Use of fluorescence in situ hybridization to detect Felis catus papillomavirus type 2 in feline Bowenoid in situ carcinomas

Papillomaviruses (PVs) are ubiquitous host- and site-specific viruses. PV infections in cats are associated with oral papillomas, viral plaques, Bowenoid in situ carcinomas (BISCs), squamous cell carcinomas and sarcoids; this association is primarily based on PCR detection of PV DNA within said lesions. PV DNA is frequently detectable on normal feline skin; thus, it is possible that some of the implicated DNA is commensal rather than associated with lesion formation. Therefore, the aim of the present study was to use fluorescence in situ hybridization (FISH) to localize PV DNA within feline BISCs, to provide additional evidence that PV infection may influence the development of these neoplasms. FISH probes targeting Felis catus papillomavirus type 2 (FcaPV2) DNA were used to localize FcaPV2 DNA within 42 BISCs from which FcaPV2 DNA had previously been amplified via PCR. Fifteen of 42 BISC lesions (35.7%) demonstrated intralesional FcaPV2 using FISH. Probe annealing was predominantly located within the nuclei of koilocytes found in the upper strata of the epidermis. Probes were typically scattered multifocally within the lesions; most commonly this was near the periphery of the BISCs. These results confirm that a proportion of BISCs contain FcaPV2 DNA. These results further support a causative association between FcaPV2 and BISCs in cats