Correlation between D614G-mutated SARS-CoV-2 and CD4+/CD8+ T cells expression in Egyptian COVID-19 patients

Abstract Background Rapid pulmonary replication of SARS-CoV-2 can potentially trigger a strong immune response. In people with coronavirus disease 2019 (COVID-19) symptoms, cytokine storm syndrome often leads to acute respiratory distress syndrome and respiratory failure, which are key causes of mortality. Viral infections activate both the innate and adaptive immune systems, with cellular immune response particularly the role of T lymphocytes being crucial for actual antiviral defense beside COVID-19. Among the variants of SARS-CoV-2, the D614G mutation in the spike protein has become the furthermost widespread strain globally during the pandemic. This mutation is linked with increased infectivity and transmissibility and has been identified as the most frequent mutation reported in Egypt. Results The rate of CD8+ T cells was significantly increased ( P < 0.001) in ICU-admitted patients compared to both healthy people and patients with mild symptoms, while frequency of CD4+ T cells was significantly decreased ( P < 0.001) in ICU patients relative to the other groups. The CD4+/CD8+ ratio demonstrated 100% sensitivity and specificity for predicting disease severity. T cell immune responses subsequent infection with the D614G-mutated SARS-CoV-2 strain, showing an increase in CD8+ T cell frequency from day 6 to day 17 post-infection. Additionally, specific HLA-A alleles, including HLA-A24:02 and HLA-A02:01, were associated with the evaluation of specific peptides. Conclusion The CD4+/CD8+ ratio may serve as a valuable prognostic marker for disease severity in COVID-19 patients. Monitoring CD8+ T cell levels could help identify patients with mild symptoms who are at threat of requiring ICU admission. Furthermore, the SARS-CoV-2 D614G mutation is associated with an increased frequency of CD8+ T cells in Egyptian patients.