Molecular typing of equine papillomavirus and autovaccination to treat horses with cutaneous papillomatosis

OBJECTIVE

The aim of this study was to evaluate formalin-inactivated autovaccination to treat cutaneous papillomatosis and to perform molecular typing of the papillomavirus in four horses (two foals, one 3-year-old filly and a 5-year-old stallion).

METHODS

Histopathological slides of lesions were prepared and stained with haematoxylin and eosin (H&E) to establish a diagnosis that was based on observation koilocytosis, which is a pathognomonic cytopathic change that is associated with papillomatosis, using light microscopy. Polymerase chain reaction (PCR) and DNA sequencing were performed using the EPV-R and EPV-F primer set.

RESULTS

In histopathological examination, koilocyte formation and occasional intranuclear viral inclusions were detected in the papillomas. A 334-base pair (bp) fragment of the E2 and L2 genes from the EPV genome was amplified using the EPV-R and EPV-F primer set. This fragment contained 215 bp from the E2 gene and 56 bp from the L2 gene; these were found to be 98.78% to 98.97% identical to the known EcPV type-1 sequence (AF498323).

CONCLUSION

Three horses with cutaneous papillomatosis were administered two doses of a formalin-inactivated preparation of papillomatous lesions at 7-day intervals. The papillomatous lesions were observed to decrease gradually 1 week after the last vaccination, and all warts had resolved within 2-3 weeks. One horse with cutaneous papillomatosis was left as an unvaccinated control, and no changes to the lesions were noted. To the best of our knowledge, this is the first report of EcPV type-1 infection, autovaccine preparation and molecular typing in Turkey.