Genomic architecture and evolutionary relationship of BA.2.75: A Centaurus subvariant of Omicron SARS-CoV-2

In this study, we explored the genomic architecture and phylogenomic relationship of BA.2.75, a subvariant of Omicron SARS-CoV-2. A set of 1468 whole-genome sequences of BA.2.75, submitted by 28 countries worldwide were retrieved from GISAID and used for finding genomic mutations. Moreover, the phylogenetic analysis of BA.2.75 was performed by using 2948 whole-genome sequences of all sub-variants of Omicron along with the Delta variant of SAS-CoV-2. We detected 1885 mutations, which were further grouped into 1025 missense mutations, 740 silent mutations, 72 mutations in non-coding regions, 16 in-frame deletions, 02 in-frame insertions, 8 frameshift deletions, 8 frameshift insertions and 14 stop-gained variants. Additionally, we also found 11 characteristic mutations having a prevalence of 81-99% and were not observed in any of the previously reported variant of SARS-CoV-2. Out of these mutations K147E, W152R, F157L, E210V, V213G, G339H were found in the NTD, and G446S & N460K in the RBD region of the Spike protein, whereas S403L and T11A were present in the NSP3, and E protein respectively. The phylogenetic relationship of this variant revealed that BA.2.75 is descended from the Omicron sub-variant BA.5. This evolutionary relationship suggests that the surge of BA.5 infections can reduce the severity of the infections accredited to BA.2.75. These findings would also improve our knowledge and understanding that how genetic similarities in different variants of SARS-CoV-2 can prime the immune system to fight off the infection caused by one subvariant, after defeating the other.