1
|
Blome S, Moß C, Reimann I, König P, Beer M. Classical swine fever vaccines-State-of-the-art. Vet Microbiol 2017; 206:10-20. [PMID: 28069290 DOI: 10.1016/j.vetmic.2017.01.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 12/24/2016] [Accepted: 01/01/2017] [Indexed: 10/20/2022]
Abstract
Due to its impact on animal health and pig industry, classical swine fever (CSF) is still one of the most important viral diseases of pigs. To control the disease, safe and highly efficacious live attenuated vaccines exist for decades. These vaccines have usually outstanding efficacy and safety but lack differentiability of infected from vaccinated animals (DIVA or marker strategy). In contrast, the first generation of E2 subunit marker vaccines shows constraints in efficacy, application, and production. To overcome these limitations, new generations of marker vaccines are developed. A wide range of approaches have been tried including recombinant vaccines, recombinant inactivated vaccines or subunit vaccines, vector vaccines, and DNA/RNA vaccines. During the last years, especially attenuated deletion vaccines or chimeric constructs have shown potential. At present, especially two new constructs have been intensively tested, the adenovirus-delivered, Semliki Forest virus replicon-vectored marker vaccine candidate "rAdV-SFV-E2" and the pestivirus chimera "CP7_E2alf". The later was recently licensed by the European Medicines Agency. Under field conditions, all marker vaccines have to be accompanied by a potent test system. Particularly this point shows still weaknesses and it is important to embed vaccination in a well-established vaccination strategy and a suitable diagnostic workflow. In summary, conventional vaccines are a standard in terms of efficacy. However, only vaccines with DIVA will allow improved eradication strategies e.g. also under emergency vaccination conditions in free regions. To answer this demand, new generations of marker vaccines have been developed and add now to the tool box of CSF control.
Collapse
Affiliation(s)
- Sandra Blome
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald, Insel Riems, Germany
| | - Claudia Moß
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald, Insel Riems, Germany
| | - Ilona Reimann
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald, Insel Riems, Germany
| | - Patricia König
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald, Insel Riems, Germany
| | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Suedufer 10, 17493 Greifswald, Insel Riems, Germany.
| |
Collapse
|
2
|
Prime-boost vaccine strategy against viral infections: Mechanisms and benefits. Vaccine 2016; 34:413-423. [DOI: 10.1016/j.vaccine.2015.11.062] [Citation(s) in RCA: 157] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 11/21/2015] [Accepted: 11/23/2015] [Indexed: 01/01/2023]
|
3
|
Abstract
Many nonhuman adenoviruses (AdVs) of simian, bovine, porcine, canine, ovine, murine, and fowl origin are being developed as gene delivery systems for recombinant vaccines and gene therapy applications. In addition to circumventing preexisting human AdV (HAdV) immunity, nonhuman AdV vectors utilize coxsackievirus-adenovirus receptor or other receptors for vector internalization, thereby expanding the range of cell types that can be targeted. Nonhuman AdV vectors also provide excellent platforms for veterinary vaccines. A specific nonhuman AdV vector when used in its species of origin could provide an excellent animal model for evaluating the vector efficacy and pathogenesis. These vectors are useful in prime–boost approaches with other AdV vectors or with other gene delivery systems including DNA immunization and viral or bacterial vectors. When multiple vector inoculations are required, nonhuman AdV vectors could supplement HAdV or other viral vectors.
Collapse
|
4
|
Zhang P, Du E, Ma J, Wang W, Zhang L, Tikoo SK, Yang Z. A novel and simple method for rapid generation of recombinant porcine adenoviral vectors for transgene expression. PLoS One 2015; 10:e0127958. [PMID: 26011074 PMCID: PMC4444375 DOI: 10.1371/journal.pone.0127958] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 04/22/2015] [Indexed: 01/02/2023] Open
Abstract
Many human (different serotypes) and nonhuman adenovirus vectors are being used for gene delivery. However, the current system for isolating recombinant adenoviral vectors is either time-consuming or expensive, especially for the generation of recombinant non-human adenoviral vectors. We herein report a new and simple cloning approach for the rapid generation of a porcine adenovirus (PAdV-3) vector which shows promise for gene transfer to human cells and evasion of human adenovirus type 5 (HAdV-5) immunity. Based on the final cloning plasmid, pFPAV3-CcdB-Cm, and our modified SLiCE strategy (SLiCE cloning and lethal CcdB screening), the process for generating recombinant PAdV-3 plasmids required only one step in 3 days, with a cloning efficiency as high as 620 ± 49.56 clones/ng and zero background (100% accuracy). The recombinant PAdV-3 plasmids could be successfully rescued in porcine retinal pigment epithelium cells (VR1BL), which constitutively express the HAdV-5 E1 and PAdV-3 E1B 55k genes, and the foreign genes were highly expressed at 24 h after transduction into swine testicle (ST) cells. In conclusion, this strategy for generating recombinant PAdV-3 vectors based on our modified SLiCE cloning system was rapid and cost-efficient, which could be used as universal cloning method for modification the other regions of PAdV-3 genome as well as other adenoviral genomes.
