Ball Python Nidovirus: a Candidate Etiologic Agent for Severe Respiratory Disease in Python regius

Abstract

A severe, sometimes fatal respiratory disease has been observed in captive ball pythons (Python regius) since the late 1990s. In order to better understand this disease and its etiology, we collected case and control samples and performed pathological and diagnostic analyses. Electron micrographs revealed filamentous virus-like particles in lung epithelial cells of sick animals. Diagnostic testing for known pathogens did not identify an etiologic agent, so unbiased metagenomic sequencing was performed. Abundant nidovirus-like sequences were identified in cases and were used to assemble the genome of a previously unknown virus in the order Nidovirales. The nidoviruses, which were not previously known to infect nonavian reptiles, are a diverse order that includes important human and veterinary pathogens. The presence of the viral RNA was confirmed in all diseased animals (n = 8) but was not detected in healthy pythons or other snakes (n = 57). Viral RNA levels were generally highest in the lung and other respiratory tract tissues. The 33.5-kb viral genome is the largest RNA genome yet described and shares canonical characteristics with other nidovirus genomes, although several features distinguish this from related viruses. This virus, which we named ball python nidovirus (BPNV), will likely establish a new genus in Torovirinae subfamily. The identification of a novel nidovirus in reptiles contributes to our understanding of the biology and evolution of related viruses, and its association with lung disease in pythons is a promising step toward elucidating an etiology for this long-standing veterinary disease.

Metagenomic Investigation of Idiopathic Meningoencephalomyelitis in Dogs

“…We sequenced and analyzed in parallel a number of known positive samples to validate our approach and to establish limits of detection. These included (1) brain from a captive green tree python positive for python nidovirus; (2) brain from a wild mule deer positive for caprine herpesvirus 2; (3) brain from a wild‐caught American robin experimentally infected with West Nile virus (WNV); and (4) brain from a wild‐caught American crow experimentally infected with WNV . These samples had previously tested positive by metagenomic (green tree python and mule deer) or targeted next‐generation sequencing (crow and robin).…”

“…Additionally, RNA was extracted from postmortem brain samples from a mule deer ( Odocoileus hemionus) , green tree python ( Morelia viridis ), American crow ( Corvus brachyrhynchos ), and American robin ( Turdus migratorius ), all of which had previously been tested by PCR, metagenomic sequencing, or both, and were found to be infected with specific known infectious agents. These were used as positive controls . RNA was extracted using a combination of TRIzol (tissue; Ambion Life Technologies) or TRIzol LS (body fluid; Ambion Life Technologies) with RNA clean and concentrator columns (CC‐5; Zymo Research).…”

Bioinformatics and functional analyses of coronavirus nonstructural proteins involved in the formation of replicative organelles

“…The order Nidovirales includes several families of large RNA viruses, arranged from longest to shortest genome as the Coronaviridae, Roniviridae, Mesoniviridae and Arteriviridae. The Coronaviridae currently contains the Torovirinae and Coronavirinae lineages, though analysis of recently reported divergent toro-like viruses suggests that the Torovirinae may be better represented as an independent family in the Nidovirales (Stenglein et al, 2014). The Coronavirinae currently contains four genera e Alpha-and Betacoronavirus that infect mammals, and Gamma-and Deltacoronavirus that infect birds and mammals.…”

Discovery of a novel nidovirus in cattle with respiratory disease

“…The genus Bafinivirus includes two viruses isolated from fish (White bream virus and White minnow nidovirus) (Batts et al, 2012;Schütze et al, 2006). Within the past year, nidoviruses have been described in pythons with pneumonia [python nidovirus (PNV) and ball python nidovirus (BPNV)] and these viruses are proposed to represent a novel genus within the subfamily Torovirinae (Bodewes et al, 2014;Stenglein et al, 2014;Uccellini et al, 2014). Here, we report on the discovery and genomic characterization of a novel virus that represents a distinctive lineage within this subfamily.…”