Impact of SARS-CoV-2 vaccination on systemic immune responses in people living with HIV

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) and an ongoing global pandemic. Despite the development of vaccines, which protect healthy people from severe and life-threatening COVID-19, the immunological responses of people with secondary immunodeficiencies to SARS-CoV-2 mRNA vaccines are currently not well understood. Human Immunodeficiency Virus (HIV), causing acquired immunodeficiency syndrome (AIDS), targets CD4+ T helper (Th) cells that orchestrate the immune response. Anti-retroviral therapy suppresses HIV burden and restores Th cell numbers. Here, we investigated the humoral and cellular immune responses elicited by the BTN162b2 vaccine in a cohort of people living with HIV (PLWH), who receive anti-retroviral therapy. While antibody responses in PLWH increased progressively after the first and second vaccination compared to baseline, they were reduced compared to HIV negative study participants (controls). CD8+ T cells exhibited a general activated phenotype and increased effector and effector memory compartments. In contrast, CD4+ Th cell responses exhibited a vaccination-dependent increase and were comparable between PLWH and controls. In line with their reduced humoral response, the correlation between neutralizing antibodies and the CD4+ T cell response was decreased in PLWH compared to healthy controls. Interestingly, CD4+ T cell activation negatively correlated with the CD4 to CD8 ratio, indicating that low CD4 T cell numbers do not necessarily interfere with cellular immune responses. Taken together, our data demonstrate that COVID-19 mRNA vaccination in PLWH results in potent cellular immune responses, but the reduced antibody responses suggest that booster vaccination might be required for preventing disease.

The SARS-CoV-2 T-cell immunity is directed against the spike, membrane, and nucleocapsid protein and associated with COVID 19 severity

Identification of immunogenic targets of SARS-CoV-2 is crucial for monitoring of antiviral immunity and vaccine design. Currently, mainly anti-spike (S)-protein adaptive immunity is investigated. However, also the nucleocapsid (N)- and membrane (M)-proteins should be considered as diagnostic and prophylactic targets. The aim of our study was to explore and compare the immunogenicity of SARS-CoV-2 S-, M- and N-proteins in context of different COVID-19 manifestations. Analyzing a cohort of COVID-19 patients with moderate, severe, and critical disease severity, we show that overlapping peptide pools (OPP) of all three proteins can activate SARS-CoV-2-reactive T-cells with a stronger response of CD4+ compared to CD8+ T-cells. Although interindividual variations for the three proteins were observed, M-protein induced the highest frequencies of CD4+ T-cells, suggesting its relevance as diagnostic and vaccination target. Importantly, patients with critical COVID-19 demonstrated the strongest T-cell response, including the highest frequencies of cytokine-producing bi- and trifunctional T-cells, for all three proteins. Although the higher magnitude and superior functionality of SARS-CoV-2-reactive T-cells in critical patients can also be a result of a stronger immunogenicity provided by severe infection, it disproves the hypothesis of insufficient SARS-CoV-2-reactive immunity in critical COVID-19. To this end, activation of effector T-cells with differentiated memory phenotype found in our study could cause hyper-reactive response in critical cases leading to immunopathogenesis. Conclusively, since the S-, M-, and N-proteins induce T-cell responses with individual differences, all three proteins should be evaluated for diagnostics and therapeutic strategies to avoid underestimation of cellular immunity and to deepen our understanding of COVID-19 immunity.

A possible role of immunopathogenesis in COVID-19 progression

BackgroundThe role of cellular immunity in pathogenesis of COVID-19 is unclear and conflicting data points to insufficient or pathogenic immunity as drivers of COVID-19 progression. Here we aimed to delineate the phenotype and function of the immune system in patients with moderate, severe, and critical COVID-19. MethodsIn this prospective study, we included 53 patients with moderate (n=21), severe (n=18), and critical (n=14) COVID-19 manifestations. Using multiparametric flow cytometry we compared quantitative, phenotypic, and functional characteristics of circulating immune cells, SARS-CoV-2 antigen-reactive T-cells, and humoral immunity. ResultsDeep phenotypic profiling revealed a depletion of circulating bulk CD8+ T-cells, CD4+ and CD8+ T-cell subsets with activated memory/effector T-cells expressing CD57+, HLA-DR+, and the key activation and migration molecule CD11a++ in critical COVID-19. Importantly, survival from acute respiratory distress syndrome was accompanied by a recovery of the depleted CD11++ T-cell subsets including T-cells expressing CD28, CD57, HLA-DR activation/effector molecules. We further observed a stronger response of S-protein specific T-cells producing inflammatory cytokines in critical COVID-19 cases. This seemingly contradictory observation is in fact confirmation of the underlying immunopathogenesis in patients with critical COVID-19. ConclusionOur findings suggest a CD11a-based immune signature as a possible prognostic marker for disease development. Our data further reveal that increased rather than decreased SARS-CoV-2 specific T cell immunity is associated with adverse outcome in COVID-19. Tissue migration of activated effectors T-cells may constitute a crucial cornerstone in the immunopathogenesis of SARS-CoV-2 associated tissue injury. Trial registrationThis is a prospective observational study without a trial registration number. FundingThis work was supported by grants from Mercator Foundation, the BMBF e:KID (01ZX1612A), and BMBF NoChro (FKZ 13GW0338B). 25 Word summaryStronger S-protein reactivity and decreased frequency of activated memory/effector T-cells expressing CD11a++ suggests immunopathogenesis in critical COVID-19 mediated by tissue migration of activated effector T-cells.