Evaluation of the pathogenicity of African Horsesickness (AHS) isolates in vaccinated animals.
Abstract: The polyvalent African Horsesickness (AHS) attenuated live vaccine (ALV) produced by Onderstepoort Biological Products (OBP) Ltd., South Africa, has been associated with some safety concerns and alleged cases of vaccine failure or vaccine-induced disease. The risk of reassortment and reversion to virulence is a common concern associated with the use of ALVs, and a phenomenon reported for viruses with segmented RNA genomes. The purpose of this study was to determine whether or not reassortment of AHS vaccine strains could result in reassortants and reversion to virulence and therefore cause AHS in susceptible horses. Methods: Clinical or field isolates of AHS were obtained from horses with AHS symptoms or disease post vaccination. AHS-naïve horses were inoculated with these isolates and monitored for clinical reactions. Laboratory tests were performed at intervals to determine immune responses and viraemia. Viral RNA extraction and complete genome amplification of monovalent AHS-ALV vaccine strains and isolates collected post-vaccination was conducted. cDNA of the genome segments were run on PAGE to determine mobility patterns and genome segments 2, 3, 4, 5 and 6 sequenced for phylogenetic analysis. Results: No clinical symptoms typical of AHS were observed in inoculated horses and all showed a good immune response. A comparison of mobility patterns of the amplified cDNA genome on PAGE allowed the identification and differentiation of reassortants, which were confirmed by sequence and phylogenetic analysis of the nucleotide sequences. Conclusions: This study, however, showed no indications that vaccine reassortants were pathogenic or lethal after inoculation in susceptible horses. Assumptions of virulence or reversion to virulence of vaccine reassortants post-vaccination in horses could not be substantiated.
Publication Date: 2008-08-03 PubMed ID: 18682269DOI: 10.1016/j.vaccine.2008.07.037Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research explores the safety and effectiveness of the African Horsesickness attenuated live vaccine. Through testing on vaccinated horses, the study finds no evidence that the vaccine can lead to disease outbreak or reversion to a harmful state.
Study Purpose and Methodology
The study aimed to investigate whether the African Horsesickness (AHS) vaccine strain could rearrange its genetic components (reassortment) and become virulent, causing AHS in vaccinated horses. The concern was that the vaccine, rather than providing protection, could potentially lead to illness in the vaccinated animals. The methodology included:
- Gathering of clinical or field isolates from vaccinated horses exhibiting AHS symptoms.
- Inoculation of these isolates into AHS-naïve horses.
- Monitoring of the inoculated horses for any clinical reactions.
- Conducting laboratory tests at different intervals to ascertain immune responses and the presence of the virus in the blood (viraemia).
- Extraction and amplification of vaccine strains’ and post-vaccination isolates’ viral RNA.
- Running the genome segments on a PAGE to determine mobility patterns and subsequent sequencing for phylogenetic analysis.
Results and Conclusions
The study found no clinical symptoms suggestive of AHS in the horses tested with the vaccine. All horses showed a strong immune response. The researchers used mobility patterns of the amplified viral RNA on PAGE to identify and differentiate reassortants. This was confirmed by sequencing the nucleotide sequences.
In conclusion, the research did not find evidence suggesting that the vaccine reassortants were pathogenic or lethal in vaccinated horses. Therefore, it challenges previous assumptions of the vaccine’s potential virulence or reversion to virulence in vaccinated horses, reaffirming the vaccine’s safety and effectiveness.
Cite This Article
APA
von Teichman BF, Smit TK.
(2008).
Evaluation of the pathogenicity of African Horsesickness (AHS) isolates in vaccinated animals.
