ABSTRACT
Coronaviruses are a large group of enveloped viruses having positive sense Ribonucleic acid (RNA) as their genome. Coronaviruses belong to the order Nidovirales, whereby coronaviruses represent the major and largest group in Nidovirales under family Coronaviridae. Order Nidovirales comprises families Coronaviridae, Arteriviridae, Roniviridae and Mesoniviridae. Nidoviruses are enveloped, nonsegmented positive-strand RNA viruses that have certain distinctive characteristics Coronaviruses are principally placed and studied under the Coronavirinae subfamily; the other subfamily Torovirinae comprises genus Toroviruses which are known to cause infections in cattle, horses and swine, and Bafiniviruses which are known to cause infection in fishes. The coronavirus genome happens to be a nonsegmented, single-stranded and positive-sense RNA genome. Coronaviral infections are initiated when the virion binds to a specific cellular receptor of the host. Large-scale rearrangements of the S protein result in the entry of the virion into the host cell, which further leads to the fusion of viral and cellular membranes.
