Although coronaviruses are known to infect various animals by adapting to new hosts, interspecies transmission events are still poorly understood. During a surveillance study from 2005 to 2010, a novel alphacoronavirus, Bat. CoV HKU10, was detected in two very different bat species, Ro-Bat. CoV HKU10 in Leschenault's rousettes (Rousettus leschenaulti) (fruit bats in the suborder Megachiroptera) in Guangdong and Hi-Bat. CoV HKU10 in Pomona leaf-nosed bats (Hipposideros pomona) (insectivorous bats in the suborder Microchiroptera) in Hong Kong. Although infected bats appeared to be healthy, Pomona leaf-nosed bats carrying Hi-Bat. CoV HKU10 had lower body weights than uninfected bats. To investigate possible interspecies transmission between the two bat species, the complete genomes of two Ro-Bat. CoV HKU10 and six Hi-Bat. CoV HKU10 strains were sequenced. Genome and phylogenetic analyses showed that Ro-Bat. CoV HKU10 and Hi-Bat. CoV HKU10 represented a novel alphacoronavirus species, sharing highly similar genomes except in the genes encoding spike proteins, which had only 60.5% amino acid identities. Evolution of the spike protein was also rapid in Hi-Bat. CoV HKU10 strains from 2005 to 2006 but stabilized thereafter. Molecular- clock analysis dated the most recent common ancestor of all Bat. CoV HKU10 strains to 1959 (highest posterior density regions at 95% [HPDs], 1886 to 2002) and that of Hi-Bat. CoV HKU10 to 1986 (HPDs, 1956 to 2004). The data suggested recent interspecies transmission from Leschenault's rousettes to Pomona leaf-nosed bats in southern China. Notably, the rapid adaptive genetic change in Bat. CoV HKU10 spike protein by ~40% amino acid divergence after recent interspecies transmission was even greater than the~20% amino acid divergence between spike proteins of severe acute respiratory syndrome-related Rhinolophus bat coronavirus (SARSr-CoV) in bats and civets. This study provided the first evidence for interspecies transmission of coronavirus between bats of different suborders. © 2012, American Society for Microbiology.
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