Complete genome analysis of three novel picornaviruses from diverse bat species

Although bats are important reservoirs of diverse viruses that can cause human epidemics, little is known about the presence of picornaviruses in these flying mammals. Among 1,108 bats of 18 species studied, three novel picornaviruses (groups 1, 2, and 3) were identified from alimentary specimens of 12 bats from five species and four genera. Two complete genomes, each from the three picornaviruses, were sequenced. Phylogenetic analysis showed that they fell into three distinct clusters in the Picornaviridae family, with low homologies to known picornaviruses, especially in leader and 2A proteins. Moreover, group 1 and 2 viruses are more closely related to each other than to group 3 viruses, which exhibit genome features distinct from those of the former two virus groups. In particular, the group 3 virus genome contains the shortest leader protein within Picornaviridae, a putative type I internal ribosome entry site (IRES) in the 5'-untranslated region instead of the type IV IRES found in group 1 and 2 viruses, one instead of two GXCG motifs in 2A, an L→V substitution in the DDLXQ motif in 2C helicase, and a conserved GXH motif in 3C protease. Group 1 and 2 viruses are unique among picornaviruses in having AMH instead of the GXH motif in 3C(pro). These findings suggest that the three picornaviruses belong to two novel genera in the Picornaviridae family. This report describes the discovery and complete genome analysis of three picornaviruses in bats, and their presence in diverse bat genera/species suggests the ability to cross the species barrier.