High genetic diversity of equine infectious anaemia virus strains from Slovenia revealed upon phylogenetic analysis of the p15 gag gene region.
Authors: Kuhar U, Malovrh T
Journal: Equine veterinary journal
Summary
# Editorial Summary: High Genetic Diversity of Slovenian EIAV Strains Equine infectious anaemia virus (EIAV) continues to cause sporadic disease across Europe, yet little was known about the genetic characteristics of strains circulating in Slovenia. Kuhar and Malovrh sequenced the p15 gag gene region from 28 EIAV-positive samples derived from post-mortem examinations of horses across 17 farms, then constructed a phylogenetic analysis to determine relationships between these strains and published European isolates. The researchers identified unexpectedly high genetic diversity: the 28 sequences distributed across four distinct monophyletic groups and nine separate branches, with closest relatives to the Italian strains already documented in Europe. Perhaps most significantly, the phylogenetic patterns suggested both within-farm and between-farm transmission events, with some horses on geographically distant farms harbouring virtually identical viral strains. This finding raises important questions about enforcement of EIAV legislation, potential virus reservoirs in pleasure and meat-production horses, and the reliability of screening protocols—particularly the agar gel immunodiffusion test, which may lack sensitivity to detect all infected animals and permit unrecognised disease spread through equine populations.
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Practical Takeaways
- •EIAV surveillance and testing protocols need improvement, as low sensitivity of agar gel immunodiffusion tests may allow infected horses to escape detection and spread infection across farms
- •Multiple EIAV strains circulating in a region suggests poor biosecurity practices and inadequate enforcement of regulations—farms should implement strict quarantine and testing protocols for all new horses
- •The presence of high genetic diversity indicates complex transmission patterns; routine serological screening of riding horses, pleasure horses, and those in meat production chains is critical to control spread
Key Findings
- •28 EIAV sequences from 29 serologically positive horses showed high genetic diversity, distributed across 4 monophyletic groups and 9 branches
- •Slovenian EIAV strains were most closely related to European strains from Italy
- •Multiple farms with distantly located horses and same-farm animals showed evidence of infection with identical EIAV strains, suggesting potential virus reservoirs
- •This represents the first report of such high genetic diversity of EIAV strains within a single country