Identification, Characterization, and In Vitro Culture of Highly Divergent Arenaviruses from Boa Constrictors and Annulated Tree Boas: Candidate Etiological Agents for Snake Inclusion Body Disease

Abstract

Inclusion body disease (IBD) is an infectious fatal disease of snakes typified by behavioral abnormalities, wasting, and secondary infections. At a histopathological level, the disease is identified by the presence of large eosinophilic cytoplasmic inclusions in multiple tissues. To date, no virus or other pathogen has been definitively characterized or associated with the disease. Using a metagenomic approach to search for candidate etiologic agents in snakes with confirmed IBD, we identified and de novo assembled the complete genomic sequences of two viruses related to arenaviruses, and a third arenavirus-like sequence was discovered by screening an additional set of samples. A continuous boa constrictor cell line was established and used to propagate and isolate one of the viruses in culture. Viral nucleoprotein was localized and concentrated within large cytoplasmic inclusions in infected cells in culture and tissues from diseased snakes. In total, viral RNA was detected in 6/8 confirmed IBD cases and 0/18 controls. These viruses have a typical arenavirus genome organization but are highly divergent, belonging to a lineage separate from that of the Old and New World arenaviruses. Furthermore, these viruses encode envelope glycoproteins that are more similar to those of filoviruses than to those of other arenaviruses. These findings implicate these viruses as candidate etiologic agents of IBD. The presence of arenaviruses outside mammals reveals that these viruses infect an unexpectedly broad range of species and represent a new reservoir of potential human pathogens.

Endogenous hepadnaviruses, bornaviruses and circoviruses in snakes

“…Our study only focused on non-retroviral EVEs because endogenous retroviruses (ERVs) have been extensively characterized in the genomes of many vertebrates [39] and various studies have shown that snake genomes, like all vertebrate genomes, harbour dozens or hundreds of ERVs [30,[40][41][42]. Our TBLASTX library did include the recently characterized snake arenaviruses, presumed to be the cause of inclusion body disease in various snake species [43], but no hits were recovered matching the genome of these viruses. All hits longer than 50 amino acids (aa) resulting from the TBLASTX search were then used as queries to perform a reciprocal BLASTP search of the GenBank non-redundant protein database (accessed in November 2013).…”

Doença do corpúsculo de inclusão e espondilite por Salmonella sp. em uma Boa constrictor constrictor

“…Doença do corpúsculo de inclusão (Inclusion body disease -IBD) é uma enfermidade que afeta serpentes, principalmente Pythonidae e Boidae (Schumacher et al 1994, Schumacher 2006, Chang & Jacobson 2010, Stenglein et al 2012, Hetzel et al 2013, Chang et al 2013, Turchetti et al 2013. Foi descrita pela primeira vez há quatro décadas e têm sido uma preocupação mundial devido à alta morbidade e mortalidade (Chang & Jacobson 2010, Stenglein et al 2012, Hetzel et al 2013, Chang et al 2013.…”

“…Foi descrita pela primeira vez há quatro décadas e têm sido uma preocupação mundial devido à alta morbidade e mortalidade (Chang & Jacobson 2010, Stenglein et al 2012, Hetzel et al 2013, Chang et al 2013. Entretanto, até o momento, só há um relato de caso de IBD no Brasil (Turchetti et al 2013).…”

“…A doença se caracteriza por corpúsculos intracitoplasmáticos em diversos tecidos (Schumacher et al 1994, Schumacher 2006, Chang & Jacobson 2010, Stenglein et al 2012, Chang et al 2013, Hetzel et al 2013, Turchetti et al 2013) e os sinais clínicos são consequência das inclusões no sistema nervoso central, levando a opistótono, desequilíbrio, paralisia flácida e inabilidade de voltar à posição quando colocados em decúbito dorsal (Chang & Jacobson 2010, Stenglein et al 2012, anisocoria e tremores da cabeça (Hetzel et al 2013). Além dos sinais neurológicos, sinais clínicos inespecíficos como anorexia, apatia (Hetzel et al 2013, Turchetti et al 2013) e regurgitação já foram associados à enfermidade (Schumacher et al 1994, Chang & Jacobson 2010, Stenglein et al 2012, Hetzel et al 2013, Turchetti et al 2013.…”

“…Além dos sinais neurológicos, sinais clínicos inespecíficos como anorexia, apatia (Hetzel et al 2013, Turchetti et al 2013) e regurgitação já foram associados à enfermidade (Schumacher et al 1994, Chang & Jacobson 2010, Stenglein et al 2012, Hetzel et al 2013, Turchetti et al 2013.…”