Discovery and comparative genomics of a novel enterovirus in camels

Abstract

In 2012, the Middle East Respiratory Syndrome Coronavirus was identified in the Middle East region, which contributes to severe respiratory diseases in humans. The virus was found from dromedary camels in the Middle East, an animal that the residents and travellers usually contact with. It promoted the interest to discover previously undescribed viruses in dromedary camels. Since the picornavirus is a common pathogen in animals and humans but there were few reports about picornavirus infection in dromedaries, we hypothesized that some previously unknown picornaviruses might exist in dromedaries. In the surveillance study for 215 fecal samples from dromedaries in Dubai, we discovered a novel dromedary camel enterovirus (DcEV) in four dromedary samples (one from adult camel and three from camel calves). The complete genome of DcEV was sequenced and analyzed. The genome size was 7426 bases excluding the polyadenylated tract and the open reading frame encoded 2168 amino acids. The phylogenetic result showed DcEV was clustered with members in the genus Enterovirusand was most closely related to representatives of the species Enterovirus F. DcEV and Enterovirus F shared the highes amino acid identities in the comparisons of DcEV and representatives of other species in the Enterovirus. DcEV also possessed a putative type 1 internal ribosome entry site element and gene and protein motifs similar to members of the Enterovirus. The G+C contents of DcEV were 45%, differing from those of Enterovirus F (50%) by 5%. The low Ka/Ks values of each coding gene suggested DcEV was stable evolving in dromedaries. In conclusion, DcEV belongs to the species Enterovirus in the family Picornaviridae and represents a novel species. The serological study in 172 serum samples from dromedaries in Dubai showed 52% of the dromedaries had been infected by DcEV. Further studies on the epidemiological and pathogenical features of DcEV are important to understand the novel picornavirus in this special group of animals.