Identification of similar epitopes between severe acute respiratory syndrome coronavirus‐2 and Bacillus Calmette–Guérin: potential for cross‐reactive adaptive immunity

OBJECTIVES: Bacillus Calmette–Guérin (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.