EcPV2 has been demonstrated to be a causal factor for the development of genital papillomas and squamous cell carcinomas in horses. We are interested in elucidating the pathogenesis and transformation potential of this virus. Clinical samples are collected and characterized by PCR, ELISA, IHC and transcriptome analysis. These investigations reveal the epidemiological distribution of the virus and fundamental molecular events within affected tissue. Since the replication cycle of papillomaviruses is tightly linked to the differentiation of the host tissue, the propagation of these viruses in cell culture is hampered. In another line of experiments, the effects of heterologously expressed EcPV-2 genes are assessed in primary equine keratinocytes as well as in stable cell lines.