Abstract:

Objective To study the characteristics of spike（S） protein antigenic epitopes of severe acute respiratory syndrome coronavirus 2（SARS-CoV-2）,human coronavirus（HCoV）-OC43 and HCoV-HKU1. Methods The S protein sequences and spatial structures of SARS-CoV-2,HCoV-OC43 and HCoV-HKU1 were obtained from the National Center for Biotechnology Information（NCBI）. Multiple sequence alignment was used to analyze these protein sequences. Protean,IEDB and SYFPEITHI were used to predict epitopes. Results From the 65 complete SARS-CoV-2 S protein sequences included in NCBI,9 sequences of S proteins with no amino acid repeats were selected,and QHZ87592.1 was used as the standard sequence. The other 8 S protein sequences had 8 site mutations and 1 site deletion,but none of them were distributed in receptor binding domain（RBD）. RBD regions of S protein of SARS-CoV-2,HCoV-OC43 and HCoV-HKU1 were different. The amino acid sequences of the S2 subunits of the 3 coronavirus S proteins were highly similar. The B cell antigenic epitopes of S protein were mainly concentrated in S1 subunit,and there was no similarity among the 3 coronaviruses. The T cell antigenic epitopes of the S2 subunit of HCoV-HKU1 and HCoV-OC43 were all similar to that of SARS-CoV-2,and the highest similarity was 70.0%. Conclusions The T cell antigenic epitopes of the S2 subunit may be a common antigen of the 3 coronaviruses. Memory T lymphocytes sensitized by HCoV-OC43 and HCoV-HKU1 might play roles in heterosubtypic immunity to SARS-CoV-2 .

Key words: Severe acute respiratory syndrome coronavirus 2, Coronavirus, Heterosubtypic immunity