Molecular Advances in Severe Acute Respiratory Syndrome-associated Coronavirus (SARS-CoV)

Chow, Ken Yan Ching; Hon, Chung Chau; Hui, Raymond Kin Hi; Wong, Raymond Tsz Yeung; Yip, Chi Wai; Zeng, Fanya; Leung, Frederick Chi Ching

Recombination within certain types of viruses is a common phenomenon in various virus families (67 ), particularly for large RNA viruses, as a means of shedding the deleterious effects of the errors accumulated during its genome replication (68 ) . Recombination events within the coronavirus family (70 , 76 , 77 ) or with other non-related virus families (52 , 66 , 69 ) have been reported. Apparently, the diversity of the redundant accessory genes has been accompanied by extensive genome rearrangement by heterogeneous or homogenous RNA recombination events, providing useful information for the taxonomy of the coronaviruses. From this point of view, the SARS-CoV is definitely a new and unique member of the coronavirus family. The divergence of these redundant ORFs between the SARS-CoV and other known coronaviruses suggests that the SARS-CoV might have been circulating in other animal hosts long before its emergence, and somehow crossed into a human host several months ago either by a sudden bottleneck mutation event or a RNA recombination event with unknown sources.