Molecular characterization of bat coronavirus HKU6

Abstract

Coronavirus belongs to subfamily Coronavirinae in the family of Coronaviridae. They can be further classified into 4 genera, Alphacoronavirus, Betacoronavirus, Gammmacoronavirus and Deltacoronavirus. In 2003, there was a large outbreak of Severe Acute Respiratory Syndrome (SARS) throughout the world. The fatality rate of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) was so high that triggered the surveillances on coronaviruses. Coronavirus can be detected in various species, including bats, birds, human, piglets and palm civets. Rhinolophus sinicus was identified as the reservoir of SARS-CoV which raised the interest in bat coronavirus. Various bats were found to be the carrier of coronavirus, including Myotis ricketti, Scotophilus sinicus, Rhinolophus sinicus and more. BatCoV HKU6 was firstly detected from Myotis ricketii in Hong Kong in 2006. In phylogenetic analysis of completed RNA-dependent RNA polymerase (RdRp) gene, BatCoV HKU6 clustered closely with Porcine epidemic diarrhea virus (PEDV) in same clade and classified into the lineage of Alphacoronavirus. In this study, the identification of susceptible cell line for BatCoV HKU6 was failed. This failure may probably due to the quality of the samples, absence of receptors and interference of host factors. The S1 sequence of BatCoV HKU6 spike proteins was completed in this study. In the phylogenetic analysis, S1 of BatCoV HKU6 was clustered closely with a special spike gene from a PEDV strain from Russia, PEDV/Belgorod/dom/2008. Moreover, S1 of PEDV/Belgorod/dom/2008 shares the highest sequence similarities to S1 of BatCoV HKU6. Therefore, we suggested a possible cross-species recombination event was occurred between bats and piglets.