Collapse
Affiliation(s)
- Peng Zhang
- College of Veterinary Medicine, North-west A&F University, Yangling, Shaanxi, China
| | - Enqi Du
- College of Veterinary Medicine, North-west A&F University, Yangling, Shaanxi, China
| | - Jing Ma
- College of Veterinary Medicine, North-west A&F University, Yangling, Shaanxi, China
| | - Wenbin Wang
- College of Veterinary Medicine, North-west A&F University, Yangling, Shaanxi, China
| | - Lu Zhang
- College of Veterinary Medicine, North-west A&F University, Yangling, Shaanxi, China
| | - Suresh K. Tikoo
- VIDO-InterVac, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Vaccinology & Immunotherapeutics Program, School of Public Health, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- * E-mail: (ZY); (SKT)
| | - Zengqi Yang
- College of Veterinary Medicine, North-west A&F University, Yangling, Shaanxi, China
- * E-mail: (ZY); (SKT)
| |
Collapse
|
5
|
Abstract
Classical swine fever (CSF) is one of the most devastating epizootic diseases of pigs, causing high morbidity and mortality worldwide. The diversity of clinical signs and similarity in disease manifestations to other diseases make CSF difficult to diagnose with certainty. The disease is further complicated by the presence of a number of different strains belonging to three phylogenetic groups. Advanced diagnostic techniques allow detection of antigens or antibodies in clinical samples, leading to implementation of proper and effective control programs. Polymerase chain reaction (PCR)-based methods, including portable real-time PCR, provide diagnosis in a few hours with precision and accuracy, even at the point of care. The disease is controlled by following a stamping out policy in countries where vaccination is not practiced, whereas immunization with live attenuated vaccines containing the 'C' strain is effectively used to control the disease in endemic countries. To overcome the problem of differentiation of infected from vaccinated animals, different types of marker vaccines, with variable degrees of efficacy, along with companion diagnostic assays have been developed and may be useful in controlling and even eradicating the disease in the foreseeable future. The present review aims to provide an overview and status of CSF as a whole with special reference to swine husbandry in India.
Collapse
|
6
|
Vaccines and Vaccination. THE ROLE OF BIOTECHNOLOGY IN IMPROVEMENT OF LIVESTOCK 2015. [PMCID: PMC7122016 DOI: 10.1007/978-3-662-46789-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Livestock vaccines aim to increase livestock product and improve the health and welfare of livestock animals in a cost-efficient manner and prevent disease transmission. Successful livestock vaccines have been generated for pathogens including bacterial, viral, protozoan, and multicellular pathogens. These livestock vaccines have a significant effect on animal health and products and on human health through growing safe food procurement and preventing zoonotic diseases. There are successful production of biotechnological-based animal vaccines licensed for use that include virus-like particle vaccines, gene-deleted marker vaccines, subunit vaccines, DIVA vaccines, and DNA vaccines.
Collapse
|
7
|
Sun Y, Yang Y, Zheng H, Xi D, Lin M, Zhang X, Yang L, Yan Y, Chu X, Bi B. Co-expression of Erns and E2 genes of classical swine fever virus by replication-defective recombinant adenovirus completely protects pigs against virulent challenge with classical swine fever virus. Res Vet Sci 2012; 94:354-60. [PMID: 23092714 DOI: 10.1016/j.rvsc.2012.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 08/13/2012] [Accepted: 09/15/2012] [Indexed: 02/03/2023]
Abstract
The objective of this study was to construct a recombinant adenovirus for future CSFV vaccines used in the pig industry for the reduction of losses involved in CSF outbreaks. The Erns and E2 genes of classical swine fever virus (CSFV), which encode the two main protective glycoproteins from the "Shimen" strain of CSFV, were combined and inserted into the replication-defective human adenovirus type-5 and named the rAd-Erns-E2. Nine pigs were randomly assigned to three treatment groups (three pigs in each group) including the rAd-Erns-E2, hAd-CMV control and DMEM control. Intramuscular vaccination with 2×10(6) TCID(50) of the rAd-Erns-E2 was administered two times with an interval of 21 days. At 42 days post inoculation, pigs in all groups were challenged with a lethal dose of 1×10(3) TCID(50) CSFV "Shimen" strain. Observation of clinical signs was made and the existence of CSFV RNA was detected. Animals in the hAd-CMV and DMEM groups showed severe clinical CSF symptoms and were euthanized from 7 to 10 days after the challenge. However, no adverse clinical CSF signs were observed in vaccinated pigs after the administration of rAd-Erns-E2 and even after CSFV challenge. Neither CSFV RNA nor pathological changes were detected in the tissues of interest of the above vaccinated pigs. These results implied that the recombination adenovirus carrying the Erns-E2 genes could be used to prevent swine from classical swine fever.
Collapse
Affiliation(s)
- Yongke Sun
- Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming 650201, China.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Fowler VL, Barnett PV. Progress in the development of DNA vaccines against foot-and-mouth disease. Expert Rev Vaccines 2012; 11:481-93. [PMID: 22551033 DOI: 10.1586/erv.11.198] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
DNA vaccines are, in principle, the simplest yet most versatile methods of inducing protective humoral and cellular immune responses. Research involving this type of vaccine against veterinary diseases began in the early 1990s and has since seen the evaluation of more than 30 important viral pathogens, including the economically important foot-and-mouth disease. With the demonstration that DNA vaccines protect against foot-and-mouth disease in sheep and pigs, and the advantages these DNA vaccines have over the conventional formulations, this approach may provide a better solution to the control of this disease. In this review, we provide a comprehensive overview of DNA vaccination strategies for foot-and-mouth disease reported in the literature, in which we highlight the studies that have reported protection in the key target species.
Collapse
Affiliation(s)
- Veronica L Fowler
- Institute for Animal Health, Pirbright Laboratory, Surrey GU24 0NF, UK.
| | | |
Collapse
|
9
|
Sun Y, Li N, Li HY, Li M, Qiu HJ. Enhanced immunity against classical swine fever in pigs induced by prime-boost immunization using an alphavirus replicon-vectored DNA vaccine and a recombinant adenovirus. Vet Immunol Immunopathol 2010; 137:20-7. [PMID: 20435352 DOI: 10.1016/j.vetimm.2010.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 02/22/2010] [Accepted: 04/06/2010] [Indexed: 12/12/2022]
Abstract
Classical swine fever (CSF) - caused by the classical swine fever virus (CSFV) - is a fatal disease of pigs that is responsible for extensive losses to the swine industry worldwide. We had demonstrated previously that a prime-boost vaccination strategy using an alphavirus (Semliki Forest virus, SFV) replicon-vectored DNA vaccine (pSFV1CS-E2) and a recombinant adenovirus (rAdV-E2) expressing the E2 glycoprotein of CSFV induced enhanced immune responses in a mouse model. In this study, we evaluated further the efficacy of the heterologous prime-boost immunization approach in pigs, the natural host of CSFV. The results showed that the pigs (n=5) receiving pSFV1CS-E2/rAdV-E2 heterologous prime-boost immunization developed significantly higher titers of CSFV-specific neutralizing antibodies and comparable CD4(+) and CD8(+) T-cell proliferation, compared to the pigs receiving double immunizations with rAdV-E2 alone. When challenged with virulent CSFV Shimen strain, the pigs of the heterologous prime-boost group did not show clinical symptoms or viremia, which were observed in one of the 5 pigs immunized with rAdV-E2 alone and all the 5 control pigs immunized with an empty adenovirus. The results demonstrate that the heterologous DNA prime and recombinant adenovirus boost strategy can induce solid protective immunity.
Collapse
Affiliation(s)
- Yuan Sun
- Division of Swine Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, Heilongjiang, China
| | | | | | | | | |
Collapse
|
10
|
Zhao HP, Sun JF, Li N, Sun Y, Wang Y, Qiu HJ. Prime-boost immunization using alphavirus replicon and adenovirus vectored vaccines induces enhanced immune responses against classical swine fever virus in mice. Vet Immunol Immunopathol 2009; 131:158-66. [DOI: 10.1016/j.vetimm.2009.04.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 03/30/2009] [Accepted: 04/03/2009] [Indexed: 02/06/2023]
|
11
|
Antigen delivery systems for veterinary vaccine development. Viral-vector based delivery systems. Vaccine 2009; 26:6508-28. [PMID: 18838097 PMCID: PMC7131726 DOI: 10.1016/j.vaccine.2008.09.044] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2008] [Revised: 08/21/2008] [Accepted: 09/16/2008] [Indexed: 11/30/2022]
Abstract
The recent advances in molecular genetics, pathogenesis and immunology have provided an optimal framework for developing novel approaches in the rational design of vaccines effective against viral epizootic diseases. This paper reviews most of the viral-vector based antigen delivery systems (ADSs) recently developed for vaccine testing in veterinary species, including attenuated virus and DNA and RNA viral vectors. Besides their usefulness in vaccinology, these ADSs constitute invaluable tools to researchers for understanding the nature of protective responses in different species, opening the possibility of modulating or potentiating relevant immune mechanisms involved in protection.
Collapse
|
12
|
Pretorius A, van Kleef M, Collins N, Tshikudo N, Louw E, Faber F, van Strijp M, Allsopp B. A heterologous prime/boost immunisation strategy protects against virulent E. ruminantium Welgevonden needle challenge but not against tick challenge. Vaccine 2008; 26:4363-71. [DOI: 10.1016/j.vaccine.2008.06.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 05/29/2008] [Accepted: 06/02/2008] [Indexed: 01/03/2023]
|
13
|
Ganges L, Núñez JI, Sobrino F, Borrego B, Fernández-Borges N, Frías-Lepoureau MT, Rodríguez F. Recent advances in the development of recombinant vaccines against classical swine fever virus: cellular responses also play a role in protection. Vet J 2007; 177:169-77. [PMID: 17804267 DOI: 10.1016/j.tvjl.2007.01.030] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 01/24/2007] [Accepted: 01/25/2007] [Indexed: 11/26/2022]
Abstract
Classical swine fever virus (CSFV) is the causative agent of one of the most devastating porcine haemorrhagic viral diseases, classical swine fever (CSF). CSFV mainly infects endothelial cells and macrophages and at the same time promotes bystander apoptosis of the surrounding T cells, causing strong immune suppression and high mortality rates. Most animals experience acute infection, during which they either die or survive by producing neutralising antibodies to the virus. However, in a few cases, the impaired immune system cannot control viral progression, leading to chronic infection. Efficient live attenuated vaccines against CSFV exist and are routinely used only in endemic countries. The ability of these vaccines to replicate in the host, even at very low rates, makes it extremely difficult to distinguish vaccinated from infected animals, favouring a restricted policy regarding vaccination against CSFV in non-endemic countries. There is a clear need for efficient and safer marker vaccines to assist in the control of future CSF outbreaks. In this review article, some of the most recent advances in the field of recombinant vaccines against CSFV are presented and the nature of the protective immune responses they induce is discussed.
Collapse
Affiliation(s)
- Llilianne Ganges
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, INIA, Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
14
|
Wehrle F, Renzullo S, Faust A, Beer M, Kaden V, Hofmann MA. Chimeric pestiviruses: candidates for live-attenuated classical swine fever marker vaccines. J Gen Virol 2007; 88:2247-2258. [PMID: 17622629 DOI: 10.1099/vir.0.82798-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The use of attenuated classical swine fever virus (CSFV) strains as live vaccines is no longer allowed for the control of classical swine fever in Europe, due to the inability to differentiate between infected and vaccinated animals (Differentiating Infected from Vaccinated Animals; DIVA), except as emergency vaccines or as bait vaccines for wild boars. Thus, the establishment of a DIVA vaccine(s) is of pivotal importance for the control of this infectious disease. In this study, recombinant versions of the live-attenuated vaccine strain CSFV Riems were generated by replacing parts of the E2 gene with the corresponding sequence of border disease virus strain Gifhorn. Three cDNA clones were constructed: pRiems-ABC-Gif, pRiems-A-Gif and pRiems-BC-Gif. Infectious particles were obtained from clones pRiems-ABC-Gif and pRiems-BC-Gif only, whereas transfected RNA from clone pRiems-A-Gif behaved like a replicon. Based on its ability to be differentiated in vitro from wild-type CSFV by mAbs, vRiems-ABC-Gif was assessed for immunogenicity and protection against challenge infection in pigs. Before challenge, no CSFV-specific anti-E2 antibodies could be detected with commercial E2-blocking ELISAs in vRiems-ABC-Gif-vaccinated animals, whereas vRiems-vaccinated pigs developed high titres of anti-E2 antibodies, confirming the marker properties of this vaccine candidate. After oral vaccination, only partial protection against challenge infection was observed in the vRiems-ABC-Gif vaccinees, whereas all intramuscularly vaccinated animals and all vRiems-vaccinated animals were fully protected. These experiments suggest that the strategy of exchanging specific antigenic epitopes among pestiviruses is a promising tool for the development of new CSFV marker vaccines.
Collapse
Affiliation(s)
- Franziska Wehrle
- Institute of Virology and Immunoprophylaxis, CH-3147 Mittelhäusern, Switzerland
| | - Sandra Renzullo
- Institute of Virology and Immunoprophylaxis, CH-3147 Mittelhäusern, Switzerland
| | - Anja Faust
- Friedrich-Loeffler-Institut (FLI), Boddenblick 5a, D-17493 Greifswald-Insel Riems, Germany
| | - Martin Beer
- Friedrich-Loeffler-Institut (FLI), Boddenblick 5a, D-17493 Greifswald-Insel Riems, Germany
| | - Volker Kaden
- Friedrich-Loeffler-Institut (FLI), Boddenblick 5a, D-17493 Greifswald-Insel Riems, Germany
| | - Martin A Hofmann
- Institute of Virology and Immunoprophylaxis, CH-3147 Mittelhäusern, Switzerland
| |
Collapse
|
15
|
Voigt H, Merant C, Wienhold D, Braun A, Hutet E, Le Potier MF, Saalmüller A, Pfaff E, Büttner M. Efficient priming against classical swine fever with a safe glycoprotein E2 expressing Orf virus recombinant (ORFV VrV-E2). Vaccine 2007; 25:5915-26. [PMID: 17600594 DOI: 10.1016/j.vaccine.2007.05.035] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 04/18/2007] [Accepted: 05/13/2007] [Indexed: 11/30/2022]
Abstract
An increasing demand in livestock animal husbandry for intervention or emergency vaccination strategies requires a rapid onset of protection linked to prevention of infectious agent spread. Using the new recombinant parapoxvirus (PPV) Orf virus (ORFV) as a vaccine expressing the CSFV E2 glycoprotein we demonstrate that a single intra-muscular application confers solid protection. In the prime only concept, multi-site application of the vector vaccine turned out to be superior to single-site application as no pyrexia occurred after virulent CSFV challenge and CSFV neutralizing serum antibodies regularly were detectable before challenge. Vector virus vaccinated swine were able to cope with the lymphocyte and in particular B-cell depression in peripheral blood after challenge showing no clinical signs and no viremia. Early after challenge CSFV-specific IFN gamma production (IFN-gamma) and high neutralizing serum antibody titers clearly differentiated naïve from vaccinated and protected animals. After CSFV challenge neutralizing serum antibodies titers in vector vaccinated swine were significantly higher than those in sera from live attenuated vaccine primed animals. Horizontal challenge virus transmission was prevented under strict sentinel isolation before mingling but not in next-door stables separated by a wooden barrier at the day of challenge. The presence of CSFV-specific pre-challenge serum antibodies although in low titers is a good prognostic parameter for solid protection after ORFV vector vaccination even when a significant CSFV-specific IFN-gamma production was not detectable before challenge. A heterologous prime-boost regimen as a combination of prime with baculovirus-expressed glycoprotein E2 followed by boost with the parapoxvirus vector turned out to be a better immune stimulant than a homologous prime/boost with the modified live CSFV vaccine. A similar beneficial effect became evident when the challenge infection mimicked the booster vaccination after a single PPV vector prime.
Collapse
Affiliation(s)
- Heiner Voigt
- Friedrich-Loeffler-Institut, Institute for Immunology, Tübingen, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Wang KY, Guo YJ, Zhang YL, Lv K, Sun SH. Combined DNA vaccination against three animal viruses elicits decreased immunogenicity of a single plasmid in mice. Vaccine 2007; 25:4429-36. [PMID: 17420075 DOI: 10.1016/j.vaccine.2007.03.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 03/12/2007] [Accepted: 03/13/2007] [Indexed: 10/23/2022]
Abstract
In order to investigate whether combined DNA vaccines are an ideal way to combine antigens in a single vaccine formulation, we immunized mice with three plasmids (pVSG, pVgD and pVE2), respectively, encoding the antigen of foot-and-mouth disease virus (FMDV), pseudorabies virus (PRV) and classic swine fever virus (CSFV), either alone or in a combined vaccine regimen. We also investigated the immune responses induced by a series of mixtures in which three plasmids were mixed in pairs. Then we further immunized mice with three different plasmids in separate sites and preformed an adoptive transfer experiment. While being given alone, each of the vaccine plasmids induced significant virus-specific antibody responses and splenocytes proliferative activity. But reduced immunogenicity of the pVSG plasmid was found in combined DNA vaccination, no matter whether it was injected in a single or a separate site. Removal single plasmid (pVgD or pVE2) from combined DNA vaccine led to significant increase in the immunogenicity of the pVSG plasmid (P<0.05). And the induction of immune suppression was not mediated by suppressor T cells, as demonstrated by an adoptive transfer experiment. Furthermore, by boosting with whole virus protein of FMDV, mice primed with either pVSG alone or combined DNA vaccine produced statistically significant increase in the FMDV-specific antibody titers (P<0.05). But after boosting, FMDV-specific splenocytes proliferative activity of mice primed with combined DNA vaccine was even lower than that of mice primed with pVSG alone (P<0.05). Taken together, this study reflected the immunogenicity of a single plasmid may be decreased in combined DNA immunization strategy, which still needs to be carefully evaluated before practical application.
Collapse
Affiliation(s)
- Kai-Yu Wang
- Department of Medical Genetics, Second Military Medical University, 800 Xiang'Yin Road, Shanghai 200433, China
| | | | | | | | | |
Collapse
|
17
|
Dong XN, Chen YH. Marker vaccine strategies and candidate CSFV marker vaccines. Vaccine 2007; 25:205-30. [PMID: 16934915 DOI: 10.1016/j.vaccine.2006.07.033] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2006] [Revised: 07/21/2006] [Accepted: 07/21/2006] [Indexed: 11/24/2022]
Abstract
Classical swine fever (CSF) is an economically important highly contagious disease of swine worldwide. Classical swine fever virus (CSFV) is its etiological agent, and the only natural hosts are domestic pigs and wild boars. Although field CSFV strains vary in the virulence, they all result in serious losses in pig industry. Highly virulent field strains generally cause acute disease and high mortality; moderately virulent field strains raise subacute or chronic infections; postnatal infection by low virulent field strains produces subclinical infection and mortality in the new-born piglets. CSFV can cross the placental barrier, and this transplacental transmission usually results in mortality of fetuses and birth of congenitally infected pigs with a late-onset disease and death. Two main strategies to control CSF epidemic are systematic prophylactic vaccination with live attenuated vaccines (such as C-strain) and non-vaccination stamping-out policy. But neither of them is satisfying enough. Marker vaccine and companion serological diagnostic test is thought to be a promising strategy for future control and eradication of CSF. During the past 15 years, various candidate marker vaccines were constructed and evaluated in the animal experiments, including recombinant chimeric vaccines, recombinant deletion vaccines, DNA vaccines, subunit vaccines and peptide vaccines. Among them, two subunit vaccines entered the large scale marker vaccine trial of EU in 1999. Although they failed to fulfil all the demands of the Scientific Veterinary Committee, they successfully induced solid immunity against CSFV in the vaccinated pigs. It can be expected that new potent marker vaccines might be commercially available and used in systematic prophylactic vaccination campaign or emergency vaccination in the next 15 years. Here, we summarized current strategies and candidate CSFV marker vaccines. These strategies and methods are also helpful for the development of new-generation vaccines against other diseases.
Collapse
Affiliation(s)
- Xiao-Nan Dong
- Laboratory of Immunology, Department of Biology, Tsinghua University, Protein Science Laboratory of the Ministry of Education, Beijing 100084, PR China.
| | | |
Collapse
|
18
|
Li N, Qiu HJ, Zhao JJ, Li Y, Wang MJ, Lu BW, Han CG, Hou Q, Wang ZH, Gao H, Peng WP, Li GX, Zhu QH, Tong GZ. A Semliki Forest virus replicon vectored DNA vaccine expressing the E2 glycoprotein of classical swine fever virus protects pigs from lethal challenge. Vaccine 2006; 25:2907-12. [PMID: 17007970 DOI: 10.1016/j.vaccine.2006.08.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 06/24/2006] [Accepted: 08/13/2006] [Indexed: 10/24/2022]
Abstract
Classical swine fever virus (CSFV) causes significant losses in pig industry in many countries in Asia and Europe. The E2 glycoprotein of CSFV is the main target for neutralizing antibodies. Recently, the replicon of alphaviruses, such as Semliki Forest virus (SFV), has been developed as replicative expression vectors for gene delivery. In this study, we constructed a plasmid DNA based on SFV replicon encoding the E2 glycoprotein of CSFV and evaluated its efficacy in rabbits and pigs. The results showed that the animals immunized with the DNA vaccine developed CSFV-specific neutralizing antibodies and were protected from virulent or lethal challenge. This demonstrates that the SFV replicon-derived DNA vaccine can be a potential marker vaccine against CSFV infections.
Collapse
Affiliation(s)
- Na Li
- Division of Swine Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 427 Maduan Street, Harbin 150001, Heilongjiang, China
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Kennedy NJ, Spithill TW, Tennent J, Wood PR, Piedrafita D. DNA vaccines in sheep: CTLA-4 mediated targeting and CpG motifs enhance immunogenicity in a DNA prime/protein boost strategy. Vaccine 2006; 24:970-9. [PMID: 16242220 DOI: 10.1016/j.vaccine.2005.08.076] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 07/20/2005] [Accepted: 08/07/2005] [Indexed: 10/25/2022]
Abstract
DNA vaccines have proven to be an efficient means of inducing immune responses in small laboratory animals; however, their efficacy in large out-bred animal models has been much less promising. In addressing this issue, we have investigated the ability of ovine cytotoxic lymphocyte antigen 4 (CTLA-4) mediated targeting and ruminant specific CpG optimised plasmids, both alone and in combination, to enhance immune responses in sheep to the pro cathepsin B (FhCatB) antigen from Fasciola hepatica. In this study, CTLA-4 mediated targeting enhanced the speed and magnitude of the primary antibody response and effectively primed for a potent memory response compared to conventional DNA vaccination alone, which failed to induce a detectable immune response. While the CpG-augmentation of the CTLA-4 targeted construct did not further enhance the magnitude or isotype profile of the CTLA-4 induced antibody titres, it did result in the induction of significant antigen-specific, lymphocyte-proliferative responses that were not observed in any other treatment group, showing for the first time that significant cellular responses can be induced in sheep following DNA vaccination. In contrast, CpG-augmentation in the absence of CTLA-4 mediated targeting failed to induce a detectable immune response. This is the first study to explore the potential adjuvant effects of ruminant specific CpG motifs on DNA vaccine induced immune responses in sheep. The ability of CpG-augmented CTLA-4 mediated targeting to induce both humoral and cellular immune responses in this study suggests that this may be an effective approach for enhancing the efficacy of DNA vaccines in large out-bred animal models.
