Structural Perspective on Molecular Interaction of IgG and IgA with Spike and Envelope Proteins of SARS-CoV-2 and Its Implications to Non-Specific Immunity

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a ruthless killer of the human population and highly transmissible, has become a big threat to public health by spreading one of the most infectious coronavirus diseases (COVID-19). Vaccine production is of paramount importance at present, albeit it is a gradual and time taking process. Since the predicament demand is immediate prevention, we hypothesized the utility of IgG2a LA5 and IgA antibodies developed inside the body after vaccination to assess its protective effects as non-specific immunity against SARS-CoV-2. Identifying the vaccine for repurposing, we considered the C-terminal domain of spike protein (S1-CTD) and envelope (E) protein for molecular interactions with aforesaid antibodies using computational and Bioinformatics tools in order to elucidate its practicality and applicability. Our in silico findings exhibited the involvement of S1-CTD and E-protein hotspot residues as key players in molecular interaction with IgG2a LA5 and IgA and exhibited better binding efficiency (higher negative ∆G and lower Kd values) in comparison to their cognate host receptors (ACE2 and MPP5). Detailed hotspot residue analysis of S1-CTD and E-protein with IgG2a LA5 and IgA indicates that the existing vaccine could be used as a preventive measure against SARS-CoV-2.