RESUMEN
How human genetic variation contributes to vaccine immunogenicity and effectiveness is unclear, particularly in infants from Africa. We undertook genome-wide association analyses of eight vaccine antibody responses in 2,499 infants from three African countries and identified significant associations across the human leukocyte antigen (HLA) locus for five antigens spanning pertussis, diphtheria and hepatitis B vaccines. Using high-resolution HLA typing in 1,706 individuals from 11 African populations we constructed a continental imputation resource to fine-map signals of association across the class II HLA observing genetic variation explaining up to 10% of the observed variance in antibody responses. Using follicular helper T-cell assays, in silico binding, and immune cell eQTL datasets we find evidence of HLA-DRB1 expression correlating with serological response and inferred protection from pertussis following vaccination. This work improves our understanding of molecular mechanisms underlying HLA associations that should support vaccine design and development across Africa with wider global relevance. Teaser High-resolution typing of HLA diversity provides mechanistic insights into differential potency and inferred effectiveness of vaccines across Africa.
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Hepatitis BRESUMEN
Duration of protection from SARS-CoV-2 infection in people with HIV (PWH) following vaccination is unclear. In a sub-study of the phase 2/3 the COV002 trial (NCT04400838), 54 HIV positive male participants on antiretroviral therapy (undetectable viral loads, CD4+ T cells >350 cells/ul) received two doses of ChAdOx1 nCoV-19 (AZD1222) 4-6 weeks apart and were followed for 6 months. Responses to vaccination were determined by serology (IgG ELISA and MesoScale Discovery (MSD)), neutralisation, ACE-2 inhibition, gamma interferon ELISpot, activation-induced marker (AIM) assay and T cell proliferation. We show that 6 months after vaccination the majority of measurable immune responses were greater than pre-vaccination baseline, but with evidence of a decline in both humoral and cell mediated immunity. There was, however, no significant difference compared to a cohort of HIV-uninfected individuals vaccinated with the same regimen. Responses to the variants of concern were detectable, although were lower than wild type. Pre-existing cross-reactive T cell responses to SARS-CoV-2 spike were associated with greater post-vaccine immunity and correlated with prior exposure to beta coronaviruses. These data support the on-going policy to vaccinate PWH against SARS-CoV-2, and underpin the need for long-term monitoring of responses after vaccination.