Histopathologic and molecular characterization of Erethizon dorsatum papillomavirus 1 and Erethizon dorsatum papillomavirus 2 infection in North American porcupines (Erethizon dorsatum)

Erethizon dorsatum papillomavirus 1 (EdPV1) and Erethizon dorsatum papillomavirus 2 (EdPV2) are associated with cutaneous papillomas in North American porcupines (Erethizon dorsatum). This study defined gross, histopathologic, and molecular characteristics of viral papillomas in 10 North American porcupines submitted to the New York State Animal Health Diagnostic Center. Investigation for the presence of EdPV1 and EdPV2 DNA via polymerase chain reaction (PCR) was performed in 9 of the 10 (90.0%) porcupines, and all porcupines were investigated for the detection and localization of EdPV1 and EdPV2 E6 and E7 nucleic acid via chromogenic in situ hybridization (CISH). Next-generation sequencing (NGS) was performed in 2 porcupines. Papillomas were diagnosed on the muzzle (n = 4), caudal dorsum (n = 1), upper lip (n = 1), chin (n = 1), gingiva (n = 2), and nasal planum (n = 1). Histologically, the lesions consisted of hyperplastic epidermis or epithelium with orthokeratotic keratin, prominent keratohyalin granules, and intranuclear inclusion bodies. PCR identified EdPV1 in 6 of 9 samples and EdPV2 in the remaining 3 samples. NGS resulted in 100% genome coverage of EdPV1 and 76.20% genome coverage of EdPV2 compared with GenBank reference sequences, with 99.8% sequence identity to the complete EdPV2 L1 gene of a novel subtype recently identified in France. Hybridization patterns in 9 of the 10 (90.0%) porcupines were characterized by strong nuclear signals in the superficial epidermis, with strong nuclear and punctate cytoplasmic signals in the stratum spinosum and basale. In one animal, CISH suggested dual EdPV1 and EdPV2 infection.

Co-infection of distinct papillomavirus types in a captive North American porcupine

BACKGROUND

Only two cases of papillomavirus infections in North American porcupines (Erethizon dorsatum) have been described thus far, and molecular investigation linked these cases to two distinct papillomavirus species.

METHODS

In this report, we present the clinical, histological and molecular investigation of a third case of a porcupine papillomavirus infection. Papillomatous lesions occurred on the upper and lower lip of an otherwise healthy three-year old female that was kept in captivity. Within one month, the lesions progressed into exophytic black nodules, followed by a temporary stabilization and ultimately spontaneous regression within seven months of their initial observation. PCR-based screening using specific primers for Erethizon dorsatum papillomavirus 1 and 2 revealed the presence of both these virus types, after which nanopore sequencing was used to determine the complete sequences of the two virus genomes.

RESULTS

One of the genomes shares 99.9% similarity with the only known sequence for Erethizon dorsatum papillomavirus 1, while the second represents a distinct lineage of Erethizon dorsatum papillomavirus 2, sharing only 93.3% similarity with the previously discovered strain.

CONCLUSIONS

This report marks the first observation of a papillomavirus co-infection in a North American porcupine, although the individual contribution of the two virus types to the clinical presentation was not assessed.

IN SITU HYBRIDIZATION AND VIRUS CHARACTERIZATION OF SKUNK ADENOVIRUS IN NORTH AMERICAN WILDLIFE REVEALS MULTISYSTEMIC INFECTIONS IN A BROAD RANGE OF HOSTS

Skunk adenovirus-1 (SkAdV-1) has been reported infecting several North American wildlife species; however, lesions associated with disease have not yet been completely characterized, particularly in porcupines. We describe and characterize the tissue distribution and lesions associated with SkAdV-1 infection in 24 wildlife diagnostic cases submitted between 2015 and 2020, including 16 North American porcupines (Erethizon dorsatum), three striped skunks (Mephitis mephitis), and five raccoons (Procyon lotor), which constitute a new host species. The most common lesion in all species was severe necrotizing bronchopneumonia with (n=12) or without (n=10) interstitial involvement. Intranuclear inclusion bodies were common in respiratory epithelium (n=21) and less often in renal tubular (n=6) and biliary epithelium (n=1). Several cases (n=4) had secondary bacterial infections, including Bordetella bronchiseptica, Pasteurella multocida, and Streptococcus zooepidemicus. In situ hybridization in porcupine (n=6), raccoon (n=1), and skunk (n=1) revealed SkAdV-1 DNA in multiple tissue types, including lung, trachea, turbinates, liver, kidney, lymph node, and brain, and multiple cell types including epithelial, endothelial, and mesothelial cells. These findings were consistent across species. Comparison of viral genomes from a porcupine and a raccoon with that originally isolated from a skunk demonstrated DNA point mutations affecting several viral genes, including the fiber protein gene. Our findings show the spectrum of disease associated with SkAdV-1 infection in a broad host range of wildlife species.

Genomic characterization of Erethizon dorsatum papillomavirus 2, a new papillomavirus species marked by its exceptional genome size

We report here the complete sequence and genome organization of a new papillomavirus, Erethizon dorsatum papillomavirus 2 (EdPV2), which was isolated from cutaneous lesions observed on the muzzle of a North American porcupine. The complete genome is 8809 nucleotides long and encodes five early (E6-E7-E1-E2-E4) and two late proteins (L2-L1). In addition to the upstream regulatory region, the EdPV2 genome contains an exceptionally large secondary non-coding region with no apparent functional relevance. EdPV2 is strongly divergent from the previously described porcupine papillomavirus EdPV1 and phylogenetic analysis shows EdPV2 clustering near members of the genus Pipapillomavirus, a group of rodent papillomaviruses. Pairwise sequence comparison based on the L1 open reading frame identifies Rattus norvegicus papillomavirus 1 as the closest related virus (59.97 % similarity). Based on its low sequence similarity to other known papillomaviruses, EdPV2 is thought to represent a new genus in the family Papillomaviridae.