Herpesviral, but no papovaviral sequences, are detected in cloacal papillomas of parrots

Internal papillomatosis of parrots (IPP) is a tumour disease with unknown etiology, characterised by progressive development of papillomas in the oral and cloacal mucosa. Based on epidemiologic data, infectious agents, particularly DNA tumour viruses, are considered to be involved. In this study, cloacal papillomas were investigated by PCR for the presence of herpesvirus, papillomavirus and avian polyomavirus genomes, respectively. Using consensus and specific primers, 5 out of 12 papillomas were tested positive for herpesvirus; all papillomas were tested negative for papillomavirus and avian polyomavirus. The DNA sequence of one of the PCR products showed 86.5% homology to the corresponding region of the psittacine herpesvirus 1 DNA polymerase gene. Using a PCR with primers based on this sequence, additional 4 papillomas were tested positive. By in situ hybridisation, herpesviral sequences were detected in epithelial cells of the papilloma, but not in surrounding tissues. As 75% of the tumours proved to be positive, these data suggest an involvement of a herpesvirus in the etiology of IPP; the distinct role, however, needs to be investigated.