The recent outbreak of severe respiratory infections associated with a novel group C betacoronavirus (HCoV-EMC) from Saudi Arabia has drawn global attention to another highly probable "SARS-like" animal-to-human interspecies jumping event in coronavirus (CoV). The genome of HCoV-EMC is most closely related to Tylonycteris bat coronavirus HKU4 (Ty-Bat. CoV HKU4) and Pipistrellus bat coronavirus HKU5 (Pi-Bat. CoV HKU5) we discovered in 2006. Phylogenetically, HCoV-EMC is clustered with Ty-Bat. CoV HKU4/Pi-Bat. CoV HKU5 with high bootstrap supports, indicating that HCoV-EMC is a group C betaCoV. The major difference between HCoV-EMC and Ty-Bat. CoV HKU4/Pi-Bat. CoV HKU5 is in the region between S and E, where HCoV-EMC possesses five ORFs (NS3a-NS3e) instead of four, with low (31%-62%) amino acid identities to Ty-Bat. CoV HKU4/Pi-Bat. CoV HKU5. Comparison of the seven conserved replicase domains for species demarcation shows that HCoV-EMC is a novel CoV species. More intensive surveillance studies in bats and other animals may reveal the natural host of HCoV-EMC. © 2012 SSCC.
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