Search

Gammaherpesvirus infections are ubiquitous in captive and free-ranging ruminants and are associated with a variety of clinical diseases ranging from subclinical or mild inflammatory syndromes to fatal diseases such as malignant catarrhal fever. Gammaherpesvirus infections have been fully characterized in only a few ruminant species, and the overall diversity, host range, and biologic effects of most are not known. This study investigated the presence and host distribution of gammaherpesviruses in ruminant species at two facilities, the San Diego Zoo and San Diego Zoo Safari Park. We tested antemortem (blood, nasal or oropharyngeal swabs) or postmortem (internal organs) samples from 715 healthy or diseased ruminants representing 96 species and subspecies, using a consensus-based herpesvirus PCR for a segment of the DNA polymerase (DPOL) gene. Among the 715 animals tested, 161 (22.5%) were PCR and sequencing positive for herpesvirus, while only 11 (6.83%) of the PCR positive animals showed clinical signs of malignant catarrhal fever. Forty-four DPOL genotypes were identified of which only 10 have been reported in GenBank. The data describe viral diversity within species and individuals, identify host ranges of potential new viruses, and address the proclivity and consequences of interspecies transmission during management practices in zoological parks. The discovery of new viruses with wide host ranges and presence of co-infection within individual animals also suggest that the evolutionary processes influencing Gammaherpesvirus diversity are more complex than previously recognized., Competing Interests: The authors have declared that no competing interests exist.

The roster of amdoparvoviruses (APVs) in small carnivores is growing rapidly, but in most cases, the consequences of infection are poorly understood. Red panda amdoparvovirus (RPAV) is highly prevalent in zoo-housed red pandas and has been detected in both healthy and sick animals. Clarifying the clinical impact of RPAV in this endangered species is critical, and zoological collections offer a unique opportunity to examine viral disease association in carefully managed populations. We evaluated the potential impact of RPAV in captive red pandas with a combination of prospective and retrospective analyses. First, we collected feces from 2 healthy animals from one collection over a 6-year period and detected virus in 72/75 total samples, suggesting that RPAV can be a long-term subclinical infection. We next investigated the infections using a retrospective study of infection status and tissue distribution in a cohort of necropsied animals. We performed polymerase chain reaction and in situ hybridization on 43 necropsy cases from 4 zoo collections (3 from the United States, 1 from Europe, 1997–2022). RPAV was present in these populations for at least 2 decades before its discovery and is detectable in common and significant lesions of zoo-housed red pandas, including myocarditis (3/3 cases), nephritis (9/10), and interstitial pneumonia (2/4). RPAV is also detectable in sporadic lesions, including multisystemic pyogranulomatous inflammation, oral/pharyngeal mucosal inflammation, and dermatitis. The colocalization of virus with lesions supports a role in causation, suggesting that despite the apparently persistent and subclinical carriage of most infections, RPAV may have a significant impact in zoo collections. [ABSTRACT FROM AUTHOR]

Avian poxvirus infections typically manifest as 2 forms: cutaneous ("dry") pox, characterized by proliferative nodules on the skin, and diphtheritic ("wet") pox, characterized by plaques of caseous exudate in the oropharynx and upper respiratory and gastrointestinal tracts. Systemic spread of virus to visceral organs beyond the skin and mucous membranes is rarely reported. Out of 151 cases diagnosed with avian poxvirus over a 20-year period at a zoological institution, 22 were characterized as having systemic involvement based on histopathology and molecular findings. Gross lesions in systemic cases included soft white nodules scattered throughout the liver, spleen, and kidneys. Two histopathologic patterns emerged: (1) widespread histiocytic inflammation in visceral organs with intrahistiocytic viral inclusions and (2) severe, localized dry or wet pox lesions with poxvirus-like inclusions within dermal and subepithelial histiocytes. In situ hybridization targeting the core P4b protein gene confirmed the presence of poxvirus DNA within histiocytes in both patterns. Polymerase chain reaction was performed targeting the reticuloendothelial virus long terminal repeat (REV LTR) flanking region and the core P4b protein gene. Sequences of the REV LTR flanking region from all systemic pox cases were identical to a previously described condorpox virus isolated from an Andean condor with systemic pox. Sequences of the core P4b protein gene from all systemic pox cases grouped into cluster 2 of the B1 subclade of canarypox viruses. Systemic involvement of avian poxvirus likely occurs as a result of infection with certain strain variations in combination with various possible host and environmental factors. [ABSTRACT FROM AUTHOR]

Viral metagenomic analysis of the liver of a black headed python (Aspidites melanocephalus) euthanized for a proliferative spinal lesion of unknown etiology yielded the first characterized genome of a reptile-infecting circovirus (black-headed python circovirus or BhPyCV). BhPyCV-specific in situ hybridization (ISH) showed that viral nucleic acids were strongly expressed in the intestinal lining and mucosa and multifocally in the liver. To investigate the presence of this virus in other snakes and its possible pathogenicity, 17 snakes in the python family with spinal disease were screened with ISH yielding a second BhP positive in intestinal tissue, and a Boelen's python (Morelia boeleni) positive in the liver. BhPyCV specific PCR was used to screen available frozen tissues from 13 of these pythons, four additional deceased pythons with and without spinal disease, and fecal samples from 37 live snakes of multiple species with unknown disease status. PCR detected multiple positive tissues in both of the ISH positive BhP and in the feces of another two live BhP and two live annulated tree boas (Corallus annulatus). Preliminary analysis indicates this circovirus can infect BhPs where it was found in 4/5 BhPs tested (2/2 with spinal disease, 2/3 live with unknown status), Boelen's python (1/2 with spinal disease), and annulated tree boa (2/6 live with unknown status) but was not detected in other python species with the same spinal lesions. This circovirus' causal or contributory role in spinal disease remains speculative and not well supported by these initial data. [ABSTRACT FROM AUTHOR]

Aleutian mink disease virus is the type species in the genus Amdoparvovirus, and in mink and other Mustelidae can cause either subclinical disease or fatal chronic immune stimulation and immune complex disease. The authors describe a novel amdoparvovirus in the endangered red panda (Ailurus fulgens), discovered using viral metagenomics. The authors analyzed the prevalence, tissue distribution, and disease association by PCR, in situ hybridization, electron microscopy, and histology in a group of 6 red pandas from a single zoological collection. The study incorporates a fecal shedding survey and analysis of tissues from 4 necropsied animals over a 12-year span. The tentatively named red panda amdoparvovirus (RpAPV) was detected in the feces and/or tissues of all animals tested. At necropsy of 1 geriatric animal, infection was associated with pyogranulomatous peritonitis, pancreatitis, and myocarditis. Other animals had detectable low-level viral nucleic acid in lymph nodes and both oral and intestinal epithelium at the time of necropsy. Full-length genome sequences of RpAPV strains from 2 animals had 12% sequence divergence, demonstrating genetic diversity even among in-contact animals. RpAPV is a persistent infection in this cohort of red pandas, and has variable clinical expression. [ABSTRACT FROM AUTHOR]