The discovery of a recombinant SARS2-like CoV strain provides insights into SARS and COVID-19 pandemics

Abstract

In December 2019, the world awoke to a new zoonotic strain of coronavirus named severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In the present study, we classified betacoronavirus subgroup B into the SARS-CoV-2, SARS-CoV and SARS-like CoV clusters, and the ORF8 genes of these three clusters into types 1, 2 and 3, respectively. One important result of our study is that the recently reported strain RmYN02 was identified as a recombinant SARS2-like CoV strain that belongs to the SARS-CoV-2 cluster, but has an ORF8 from a SARS-like CoV. This result provides substantial proof for long-existing hypotheses regarding the recombination and biological functions of ORF8. Based on the analysis of recombination events in the Spike gene, we propose that the Spike protein of SARS-CoV-2 may have more than one specific receptor for its function as gp120 of HIV has CD4 and CCR5. We concluded that the furin protease cleavage site acquired by SARS-CoV-2 may increase the efficiency of viral entry into cells, while the type 2 ORF8 acquired by SARS-CoV may increase its replication efficiency. These two most critical events provide the most likely explanation for SARS and COVID-2019 pandemics.