ABSTRACT
Host genetic variability contributes to susceptibility to SARS-CoV-2 infection and COVID-19 evolution and the role of HLA system has not clearly emerged, suggesting the involvement of other factors. Studying response to vaccination with Spyke protein mRNA represents an ideal model to highlight whether the humoral or cellular responses are influenced by HLA. Four hundred and sixteen workers, vaccinated with Comirnaty beginning 2021, were selected within the Azienda Ospedaliera Universitaria "Città della Salute e della Scienza di Torino." The humoral response was determined with the LIAISON® kit, while the analysis of the cellular response was performed with the Quantiferon SARS-CoV-2 assay, for the S1 (receptor-binding domain; Ag1) and S1 and S2 (Ag2) subunits of the Spyke protein. Six HLA loci were typed by next-generation sequencing. Associations between HLA and vaccine response were performed with univariate and multivariate analyses. An association was found between A*03:01, B*40:02 and DPB1*06:01 and high antibody concentration and between A*24:02, B*08:01 and C*07:01 and low humoral responses. The haplotype HLA-A*01:01 ~ B1*08:01 ~ C*07:01 ~ DRB1*03:01 ~ DQB1*02:01 conferred an increased risk of low humoral response. Considering cellular responses, 50% of the vaccinated subjects responded against Ag1 and 59% against Ag2. Carriers of DRB1*15:01 displayed a higher cellular response both to Ag1 and Ag2 compared to the rest of the cohort. Similarly, DRB1*13:02 predisposed to a robust cellular response to Ag1 and Ag2, while DRB1*11:04 showed an opposite trend. Cellular and humoral responses to Comirnaty are influenced by HLA. Humoral response is mainly associated to class I alleles, with A*03:01, previously associated to protection against severe COVID-19, and response to vaccination, standing out. Cellular response predominantly involves class II alleles, with DRB1*15:01 and DPB1*13:01 prevailing. Affinity analysis for Spyke peptides is generally in line with the association results.
ABSTRACT
BACKGROUND: SARS-CoV-2 infection is heterogeneous in clinical presentation and disease evolution. To investigate whether immune response to the virus can be influenced by genetic factors, we compared HLA and AB0 frequencies in organ transplant recipients and waitlisted patients according to presence or absence of SARS-CoV-2 infection. METHODS: A retrospective analysis was performed on an Italian cohort composed by transplanted and waitlisted patients in a January 2002 to March 2020 time frame. Data from this cohort were merged with the Italian registry of COVID+ subjects, evaluating infection status of transplanted and waitlisted patients. A total of 56 304 cases were studied with the aim of comparing HLA and AB0 frequencies according to the presence (n = 265, COVID+) or absence (n = 56 039, COVID-) of SARS-CoV-2 infection. RESULTS: The cumulative incidence rate of COVID-19 was 0.112% in the Italian population and 0.462% in waitlisted/transplanted patients (OR = 4.2; 95% CI, 3.7-4.7; P < 0.0001). HLA-DRB1*08 was more frequent in COVID+ (9.7% and 5.2%: OR = 1.9, 95% CI, 1.2-3.1; P = 0.003; Pc = 0.036). In COVID+ patients, HLA-DRB1*08 was correlated to mortality (6.9% in living versus 17.5% in deceased: OR = 2.9, 95% CI, 1.15-7.21; P = 0.023). Peptide binding prediction analyses showed that these DRB1*08 alleles were unable to bind any of the viral peptides with high affinity. Finally, blood group A was more frequent in COVID+ (45.5%) than COVID- patients (39.0%; OR = 1.3; 95% CI, 1.02-1.66; P = 0.03). CONCLUSIONS: Although preliminary, these results suggest that HLA antigens may influence SARS-CoV-2 infection and clinical evolution of COVID-19 and confirm that blood group A individuals are at greater risk of infection, providing clues on the spread of the disease and indications about infection prognosis and vaccination strategies.