Nidoviruses in Reptiles: A Review

Abstract

Since their discovery in 2014, reptile nidoviruses (also known as serpentoviruses) have emerged as significant pathogens worldwide. They are known for causing severe and often fatal respiratory disease in various captive snake species, especially pythons. Related viruses have been detected in other reptiles with and without respiratory disease, including captive and wild populations of lizards, and wild populations of freshwater turtles. There are many opportunities to better understand the viral diversity, species susceptibility, and clinical presentation in different species in this relatively new field of research. In captive snake collections, reptile nidoviruses can spread quickly and be associated with high morbidity and mortality, yet the potential disease risk to wild reptile populations remains largely unknown, despite reptile species declining on a global scale. Experimental studies or investigations of disease outbreaks in wild reptile populations are scarce, leaving the available literature limited mostly to exploring findings of naturally infected animals in captivity. Further studies into the pathogenesis of different reptile nidoviruses in a variety of reptile species is required to explore the complexity of disease and routes of transmission. This review focuses on the biology of these viruses, hosts and geographic distribution, clinical signs and pathology, laboratory diagnosis and management of reptile nidovirus infections to better understand nidovirus infections in reptiles.

Revealing the uncharacterised diversity of amphibian and reptile viruses

“…Adomaviruses are as yet an unconfirmed family of DNA viruses of suspected recombinant origin, and share similar genes with papillomaviruses, polyomaviruses and adenoviruses [ 11 ]. We identified six contigs (range = 265–917 nt) from three viruses with identity to adomaviral genes from a skink ( Scincilla lateralis ) from the USA and two caecilians ( Microcaecilia unicolor and Typhlonectes compressicauda ) from French Guiana (Table 1 & Fig.…”

“…RNA nidoviruses are known to cause a range of severe symptoms including respiratory distress and kidney damage in reptiles [ 10 , 11 , 23 , 50 ]. These viruses comprise families such as Coronaviridae, Arteriviridae and Tobaniviridae .…”

“…The two nidoviruses discovered in this paper, pond slider nidovirus and chameleon serpentovirus phylogenetically cluster close to viruses associated with severe disease in reptiles (Fig. 4 ) [ 11 ]. Specifically, chameleon serpentovirus clusters within the Serpentovirinae subfamily of viruses associated with reptile mortality including Bellinger River virus, Morelia viridis nidovirus of pythons and Shingleback nidovirus 1 (Fig.…”

“…When considering viral threats to amphibians, ranaviruses, large, enveloped DNA viruses, are considered one of the major ecological factors contributing to global population declines [ 9 ]. Nidoviruses, medium-large RNA viruses, are also frequently associated with high-mortality outbreaks in reptiles, for example the Bellinger River turtle was almost rendered extinct in 2015 due to an outbreak likely caused by Bellinger River virus [ 10 , 11 ]. Parvoviruses and circoviruses, small DNA viruses, have lethal associations in reptiles and fish, and were isolated from bearded dragons following mortality events in 2014 and 2020 [ 12 ].…”

Identification of Pseudomonas aeruginosa From the Skin Ulcer Disease of Crocodile Lizards (Shinisaurus crocodilurus) and Probiotics as the Control Measure

“…Among other reptiles, researches mainly focused on larger animals like turtles or snakes. As the spreading of COVID-19, people are more and more aware of the wild or semi-wild breeding animals for any possible pathogens, infection cases among reptiles are reported more frequently these years, such as Salmonella infection, Nematoda infections and Nidovirus infections ( 22 – 29 ). Among these reports, Pseudomonas infections among lizards are reported since decades before.…”