Respiratory disease in ball pythons (Python regius) experimentally infected with ball python nidovirus

Highlights: • We demonstrated that nidoviruses cause respiratory disease in ball pythons. • Mucinous chronic inflammation and proliferative interstitial pneumonia is typical. • Infectious virus in oral secretions and feces suggest possible transmission routes. • Choanal and oral/esophageal swabs are good samples for antemortem diagnosis. • Related nidoviruses in lizards and cattle have also been linked to respiratory disease. Circumstantial evidence has linked a new group of nidoviruses with respiratory disease in pythons, lizards, and cattle. We conducted experimental infections in ball pythons (Python regius) to test the hypothesis that ball python nidovirus (BPNV) infection results in respiratory disease. Three ball pythons were inoculated orally and intratracheally with cell culture isolated BPNV and two were sham inoculated. Antemortem choanal, oroesophageal, and cloacal swabs and postmortem tissues of infected snakes were positive for viral RNA, protein, and infectious virus by qRT-PCR, immunohistochemistry, western blot and virus isolation. Clinical signs included oral mucosal reddening, abundant mucus secretions, open-mouthed breathing, and anorexia. Histologic lesions included chronic-active mucinous rhinitis, stomatitis, tracheitis, esophagitis and proliferative interstitial pneumonia. Control snakes remained negative and free of clinical signs throughout the experiment. Our findings establish a causal relationship between nidovirus infection and respiratory disease in ball pythons and shed light on disease progression and transmission.