Search for Equus caballus papillomavirus type 2 in tissues of asymptomatic horses in southern brazil.

Equus caballus papillomavirus type 2 (EcPV-2) has been recently associated with the development of genital squamous cell carcinomas in horses. Nevertheless, its circulation among healthy, asymptomatic horses remains poorly understood. This study aimed to investigate the presence of EcPV-2 DNA in asymptomatic horses submitted to necropsy in southern Brazil. A total of 54 horses without clinical or histological evidence of genital lesions were investigated: 40 necropsied animals and penile mucosa specimens collected from 14 horses at a local abattoir. Tissue samples were subjected to histological analysis and polymerase chain reaction targeting a 306 bp fragment of the EcPV-2 L1 gene. EcPV-2 DNA was detected in one animal (1.85%). The sample was obtained from a necropsied male horse that died due to acute intestinal disease. Sequencing of the amplicon obtained in the PCR confirmed the identity of the viral fragment, and phylogenetic analysis clustered the sequence with known EcPV-2 isolates. No histological lesions were observed in any of the tissues examined from the animal containing amplifiable EcPV-2 DNA. This is the first report of EcPV-2 DNA detection in the genital mucosa of an asymptomatic horse in Brazil, supporting the possibility of subclinical infection. These findings provide initial evidence that EcPV-2 may occur in clinically normal horses in Brazil and highlight the need for further studies to determine the prevalence of subclinical infection and the potential role of asymptomatic carriers in viral transmission.