African horse sickness in The Gambia: circulation of a live-attenuated vaccine-derived strain.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
The research study discovered that the African horse sickness virus, a disease mostly not causing any clinical illness in local horses, has been spreading in The Gambia mainly due to a strain derived from a live-attenuated vaccine.
Introduction
The topic of this research revolves around a virus known as African horse sickness virus serotype 9 (AHSV-9). This virus has been observed to circulate among equids (which includes horses, donkeys, and zebras) in West Africa. It has been noted, however, that the virus typically does not cause any noticeable disease in these local horse populations. The research investigates two theories: either the local breeds of horses are resistant to the disease or the AHSV-9 strains that are on the move are not capable of causing disease (avirulent).
Observations and Findings
- On investigating the situation in The Gambia, the study found that most horses and donkeys (96%) tested positive for African Horse Sickness (AHS). This finding was surprising given most of the animals hadn’t been vaccinated and hadn’t shown any previous signs of AHS.
- Younger horses, those less than 3 years old, were found to have neutralizing antibodies specific to AHSV-9, indicating they had been exposed to the virus.
- Eight of these young equids were also found to be positive for AHSV-9 via serotype-specific RT-PCR, a technique used to amplify and detect specific genetic materials. From two of these horses, live AHSV-9 was successfully isolated.
Conclusion: Vaccine-Derived Strain
The most significant finding from the study came from sequence analysis. The researchers discovered that the AHSV-9 strain present in The Gambia showed 100% identity to Seg-2 of the AHSV-9 reference strain. This discovery strongly indicates that the virus circulating in The Gambia likely originated from a live-attenuated AHSV-9 vaccine strain. Thus, rather than indicating disease resistance among local horse breeds, the widespread seropositivity appears to be due to the circulation of a less harmful, vaccine-derived strain of the virus.
Cite This Article
Publication
Researcher Affiliations
- Institute for Animal Health, Pirbright, Woking, Surrey, UK. chris.oura@bbsrc.ac.uk
MeSH Terms
- African Horse Sickness / epidemiology
- African Horse Sickness Virus / classification
- African Horse Sickness Virus / immunology
- African Horse Sickness Virus / isolation & purification
- Animals
- Antibodies, Neutralizing / blood
- Antibodies, Viral / blood
- Equidae
- Gambia / epidemiology
- Horses
- RNA, Viral / genetics
- RNA, Viral / isolation & purification
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sequence Homology
- Seroepidemiologic Studies
- Serotyping
- Vaccines, Attenuated
- Viral Vaccines
Citations
This article has been cited 6 times.- Ndebé MMF, Mouiche MMM, Moffo F, Poueme RNS, Awah-Ndukum J. Seroprevalence and Risk Factors of African Horse Sickness in Three Agroecological Zones of Cameroon. Vet Med Int 2022;2022:2457772.
- Sullivan E, Lecollinet S, Kerviel A, Hue E, Pronost S, Beck C, Dumarest M, Zientara S, Roy P. Entry-competent-replication-abortive African horse sickness virus strains elicit robust immunity in ponies against all serotypes. Vaccine 2021 May 27;39(23):3161-3168.
- Lulla V, Losada A, Lecollinet S, Kerviel A, Lilin T, Sailleau C, Beck C, Zientara S, Roy P. Protective efficacy of multivalent replication-abortive vaccine strains in horses against African horse sickness virus challenge. Vaccine 2017 Jul 24;35(33):4262-4269.
- Lulla V, Lulla A, Wernike K, Aebischer A, Beer M, Roy P. Assembly of Replication-Incompetent African Horse Sickness Virus Particles: Rational Design of Vaccines for All Serotypes. J Virol 2016 Aug 15;90(16):7405-7414.
- 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.
- Maan NS, Maan S, Nomikou K, Belaganahalli MN, Bachanek-Bankowska K, Mertens PP. Serotype specific primers and gel-based RT-PCR assays for 'typing' African horse sickness virus: identification of strains from Africa. PLoS One 2011;6(10):e25686.