 DOI: 10.1016/j.virusres.2011.10.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 10/14/2011] [Accepted: 10/15/2011] [Indexed: 12/18/2022]
Abstract
This review summarizes the molecular studies pertaining to porcine circovirus (PCV) transcription and DNA replication. The genome of PCV is circular, single-stranded DNA and contains 1759-1768 nucleotides. Both the genome-strand (packaged in the virus particle) and the complementary-strand (synthesized in the new host) encode viral proteins. Among a multitude of RNAs synthesized by alternate splicing, only rep and rep' are essential for virus DNA replication via the rolling-circle replication (RCR) mechanism. In contrast to other RCR biological systems which utilize only one multi-functional protein, Rep, to replicate their respective genomes, PCV requires two proteins, Rep and Rep'. During DNA synthesis, the PCV origin of DNA replication (Ori), which contains a pair of inverted repeats (palindrome), exists in a destabilized four-stranded configuration (the melting-pot model) and permits both the palindromic-strand and the complementary-strand to serve as templates simultaneously for initiation and termination. Inherent in the "melting-pot" model is the template-strand-switching mechanism. This mechanism is the basis for the "correction or conversion" of any mutated nucleotide sequences engineered into either arm of the palindrome and the incorporation of "illegitimate recombination" (addition or deletion of nucleotides) events that are commonly observed at the Ori of other RCR biological systems during DNA replication.
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Affiliation(s)
- Andrew K Cheung
- Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010, USA.
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49
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Beach NM, Meng XJ. Efficacy and future prospects of commercially available and experimental vaccines against porcine circovirus type 2 (PCV2). Virus Res 2011; 164:33-42. [PMID: 22005075 DOI: 10.1016/j.virusres.2011.09.041] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 09/30/2011] [Accepted: 09/30/2011] [Indexed: 01/14/2023]
Abstract
Porcine circovirus type 2 (PCV2) is the causative agent of an economically significant collection of disease syndromes in pigs, now known as porcine circovirus associated diseases (PCVADs) in the United States or porcine circovirus diseases (PCVDs) in Europe. Inactivated and subunit vaccines based on PCV2a genotype are commercially available and have been shown to be effective at decreasing mortality and increasing growth parameters in commercial swine herds. Since 2003, there has been a drastic global shift in the predominant prevalence of PCV2b genotype in swine populations, concurrently in most but not all cases with increased severity of clinical disease. Although the current commercial vaccines based on PCV2a do confer cross-protection against PCV2b, novel experimental vaccines based on PCV2b genotype such as modified live-attenuated vaccines are being developed and may provide a superior protection and reduce vaccine costs. In this review, we discuss the current understanding of the impact of PCV2 infection on the host immune response, review the efficacy of the currently available commercial PCV2 vaccines in experimental and field conditions, and provide insight into novel experimental approaches that are useful in the development of next generation vaccines against PCV2.
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Affiliation(s)
- Nathan M Beach
- Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0913, USA
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50
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Multiplex method for simultaneous serological detection of porcine reproductive and respiratory syndrome virus and porcine circovirus type 2. J Clin Microbiol 2011; 49:3184-90. [PMID: 21734031 DOI: 10.1128/jcm.00557-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) are major contributors to the porcine respiratory disease complex (PRDC). Routine serological diagnosis and surveillance play an important role in the prevention of PRDC, as it is a leading cause of economic losses to the swine industry. We herein describe an advanced microsphere-based immunoassay that permits the simultaneous detection of antibodies to PCV2 and PRRSV, thereby reducing the time and effort involved in testing. Recombinant PRRSV nucleoprotein antigen and the PCV2 capsid antigen were coupled to fluorophore-dyed beads with distinct spectral addresses. Weekly serum samples from 72 pigs that were experimentally exposed to either PCV2, PRRSV, or both PCV2 and PRRSV were used to validate the microbead assay (MBA) in comparison with the "gold standard" enzyme-linked immunosorbent assays. The kinetics of the PCV2- and PRRSV-specific antibody responses measured by the microbead assay were comparable to those of the standard assays; Spearman's rank correlations were 0.72 (P < 0.001) for PRRSV and 0.80 (P < 0.001) for PCV2. Diagnostic sensitivity and specificity were determined using field sera whose positive or negative status was determined by the standard tests. The diagnostic sensitivity and specificity were both 98% for PCV2 and were 91% and 93%, respectively, for PRRSV (kappa coefficients, 0.85 and 0.67 for PCV2 and PRRSV, respectively). Multiplexing did not interfere with assay performance or diagnostic sensitivity. Therefore, the described study demonstrates proof of concept for the development of more versatile and economical microbead array-based multiplex serological test panels for veterinary use.
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