SARS CoV-2 Delta variant structural proteins: Homology with opportunistic bacteria

The capacity of SARS CoV-2 for immune evasion can be considered universally recognized. Coronavirus and human protein homology may be one of the mechanisms of immune evasion. Delta variant necessarily has structural features that explain its specific qualities. The aim of our study is to find out whether mutations in the structural proteins of Delta variant change its homology with proteins present in the human body, i.e. human, bacterial and dietary. Using bioinformatics tools we detected homology on the heptamer level between Delta variant structural proteins and human proteins as well as some opportunistic bacteria proteins of the upper respiratory tract, lung and gut. Delta variant spike (S) and membrane (M) proteins have a large number of similarities (homologous correspondences) with the listed proteins, with the S:Δ156,157;R158G mutation having the greatest amount. The reason why SARS CoV-2 Delta variant has specific characteristics, most importantly increased lethality, is most likely to be found in a mutation at positions 156–158 of spike protein.