Serotype specific primers and gel-based RT-PCR assays for 'typing' African horse sickness virus: identification of strains from Africa.
Authors: Maan Narender S, Maan Sushila, Nomikou Kyriaki, Belaganahalli Manjunatha N, Bachanek-Bankowska Katarzyna, Mertens Peter P C
Journal: PloS one
Summary
African horse sickness virus (AHSV) presents a significant challenge to equine industries globally, requiring rapid serotype identification to deploy appropriate vaccines, yet traditional neutralisation tests are slow and labour-intensive. Researchers developed targeted gel-based RT-PCR assays that exploit conserved regions within the VP2-encoding segment 2 (Seg-2) of the virus genome, enabling differentiation of all nine AHSV serotypes within 24 hours from blood, tissue, or cultured samples. Evaluation across multiple reference strains demonstrated high specificity with no cross-amplification between closely related serotypes or other orbiviruses such as bluetongue virus and equine encephalosis virus. Beyond rapid diagnosis, the assays generate cDNA suitable for phylogenetic analysis, allowing practitioners and diagnostic laboratories to track strain lineages and identify virus movement patterns across outbreaks in sub-Saharan Africa. For equine professionals managing horses in at-risk regions, this diagnostic advance represents a practical tool for expedited outbreak confirmation and appropriate therapeutic or management responses, whilst contributing epidemiological data essential for understanding AHSV strain distribution and evolution.
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Practical Takeaways
- •Rapid serotype identification via RT-PCR (24 hours) enables faster vaccine selection and deployment compared to traditional virus neutralisation testing, critical for outbreak response
- •These assays facilitate epidemiological tracking of AHSV strains across regions and over time, supporting disease surveillance and control strategies in endemic African countries
- •The assay's specificity eliminates false positives from related orbiviruses, improving diagnostic confidence in horses presenting with clinical signs consistent with AHS
Key Findings
- •Novel gel-based RT-PCR assays targeting AHSV Seg-2 can identify all nine AHSV serotypes with high specificity and without cross-amplification of related viruses (BTV, EEV) within 24 hours
- •Serotype-specific primer sets designed for conserved Seg-2 regions successfully differentiated between AHSV types 1-9 in blood, tissue, and cultured viral samples
- •Generated cDNAs are suitable for sequencing and phylogenetic analysis, enabling identification of distinct virus lineages and strain movement tracking across sub-Saharan African outbreak regions