ABSTRACT
Background
Interindividual variations in vaccine-induced immunological responses are well-observed across different populations. This may underlie the highly polymorphic HLA molecules directly involved in antigen presentation to CD4+ T cells, leading to the generation of adaptive immunity. With the highest diversity among HLA molecules, HLA-DRB1 alleles and/or genotypes are often hypothesised to be associated with humoral and cellular immune components, as observed in other antiviral vaccines.
Objective
In this study, we aim to seek an association between HLA-DRB1 alleles and/or genotypes and plasma anti-SARS-CoV-2 (RBD) IgG levels.
Methods
Here, 98 participants who received two doses of COVID-19 vaccines were subjected to molecular typing of the HLA-DRB1 gene in association with the plasma anti-SARS-CoV-2 (RBD) IgG titre.
Results
The seropositive vaccinees had a mean (±SD) anti-SARS-CoV-2 IgG level of 302.89 (±105.64) IU/mL. The most commonly found allele was HLA-DRB1*15 (28.57%), while other alleles with frequencies above 5% were HLA-DRB1*07, HLA-DRB1*12, HLA-DRB1*10, HLA-DRB1*13, HLA-DRB1*04, and HLA-DRB1*03. The most frequent genotype was HLA-DRB1*07/15 (16.32%) among these participants. Other genotypes with frequencies above 5% were HLA-DRB1*10/15, HLA-DRB1*12/15, HLA-DRB1*07/12, HLA-DRB1*13/15, HLA-DRB1*03/15, HLA-DRB1*04/10, HLA-DRB1*07/10, and HLA-DRB1*07/13. The HLA-DRB1*15 allele was associated with anti-SARS-CoV-2 IgG levels among the high-antibody response (HAR) subset for whom more than 180 days (6 months) elapsed post-vaccination. However, no other alleles or genotypes were found to be directly associated with serological status or plasma anti-SARS-CoV-2 IgG levels among the study participants.
Conclusion
While this study provides insights into the genotypic and allelic distribution of the HLA-DRB1 gene among the Bangladeshi population, further investigation into allelic haplotypes, including other HLA (Class I and Class II) genes, is warranted to determine inter- and intra-population variability in vaccine-mediated protection against SARS-CoV-2.