Collapse
Affiliation(s)
- Nicholas J Kennedy
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia.
| | | | | | | | | |
Collapse
|
20
|
Zhang S, Guo YJ, Sun SH, Wang KY, Wang KH, Zhang Y, Zhu WJ, Chen ZH, Jiang L. DNA vaccination using bacillus Calmette-Guerin-DNA as an adjuvant to enhance immune response to three kinds of swine diseases. Scand J Immunol 2005; 62:371-7. [PMID: 16253124 DOI: 10.1111/j.1365-3083.2005.01674.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In order to enhance the immune efficacy of DNA vaccination, experiments were conducted to investigate the regulating effects of Bacillus Calmette-Guerin (BCG)-DNA as an adjuvant on immune responses of mice against foot-and-mouth disease (FMD), Aujeszky's disease (AjD) and classical swine fever (CSF). BCG-DNA was purified from BCG by ion-exchange chromatography. Three DNA vaccines (pVSG, pVgD and pVE2) against the respective infection were constructed, and BCG-DNA was coimmunized to mice by muscle injection. The results showed that titres of specific immunoglobulin (Ig)G to the vaccines mounted remarkably in the sera of the adjuvant covaccinated mice (P < 0.01). Antibody isotype IgG2a and IgG1 also increased, respectively, in mice coimmunized with BCG-DNA compared with those of the control groups (P < 0.01). Cellular immune cytokine interferon-gamma and cytotoxic T lymphocytes were detected in coimmunized BCG-DNA groups (P < 0.05). Whereas interleukin-4, humoral immune cytokine, was not significant (P > 0.05). These results suggest that codelivery of BCG-DNA with DNA vaccines against FMD, AjD and CSF can enhance the induction of antigen-specific, especially, cell-mediated immunity.
Collapse
Affiliation(s)
- S Zhang
- Department of Medical Genetics, Second Military Medical University, Shanghai, China
| | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Hammond JM, Johnson MA. Porcine adenovirus as a delivery system for swine vaccines and immunotherapeutics. Vet J 2005; 169:17-27. [PMID: 15683761 PMCID: PMC7128824 DOI: 10.1016/j.tvjl.2003.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2003] [Indexed: 11/02/2022]
Abstract
Porcine adenovirus (PAdV) has many qualities which make it an ideal choice for use as a delivery vector in swine. It is a low grade pathogen, present almost world-wide in a number of serotypes varying in their virulence and tissue tropism, which may allow for serotype specific vaccine targeting. PAdV is species specific having only been isolated from swine, reducing the possibility of its spread to other animals or man following administration. When engineered to contain a foreign gene, recombinant PAdV (rPAdV) can be grown to high titres in tissue culture cells making it cheap to produce. Knowledge of the complete nucleotide sequence of the PAdV genome has enabled rationally directed insertions of foreign genes which remain stably inserted in the genome and can be expressed at high levels following delivery to the target host. Importantly, recombinant PAdV can be administered by injection or by the oral route in feed or drinking water. We have delivered a range of antigens and immunomodulatory molecules to commercially available pigs using rPAdV and found it to be a very effective delivery system. Significantly, recombinant PAdV serotype 3 is highly effective as a delivery vehicle even when administered in the face of high levels of artificially induced serotype specific neutralising antibody to the vector.
Collapse
Affiliation(s)
- Jef M Hammond
- CSIRO, Livestock Industries, Australian Animal Health Laboratory, Private Mail Bag 24, Geelong, Vic. 3220, Australia.
| | | |
Collapse
|
22
|
Manoj S, Babiuk LA, van Drunen Littel-van den Hurk S. Approaches to enhance the efficacy of DNA vaccines. Crit Rev Clin Lab Sci 2004; 41:1-39. [PMID: 15077722 DOI: 10.1080/10408360490269251] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
DNA vaccines consist of antigen-encoding bacterial plasmids that are capable of inducing antigen-specific immune responses upon inoculation into a host. This method of immunization is advantageous in terms of simplicity, adaptability, and cost of vaccine production. However, the entry of DNA vaccines and expression of antigen are subjected to physical and biochemical barriers imposed by the host. In small animals such as mice, the host-imposed impediments have not prevented DNA vaccines from inducing long-lasting, protective humoral, and cellular immune responses. In contrast, these barriers appear to be more difficult to overcome in large animals and humans. The focus of this article is to summarize the limitations of DNA vaccines and to provide a comprehensive review on the different strategies developed to enhance the efficacy of DNA vaccines. Several of these strategies, such as altering codon bias of the encoded gene, changing the cellular localization of the expressed antigen, and optimizing delivery and formulation of the plasmid, have led to improvements in DNA vaccine efficacy in large animals. However, solutions for increasing the amount of plasmid that eventually enters the nucleus and is available for transcription of the transgene still need to be found. The overall conclusions from these studies suggest that, provided these critical improvements are made, DNA vaccines may find important clinical and practical applications in the field of vaccination.
