Psittacid herpesviruses associated with mucosal papillomas in neotropical parrots

Abstract

Mucosal papillomas are relatively common lesions in several species of captive neotropical parrots. They cause considerable morbidity and in some cases, result in mortality. Previous efforts to identify papillomavirus DNA and proteins in these lesions have been largely unsuccessful. In contrast, increasing evidence suggests that mucosal papillomas may contain psittacid herpesviruses (PsHVs). In this study, 41 papillomas from 30 neotropical parrots were examined by PCR with PsHV-specific primers. All 41 papillomas were found to contain PsHV DNA. This 100% prevalence of PsHV infection in the papilloma population was found to be significantly higher than PsHV infection prevalence observed in other surveys of captive parrots. PsHV genotypes 1, 2, and 3, but not 4 were found in these lesions. Psittacus erithacus papillomavirus DNA and finch papillomavirus DNA were not found in the papillomas. A papilloma from a hyacinth macaw (Anodorhynchus hyacinthinus) was found to contain cells that had immunoreactivity to antiserum made to the common antigenic region of human papillomavirus (HPV) L1 major capsid protein. However, four other mucosal papillomas were negative for this immunoreactivity, and negative control tissues from a parrot embryo showed a similar staining pattern to that seen in the cloaca papilloma of the hyacinth macaw, strongly suggesting that the staining seen in hyacinth macaw papilloma was nonspecific. Based on these findings, it was concluded that specific genotypes of PsHV play a direct role in the development of mucosal papillomas of neotropical parrots and there is no evidence to suggest the concurrent presence of a papillomavirus in these lesions.

A Review of DNA Viral Infections in Psittacine Birds

“…These genotypes show distinct biological characteristics and the potential to cause PD [102]. On the other hand, PsHV-1 genotypes 1, 2, and 3, but not 4 have been found in mucosal papillomas [96]. The genotypes detected in PD-affected birds are biased according to bird species and their geographic origins.…”

“…PsHV-1 has also been suggested to have an etiological role in the development of tumors, as specific PsHV-1 genome sequences have been repeatedly detected in mucosal papillomas from parrots [39,64,96]. Recently, another type of psittacid herpesvirus, PsHV-2, has been identified in three African grey parrots.…”

Tissue Distribution of Psittacid Herpesviruses in Latently Infected Parrots, Repeated Sampling of Latently Infected Parrots and Prevalence of Latency in Parrots Submitted for Necropsy

“…8 Some of the parrots latently infected with PsHV-1 genotypes 1, 2, and 3 will subsequently develop PsHV-1 DNA containing papillomas of the mucous membranes of the digestive tract. 11 It is assumed that all parrots latently infected with PsHV-1 shed virus at low levels or shed virus intermittently and are a potential source for infection of naïve parrots and a potential source of Pacheco outbreaks or the spread of mucosal papillomas. 2 Two potential means of preventing PsHV-1 infections include the use of immunization or, alternately, testing for and isolation of infected parrots.…”

“…Studies in parrots with mucosal papillomas suggest that potential sites for PsHV-1 latency are the mucosa of the oral cavity and the cloaca and analyzing samples of these tissues might be a way to detect latently infected parrots. 11 This hypothesis was tested in a preliminary study that used a PCR assay to examine combined oral and cloacal swabs from parrots believed to be latently infected with PsHV-1. In that study, a population of parrots was found that were positive on multiple samples over a period of 12 months.…”

“…Virus was detected in a cutaneous papilloma from one parrot, a mucosal papilloma in another, and the healthy cloacal mucosa of the third. 11 The overall approach to controlling Pacheco disease in an aviary will also depend on the prevalence of infection in populations of parrots and the species that are found to be infected. For example, a serologic survey of aviary parrots in Europe found 6 of 7 aviaries to have positive birds with an overall seroprevalence of 37.3%.…”