Vaccine, 26(39), 5014-5021.
https://doi.org/10.1016/j.vaccine.2008.07.037 Publication
Researcher Affiliations
- Research and Development Virology, Onderstepoort Biological Products Ltd., Private Bag X07, Onderstepoort 0110, South Africa. beate@obpvaccines.co.za
MeSH Terms
- African Horse Sickness / immunology
- African Horse Sickness / prevention & control
- African Horse Sickness / virology
- African Horse Sickness Virus / genetics
- African Horse Sickness Virus / immunology
- African Horse Sickness Virus / pathogenicity
- Animals
- Antibodies, Viral / immunology
- DNA, Viral / genetics
- Female
- Genome, Viral
- Horses / immunology
- Horses / virology
- Immunoglobulin G / immunology
- Male
- Reassortant Viruses / genetics
- Reassortant Viruses / immunology
- Reassortant Viruses / pathogenicity
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
- Vaccination
- Vaccines, Attenuated / adverse effects
- Vaccines, Attenuated / immunology
- Viral Vaccines / adverse effects
- Viral Vaccines / immunology
- Viremia / immunology
Citations
This article has been cited 10 times.- Wang Y, Ong J, Ng OW, Songkasupa T, Koh EY, Wong JPS, Puangjinda K, Fernandez CJ, Huangfu T, Ng LC, Chang SF, Yap HH. Development of Differentiating Infected from Vaccinated Animals (DIVA) Real-Time PCR for African Horse Sickness Virus Serotype 1.. Emerg Infect Dis 2022 Dec;28(12):2446-2454.
- Calvo-Pinilla E, Marín-López A, Utrilla-Trigo S, Jiménez-Cabello L, Ortego J. Reverse genetics approaches: a novel strategy for African horse sickness virus vaccine design.. Curr Opin Virol 2020 Oct;44:49-56.
- Rutkowska DA, Mokoena NB, Tsekoa TL, Dibakwane VS, O'Kennedy MM. Plant-produced chimeric virus-like particles - a new generation vaccine against African horse sickness.. BMC Vet Res 2019 Dec 3;15(1):432.
- Dennis SJ, Meyers AE, Hitzeroth II, Rybicki EP. African Horse Sickness: A Review of Current Understanding and Vaccine Development.. Viruses 2019 Sep 11;11(9).
- Aksular M, Calvo-Pinilla E, Marín-López A, Ortego J, Chambers AC, King LA, Castillo-Olivares J. A single dose of African horse sickness virus (AHSV) VP2 based vaccines provides complete clinical protection in a mouse model.. Vaccine 2018 Nov 12;36(46):7003-7010.
- Calvo-Pinilla E, Gubbins S, Mertens P, Ortego J, Castillo-Olivares J. The immunogenicity of recombinant vaccines based on modified Vaccinia Ankara (MVA) viruses expressing African horse sickness virus VP2 antigens depends on the levels of expressed VP2 protein delivered to the host.. Antiviral Res 2018 Jun;154:132-139.
- Dennis SJ, Meyers AE, Guthrie AJ, Hitzeroth II, Rybicki EP. Immunogenicity of plant-produced African horse sickness virus-like particles: implications for a novel vaccine.. Plant Biotechnol J 2018 Feb;16(2):442-450.
- Kanai Y, van Rijn PA, Maris-Veldhuis M, Kaname Y, Athmaram TN, Roy P. Immunogenicity of recombinant VP2 proteins of all nine serotypes of African horse sickness virus.. Vaccine 2014 Sep 3;32(39):4932-7.
- Castillo-Olivares J, Calvo-Pinilla E, Casanova I, Bachanek-Bankowska K, Chiam R, Maan S, Nieto JM, Ortego J, Mertens PP. A modified vaccinia Ankara virus (MVA) vaccine expressing African horse sickness virus (AHSV) VP2 protects against AHSV challenge in an IFNAR -/- mouse model.. PLoS One 2011 Jan 26;6(1):e16503.
- Venter M, Human S, Zaayman D, Gerdes GH, Williams J, Steyl J, Leman PA, Paweska JT, Setzkorn H, Rous G, Murray S, Parker R, Donnellan C, Swanepoel R. Lineage 2 west nile virus as cause of fatal neurologic disease in horses, South Africa.. Emerg Infect Dis 2009 Jun;15(6):877-84.
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