Identification Of Similar Epitopes Between Severe Acute Respiratory Syndrome Coronavirus-2 And Bacillus Calmette-Guerin: Potential For Cross-Reactive Adaptive Immunity

Objectives. Bacillus Calmette-Guerin (BCG) vaccination has been implicated in protection against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and as a non-specific immunisation method against the virus. We therefore decided to investigate T-cell and B-cell epitopes within the BCG-Pasteur strain proteome for similarity to immunogenic peptides of SARS-CoV-2. Methods. We used NetMHC 4.0 and BepiPred 2.0 epitope prediction methods for the analysis of the BCG-Pasteur proteome to identify similar peptides to established and novel SARS-CoV-2 T-cell and B-cell epitopes. Results. We found 112 BCG MHC-I-restricted T-cell epitopes similar to MHC-I-restricted T-cell SARS-CoV-2 epitopes and 690 BCG B-cell epitopes similar to SARS-CoV-2 B-cell epitopes. The SARS-CoV-2 T-cell epitopes represented 16 SARS-CoV-2 proteins, and the SARS-CoV-2 B-cell epitopes represented 5 SARS-CoV-2 proteins, including the receptor binding domain of the spike glycoprotein. Conclusion. Altogether, our results provide a mechanistic basis for the potential cross-reactive adaptive immunity that may exist between the two microorganisms.