Comparative Genome Analysis of All Nine African Horse Sickness Serotypes Isolated From Equine Fatalities in Kenya and South Africa.
Authors: Hoffmann Bernd, Joseph Sunitha, Patteril Nissy Annie Georgy, Caveney Marina Rodriguez, Elizabeth Shyna K, Muhammed Rubeena, Wernery Renate, Wernery Ulrich
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: African Horse Sickness Virus Genome Analysis African horse sickness remains a significant threat to equine populations across sub-Saharan Africa, caused by nine distinct serotypes of a dsRNA orbivirus that collectively encode seven structural and four non-structural proteins. Researchers sequenced all nine AHSV serotypes from 102 samples collected over two decades from horses that died in seven Kenyan regions, then compared these genomes with South African field isolates to validate the circulating strains and assess their evolutionary relationships. The study confirmed the hypothesised serotypes of the Kenyan field strains and demonstrated substantial genomic homology between Kenyan and South African isolates, indicating relatively stable viral populations across the region. Since the Central Veterinary Research Laboratory in Dubai produces a multivalent inactivated vaccine containing all nine serotypes used in select African countries, this comparative genomic analysis provides critical validation that vaccine formulations remain appropriately matched to naturally circulating virus populations. For equine professionals operating in or moving horses to AHS-endemic areas, these findings support confidence in available vaccination programmes, whilst highlighting the importance of ongoing serological surveillance to detect any future genetic drift that might compromise vaccine effectiveness.
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Practical Takeaways
- •All nine AHSV serotypes circulate in East African equine populations, supporting the use of polyvalent vaccines covering all nine serotypes for protection in endemic regions
- •Genetic similarity between Kenyan and South African AHSV strains suggests vaccination strategies effective in one region may be applicable to the other
- •Practitioners in sub-Saharan Africa should ensure vaccinated horses receive protection against all nine serotypes, as field strains show genetic stability suitable for inactivated vaccine formulation
Key Findings
- •All nine AHSV serotypes were isolated from 102 equine fatality samples collected over 20 years from seven areas in Kenya
- •Newly sequenced AHSV field strains from Kenya showed substantial sequence homologies with recently isolated AHSV field strains from South Africa
- •Genome sequencing confirmed the hypothesized serotypes of AHSV field strains from Kenya
- •CVRL inactivated AHS vaccines containing all nine serotypes demonstrated proven efficacy and safety in previous studies