Molecular identification of papillomavirus in ducks

Abstract

Papillomaviruses infect many vertebrates, including birds. Persistent infections by some strains can cause malignant proliferation of cells (i.e. cancer), though more typically infections cause benign tumours, or may be completely subclinical. Sometimes extensive, persistent tumours are recorded–notably in chaffinches and humans. In 2016, a novel papillomavirus genotype was characterized from a duck faecal microbiome, in Bhopal, India; the sixth papillomavirus genotype from birds. Prompted by this finding, we screened 160 cloacal swabs and 968 faecal samples collected from 299 ducks sampled at Ottenby Bird Observatory, Sweden in 2015, using a newly designed real-time PCR. Twenty one samples (1.9%) from six individuals (2%) were positive. Eighteen sequences were identical to the published genotype, duck papillomavirus 1. One additional novel genotype was recovered from three samples. Both genotypes were recovered from a wild strain domestic mallard that was infected for more than 60 days with each genotype. All positive individuals were adult (P = 0.004). Significantly more positive samples were detected from swabs than faecal samples (P < 0.0001). Sample type data suggests transmission may be via direct contact, and only infrequently, via the oral-faecal route. Infection in only adult birds supports the hypothesis that this virus is sexually transmitted, though more work is required to verify this.

New Insight Into Avian Papillomavirus Ecology and Evolution From Characterization of Novel Wild Bird Papillomaviruses

“…We observed a high estimated prevalence (approximately 30%) of DuPV-3 in the American black duck population and a lower circulation rate in mallard (approximately 10%) with evidence of seasonality in infections. These data are in agreement with previous reports, although infection rates previously documented were lower (1.6% and 12% in mallard and domestic ducks, respectively) (Williams et al, 2018). This difference may be partially explained by the fact that the study by Williams et al (2018) considered only fecal or cloacal swab samples, while our study included paired oropharyngeal and cloacal swabs and we showed in the three cases where we had separated swab samples that DuPV-3 was only detected in the oropharyngeal samples.…”

“…Duck papillomavirus-3 was significantly more prevalent in adult ducks and all DuPV-1- and DuPV-2-positive ducks were adults. Williams et al (2018) hypothesized a possible sexual route of viral transmission, but our data suggest other transmission routes are also likely. The higher infection rate found in adults and during the pre-breeding season could support a sexual route of transmission; however, viruses were also detected in juvenile birds and we showed the virus could be present in the oropharyngeal compartment and not in the cloaca.…”

“…Including those found in this study, four different PVs have now been described in ducks [tribe Anatini within the sub-family Anatinae (Gonzalez et al, 2009)]. The L1 nucleotide sequences of DuPV-1 (Fawaz et al, 2016) and DuPV-2 (Williams et al, 2018) are approximately 92% identical, but only a partial sequence is available and it is not currently possible to evaluate whether they represent two different viral types or two variants of the same type. The two viruses we identified in this study represent two subtypes of the same type (DuPV-3) and, according to the preliminary sequencing data, all three duck viruses belong to the same viral species, possibly within the genus Dyoepsilonpapillomavirus .…”

“…Furthermore, a PV was recently identified in cutaneous lesions of a griffon vulture ( Gyps fulvus ) (Di Francesco et al, 2019) and the Francolinus leucoscepus PV (FlPV-1) was identified on the healthy skin of a yellow-necked francolin (Van Doorslaer et al, 2009). There is also evidence for the existence of mucocutaneous APVs in birds: the Serinus canaria PV (ScPV-1) was detected in the oral cavity of canaries (Truchado et al, 2018a) and three other APV species were identified in cloacal swabs or fecal content of the Adélie penguin [ Pygoscelis adeliae PV-1 (PaPV-1) and -2] and in mallard [ Anas platyrhynchos ; duck PV (DuPV)] (Varsani et al, 2014; Fawaz et al, 2016; Van Doorslaer et al, 2017b; Williams et al, 2018). Two independent studies that analyzed samples from India and Sweden reported identification of the same PV (DuPV-1) in mallard, with a second variant, DuPV-2, observed in the Swedish study only (Fawaz et al, 2016; Williams et al, 2018).…”

Novel papillomavirus in a mallard duck with mesenchymal chondroid dermal tumors

“…7 Although PVs have been reported in fecal and choanal swabs from mallards, no associated lesions have been described, to our knowledge. 4,27 We report here a novel avian PV detected in 2 mesenchymal neoplasms from a mallard duck.…”