Detection of Vaccinia virus during an outbreak of exanthemous oral lesions in Brazilian equids.
Authors: Abrahão J S, de Souza Trindade G, Pereira-Oliveira G, de Oliveira Figueiredo P, Costa G, Moreira Franco-Luiz A P, Lopes Assis F, Bretas de Oliveira D, Mattos Paim L R, de Araújo Oliveira C E, Lemos Maia Neto A, Geessien Kroon E
Journal: Equine veterinary journal
Summary
# Editorial Summary: Vaccinia Virus Detection in Brazilian Equids In August 2014, a cluster of oral ulcerative disease affected 14 equids (11 donkeys and 3 mules) in Brazil, prompting investigation into whether Vaccinia virus (VACV) was responsible. The research team employed serological testing via plaque-reduction neutralisation assay alongside molecular detection using multiple PCR platforms targeting conserved orthopoxvirus genes (C11R, A56R and A26L), with positive amplicons sequenced and subjected to phylogenetic analysis. Results strongly implicated VACV as the causative agent: neutralising antibodies were detected in 55.5% of animals (titres ≥40 u/ml), and all nine serum samples tested positive for the A56R gene, with 44.4% positive for C11R and 33.3% for A26L; genetic sequencing demonstrated 98.8% identity to Brazilian Group 1 VACV isolates, including characteristic signature deletions. These findings challenge our current understanding of vaccinia epidemiology and suggest equids may play a previously underrecognised role in viral transmission cycles, making systematic surveillance of equine populations in VACV-endemic regions essential for veterinary practitioners managing infectious disease risks in both individual animals and herd health programmes.
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Practical Takeaways
- •Equids can contract Vaccinia virus and present with oral exanthematous lesions; practitioners should be alert to this possibility in outbreak situations
- •VACV-affected equids may pose epidemiological significance in the chain of virus transmission—surveillance and biosecurity protocols are important in areas with known VACV activity
- •Clinical cases with oral lesions in equids should be investigated for orthopoxvirus using molecular methods; serological testing can support diagnosis
Key Findings
- •Vaccinia virus was identified as the aetiological agent in an outbreak affecting 11 donkeys and 3 mules in Brazil in August 2014
- •Neutralising antibodies against orthopoxvirus were detected in 5 of 9 equids (55.5%) with titres ≥40 neutralising u/ml
- •All 9 samples tested positive for orthopoxvirus A56R gene (100%), with 44.4% positive for C11R and 33.3% positive for A26L
- •Viral sequences showed 98.8% identity to Brazilian VACV Group 1 isolates and contained signature deletions characteristic of this group