Serpentovirus (Nidovirus) and Orthoreovirus Coinfection in Captive Veiled Chameleons (Chamaeleo calyptratus) with Respiratory Disease.

Laura Hoon-Hanks,Dawn Evans,Mark Stenglein,Javier Nevarez,Raúl Díaz,Anke Stöhr,Amanda Anderson,Case Rodgers,Roy Parker,Shaun Cross,Halley Steiner

doi:10.3390/v12111329

Abstract

Serpentoviruses are an emerging group of nidoviruses known to cause respiratory disease in snakes and have been associated with disease in other non-avian reptile species (lizards and turtles). This study describes multiple episodes of respiratory disease-associated mortalities in a collection of juvenile veiled chameleons (Chamaeleo calyptratus). Histopathologic lesions included rhinitis and interstitial pneumonia with epithelial proliferation and abundant mucus. Metagenomic sequencing detected coinfection with two novel serpentoviruses and a novel orthoreovirus. Veiled chameleon serpentoviruses are most closely related to serpentoviruses identified in snakes, lizards, and turtles (approximately 40–50% nucleotide and amino acid identity of ORF1b). Veiled chameleon orthoreovirus is most closely related to reptilian orthoreoviruses identified in snakes (approximately 80–90% nucleotide and amino acid identity of the RNA-dependent RNA polymerase). A high prevalence of serpentovirus infection (>80%) was found in clinically healthy subadult and adult veiled chameleons, suggesting the potential for chronic subclinical carriers. Juvenile veiled chameleons typically exhibited a more rapid progression compared to subadults and adults, indicating a possible age association with morbidity and mortality. This is the first description of a serpentovirus infection in any chameleon species. A causal relationship between serpentovirus infection and respiratory disease in chameleons is suspected. The significance of orthoreovirus coinfection remains unknown.

Highlights

A number of viruses cause disease in captive and wild reptiles, and new viral pathogens are continuously being discovered throughout the world [1,2,3]
Gross examination of VC1 revealed a scant amount of stomach contents and empty small intestines and colon, consistent with anorexia
Novel serpentoviruses have recently been found in snake, lizard, and turtle species associated with respiratory or systemic disease, and a serpentovirus has been confirmed as a cause of respiratory disease in pythons [4,5,6,7,9,11,13,14,15,16]

Summary

Introduction

A number of viruses cause disease in captive and wild reptiles, and new viral pathogens are continuously being discovered throughout the world [1,2,3]. Indian pythons (Python molurus), shortly followed by green tree pythons (Morelia viridis) [4,5,6,7]. In these cases, snakes were dying of interstitial proliferative and mucinous pneumonia, tracheitis, and esophagitis. Related serpentoviruses have been discovered in additional snake species, turtles, with or without disease association [10,11,12,13,14,15,16,17]. Serpentoviruses are regarded as significant respiratory pathogens of snakes, but their association with disease in other reptile species is less well established

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