A novel dromedary camel enterovirus in the family Picornaviridae from dromedaries in the Middle East

The recent emergence of Middle East respiratory syndrome coronavirus from the Middle East and the discovery of the virus from dromedary camels have boosted interest in the search for novel viruses in dromedaries. Whilst picornaviruses are known to infect various animals, their existence in dromedaries was unknown. We describe the discovery of a novel picornavirus, dromedary camel enterovirus (DcEV), from dromedaries in Dubai. Among 215 dromedaries, DcEV was detected in faecal samples of four (1.9%) dromedaries [one (0.5%) adult dromedary and three (25%) dromedary calves] by reverse transcription PCR. Analysis of two DcEV genomes showed that DcEV was clustered with other species of the genus Enterovirus and was most closely related to and possessed highest amino acid identities to the species Enterovirus E and Enterovirus F found in cattle. The G+C content of DcEV was 45 mol%, which differed from that of Enterovirus E and Enterovirus F (49-50 mol%) by 4-5%. Similar to other members of the genus Enterovirus, the 59 UTR of DcEV possessed a putative type I internal ribosome entry site. The low ratios of the number of nonsynonymous substitutions per non-synonymous site to the number of synonymous substitutions per synonymous site (K_a/K_s) of various coding regions suggested that dromedaries are the natural reservoir in which DcEV has been stably evolving. These results suggest that DcEV is a novel species of the genus Enterovirus in the family Picornaviridae. Western blot analysis using recombinant DcEV VP1 polypeptide showed a high seroprevalence of 52% among serum samples from 172 dromedaries for IgG, concurring with its much higher infection rates in dromedary calves than in adults. Further studies are important to understand the pathogenicity, epidemiology and genetic evolution of DcEV in this unique group of animals.