Collapse
Affiliation(s)
- Sharmila Manoj
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Canada
| | | | | |
Collapse
|
23
|
Da'Dara AA, Skelly PJ, Walker CM, Harn DA. A DNA-prime/protein-boost vaccination regimen enhances Th2 immune responses but not protection following Schistosoma mansoni infection. Parasite Immunol 2004; 25:429-37. [PMID: 14651590 DOI: 10.1111/j.1365-3024.2003.00651.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
DNA immunization represents a promising vaccine strategy that has been reasonably successful, and will likely play an even greater role in vaccine development as these vaccines continue to be improved. We have developed a partially protective DNA vaccine against schistosome infection based on a 23-kDa integral membrane protein, Sm23. The focus of this study was to compare immunogenicity and efficacy of vaccination regimens utilizing Sm23 DNA vaccine alone vs. regimens that utilized both Sm23 DNA and Sm23 in recombinant protein form. We found that priming and boosting with the Sm23 DNA construct (Sm23-pcDNA) resulted in a significant level of protection against challenge infection (36-44%). In contrast, altering this protocol by changing the boost from Sm23 DNA to boosting with recombinant Sm23 protein (rSm23) formulated in aluminium hydroxide (alum) failed to induce a significant reduction in worm burdens. Similarly, mice primed and boosted with the rSm23 in alum also did not develop significant levels of protection against challenge infection. We hypothesize that the differences in the ability to drive protective immunity using the DNA prime-DNA boost strategy and the inability to do so when recombinant Sm23 in alum was substituted for Sm23 DNA is due to driving of different immune responses. In support of this, we found that mice primed and boosted with Sm23-pcDNA had Th1-type immune responses characterized by low anti-Sm23 IgG1 : IgG2a antibody isotype ratios, whereas mice boosted with rSm23 had higher IgG1 : IgG2a ratios. In addition, priming and boosting with rSm23 elicited mainly IgG1 antibodies with no detectable IgG2a, indicative of a polarized Th2-type immune response. Thus, similar to our earlier work, the results of this study show that protective vaccination using Sm23 is associated with a Th1 immune response, and efficacy is diminished using protocols that diminish this Th1 bias. In our study, this was likely due to the use of the Th2-driving adjuvant alum, and future studies are planned where we will compare the protective efficacy of rSm23 administered with Th1-type adjuvants.
Collapse
Affiliation(s)
- Akram A Da'Dara
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
| | | | | | | |
Collapse
|
24
|
Smooker PM, Rainczuk A, Kennedy N, Spithill TW. DNA vaccines and their application against parasites--promise, limitations and potential solutions. BIOTECHNOLOGY ANNUAL REVIEW 2004; 10:189-236. [PMID: 15504707 DOI: 10.1016/s1387-2656(04)10007-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
DNA or nucleic acid vaccines are being evaluated for efficacy against a range of parasitic diseases. Data from studies in rodent model systems have provided proof of principle that DNA vaccines are effective at inducing both humoral and T cell responses to a variety of candidate vaccine antigens. In particular, the induction of potent cellular responses often gives DNA vaccination an immunological advantage over subunit protein vaccination. Protection against parasite challenge has been demonstrated in a number of systems. However, application of parasite DNA vaccines in large animals including ruminants, primates and humans has been compromised by the relative lack of immune responsiveness to the vaccines, but the reasons for this hyporesponsiveness are not clear. Here, we review DNA vaccines against protozoan parasites, in particular vaccines for malaria, and the use of genomic approaches such as expression library immunization to generate novel vaccines. The application of DNA vaccines in ruminants is reviewed. We discuss some of the approaches being evaluated to improve responsiveness in large animals including the use of cytokines as adjuvants, targeting molecules as delivery ligands, electroporation and CpG oligonucleotides.
Collapse
Affiliation(s)
- Peter M Smooker
- Department of Biotechnology and Environmental Biology, RMIT University, Bundoora 3083, Australia
| | | | | | | |
Collapse
|
25
|
Abstract
Classical swine fever (CSF) is a serious and contagious viral disease of pigs and wild boar with a widespread worldwide distribution. The immunopathology of the disease is poorly understood, but the ability of the CSF virus to infect cells without triggering apoptosis and to kill uninfected cells is probably highly significant. The virus may be spread by various direct and indirect methods, but in most cases the exact mechanisms involved in local spread between farms are not known. Excellent diagnostic tools and typing methods are available, but tests that could be performed on-farm, in pre-clinically infected pigs or on meat would also be advantageous. A more complete picture of the viruses circulating in different parts of the world is needed. There is great interest to develop and use marker vaccines for the control of CSF in domestic pigs and in wild boar. Epidemiological modelling is increasingly used to evaluate control options.
Collapse
Affiliation(s)
- D J Paton
- Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright, Surrey GU24 0NF, UK.
| | | |
Collapse
|
26
|
Abstract
There are two types of classical swine fever vaccines available: the classical live and the recently developed E2 subunit vaccines. The live Chinese strain vaccine is the most widely used. After a single vaccination, it confers solid immunity within a few days that appears to persist lifelong. The E2 subunit vaccine induces immunity from approximately 10-14 days after a single vaccination. The immunity may persist for more than a year, but is then not complete. The Chinese strain vaccine may establish a strong herd immunity 1-2 weeks earlier than the E2 vaccine. The ability of the Chinese vaccine strain to prevent congenital infection has not been reported, but the E2 subunit vaccine does not induce complete protection against congenital infection. Immunological mechanisms that underlie the protective immunity are still to be elucidated. Both types of vaccine are considered to be safe. A great advantage of the E2 subunit vaccine is that it allows differentiation of infected pigs from vaccinated pigs and is referred to as a DIVA vaccine. However, the companion diagnostic E(rns) ELISA to actually make that differentiation should be improved. Many approaches to develop novel vaccines have been described, but none of these is likely to result in a new DIVA vaccine reaching the market in the next 5-10 years. Countries where classical swine fever is endemic can best control the infection by systematic vaccination campaigns, accompanied by the normal diagnostic procedures and control measures. Oral vaccination of wild boar may contribute to lowering the incidence of classical swine fever, and consequently diminishing the threat of virus introduction into domestic pigs. Free countries should not vaccinate and should be highly alert to rapidly diagnose any new outbreak. Once a new introduction of classical swine fever virus in dense pig areas has been confirmed, an emergency vaccination programme should be immediately instituted, for maximum benefit. The question is whether the time is ripe to seriously consider global eradication of classical swine fever virus.
