Fig. 1.

Schematic overview of the MHC-I antigen processing and presentation pathway in SARS-CoV-2 infection. Following SARS-CoV-2 infection rs2248374-A ERAP2 expressing cells produce wild type ERAP2 (ERAP2-wt) which can homodimerize or heterodimerize with ERAP1-wt (ERAP2-wt + ERAP2-wt; ERAP1-wt + ERAP2-wt), in order to process viral antigens to be presented on cell surface for recognition by specific CD8+ cytotoxic T lymphocyte (CTL) clones. Rs2248374-G ERAP2 expressing cells may also produce an alternative spliced isoform: ERAP2-ISO3. This variant, unlike ERAP2-wt, lack the catalytic domain but can still heterodimerize with both ERAP2-wt and ERAP1-wt. As a result, these unconventional heterodimers (ISO3 + ERAP2-wt; ISO3 + ERAP1-wt) may process viral antigens differently from the canonical ones, generating an alternative antigenic repertoire. This in turn may activate other CTL clones possibly triggering a more or less protective immune system response. ER: Endoplasmic reticulum; TAP: