Immunoinformatics Study of SARS-CoV-2 Nucleocapsid Phosphoprotein Identifies Promising Epitopes with Mutational Implications.

The SARS-CoV-2 is rapidly evolving and new mutations are being reported from different parts of the world. In this study, we investigated the variations occurring in the nucleocapsid phosphoprotein (N-protein) of SARS-CoV-2 from India. We used several in silico prediction tools to characterise N-protein including IEDB webserver for B cell epitope prediction, Vaxijen 2.0 and AllergenFP v.1.0 for antigenicity and allergenicity prediction of epitopes, CLUSTAL Omega for mutation identification and PONDR webserver for disorder prediction, PROVEAN score for protein function and iMutantsuite for protein stability prediction. Our results show that 81 mutations have occurred in this protein among Indian SARS-CoV-2 isolates. Subsequently, we characterized the N-protein epitopes to identify seven most promising peptides. We mapped these mutations with seven N-protein epitopes to identify the loss of antigenicity in two of them, suggesting that the mutations occurring in the SARS-CoV-2 genome contribute to the alteration in the properties of epitopes. Altogether, our data strongly indicates that N-protein is gaining several mutations in its B cell epitope regions that might alter protein function.