Collapse
Affiliation(s)
- J T van Oirschot
- Virus Discovery Unit, ID-Lelystad, PO Box 65, 8200 AB, Lelystad, The Netherlands.
| |
Collapse
|
27
|
Pasetti MF, Barry EM, Losonsky G, Singh M, Medina-Moreno SM, Polo JM, Ulmer J, Robinson H, Sztein MB, Levine MM. Attenuated Salmonella enterica serovar Typhi and Shigella flexneri 2a strains mucosally deliver DNA vaccines encoding measles virus hemagglutinin, inducing specific immune responses and protection in cotton rats. J Virol 2003; 77:5209-17. [PMID: 12692223 PMCID: PMC153971 DOI: 10.1128/jvi.77.9.5209-5217.2003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Measles remains a leading cause of child mortality in developing countries. Residual maternal measles antibodies and immunologic immaturity dampen immunogenicity of the current vaccine in young infants. Because cotton rat respiratory tract is susceptible to measles virus (MV) replication after intranasal (i.n.) challenge, this model can be used to assess the efficacy of MV vaccines. Pursuing a new measles vaccine strategy that might be effective in young infants, we used attenuated Salmonella enterica serovar Typhi CVD 908-htrA and Shigella flexneri 2a CVD 1208 vaccines to deliver mucosally to cotton rats eukaryotic expression plasmid pGA3-mH and Sindbis virus-based DNA replicon pMSIN-H encoding MV hemagglutinin (H). The initial i.n. dose-response with bacterial vectors alone identified a well-tolerated dosage (1 x 10(9) to 7 x 10(9) CFU) and a volume (20 micro l) that elicited strong antivector immune responses. Animals immunized i.n. on days 0, 28, and 76 with bacterial vectors carrying DNA plasmids encoding MV H or immunized parenterally with these naked DNA vaccine plasmids developed MV plaque reduction neutralizing antibodies and proliferative responses against MV antigens. In a subsequent experiment of identical design, cotton rats were challenged with wild-type MV 1 month after the third dose of vaccine or placebo. MV titers were significantly reduced in lung tissue of animals immunized with MV DNA vaccines delivered either via bacterial live vectors or parenterally. Since attenuated serovar Typhi and S. flexneri can deliver measles DNA vaccines mucosally in cotton rats, inducing measles immune responses (including neutralizing antibodies) and protection, boosting strategies can now be evaluated in animals primed with MV DNA vaccines.
Collapse
MESH Headings
- Animals
- Antibodies, Viral/blood
- Antigens, Viral/genetics
- Antigens, Viral/immunology
- Disease Models, Animal
- Genetic Vectors
- Hemagglutinins, Viral/genetics
- Hemagglutinins, Viral/immunology
- Immunity, Mucosal
- Measles/immunology
- Measles/prevention & control
- Measles Vaccine/administration & dosage
- Measles Vaccine/genetics
- Measles Vaccine/immunology
- Neutralization Tests
- Salmonella typhi/genetics
- Salmonella typhi/immunology
- Shigella flexneri/genetics
- Shigella flexneri/immunology
- Sigmodontinae
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/immunology
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/immunology
- Viral Plaque Assay
Collapse
Affiliation(s)
- Marcela F Pasetti
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore 21201, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Moennig V, Floegel-Niesmann G, Greiser-Wilke I. Clinical signs and epidemiology of classical swine fever: a review of new knowledge. Vet J 2003; 165:11-20. [PMID: 12618065 DOI: 10.1016/s1090-0233(02)00112-0] [Citation(s) in RCA: 239] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although classical swine fever (CSF) has been well known for decades and epidemics still occur, clinical diagnosis continues to cause problems for veterinary practitioners. This is due to the extensive differential diagnosis, further complicated by the emergence of new diseases such as porcine reproductive and respiratory syndrome (PRRS) and porcine dermatitis and nephropathy syndrome (PDNS). In addition, acute, chronic and prenatal courses of CSF have to be distinguished. As a cause of considerable economical losses within the EU, control of CSF requires knowledge of the primary outbreaks and spread of the disease. Genetic typing of CSF virus isolates has proved to be a potent method of supporting epidemiological investigations. Phylogenetic analysis of CSF virus strains and isolates originating from different continents has allowed three genetic groups and several subgroups within these groups to be distinguished. Whereas isolates belonging to group 3 seem to occur solely in Asia, all CSF virus isolates of the 1990s isolated in the EU belonged to one of the subgroups within group 2 (2.1, 2.2, or 2.3) and were clearly distinct from former CSF reference viruses, which belong to group 1. Within the EU, different strategies are followed for the eradication of CSF in domestic pigs and in wild boar. While a strict non-vaccination policy is followed for domestic pigs, eradication of the disease in wild boar is more complex, and oral immunisation together with special hunting strategies have been applied. Recently, marker vaccines with a companion discriminatory test designed to allow differentiation between vaccinated animals and animals having recovered from field virus infection have been developed. Preliminary studies indicated that the discriminatory tests had a reduced sensitivity and specificity. Further improvements are therefore necessary before marker vaccines can be considered for emergency use in EU Member States. Prevention of CSF remains the main objective within the EU.
Collapse
Affiliation(s)
- V Moennig
- Institute of Virology, School of Veterinary Medicine, Buenteweg 17, D-30559 Hannover, Germany.
| | | | | |
Collapse
|