COVID-19: Attacks Immune Cells and Interferences With Antigen Presentation Through MHC-Like Decoy System

Abstract

The high mortality of coronavirus disease 2019 is related to poor antigen presentation and lymphopenia. Cytomegalovirus and the herpes family encode a series of major histocompatibility complex (MHC)-like molecules required for targeted immune responses to achieve immune escape. In this present study, domain search results showed that many proteins of the severe acute respiratory syndrome coronavirus 2 virus had MHC-like domains, which were similar to decoys for the human immune system. MHC-like structures could bind to MHC receptors of immune cells (such as CD4⁺ T-cell, CD8⁺ T-cell, and natural killer-cell), interfering with antigen presentation. Then the oxygen free radicals generated by E protein destroyed immune cells after MHC-like of S protein could bind to them. Mutations in the MHC-like region of the viral proteins such as S promoted weaker immune resistance and more robust transmission. S 127–194 were the primary reason for the robust transmission of delta variants. The S 144–162 regulated the formation of S trimer. The mutations of RdRP: G671S and N: D63G of delta variant caused high viral load. S 62–80 of alpha, beta, lambda variants were the important factor for fast-spreading. S 616–676 and 1014–1114 were causes of high mortality for gamma variants infections. These sites were in the MHC-like structure regions.