Fourth Dose of mRNA COVID-19 Vaccine Transiently Reactivates Spike-Specific Immunological Memory in People Living with HIV (PLWH)

Abstract

Background: People Living With HIV (PLWH), with advanced disease, lower CD4+ T cell counts or an unsuppressed HIV viral load can have a suboptimal vaccine response. For this reason, in the current COVID-19 pandemic, they represent a prioritized population for the SARS-CoV-2 fourth (or second booster) vaccine dose. This work aims to investigate the effects of a second booster on the reactivation of the spike-specific humoral and cell-mediated immune responses in PLWH. Methods: A total of eight PLWH, who received a fourth dose of the original mRNA vaccines were enrolled. They were evaluated before and then 7 days, 1 month and 2 months after the injection. The humoral response was assessed via a chemiluminescent immunoassay. Immunophenotyping and the functional evaluation of the SARS-CoV-2-specific cellular immune responses were performed via flow cytometry. Results: Anti-spike IgG levels were above the cut-off value for all subjects at all timepoints. The spike-specific CD4+ T cell response was reactivated one week after the fourth vaccine dose, and on average declined at two months post-vaccination. A similar trend was observed for the spike-specific B cells. A low percentage of spike-specific CD4+ T cells was activated by the B.1.1.529 BA.1 Omicron-spike mutated peptides, and the majority of these cells were reactive to the conserved portions of the spike protein. Similarly, the majority of the spike-specific memory B cells were able to bind both Wuhan and Omicron-spike entire protein. Conclusions: Spike-specific adaptive immune responses are transiently reactivated in PLWH following the fourth mRNA vaccine dose. The breadth of the immune responses to the mutated spike protein provides insight on the possible cross-reactivity for the SARS-CoV-2 variants of concern (VOCs).

Keywords: B cell response; HIV; Omicron; SARS-CoV-2; T cell response; fourth dose; humoral response; mRNA vaccine; people living with HIV.

Figure 1

Evaluation of the SARS-CoV-2-specific humoral response in eight people living with HIV (PLWH) up to 2 months after the fourth vaccine dose. Anti-S IgM (cut off = 1) (A), anti-S IgG (cut off = 87.8) (B), neutralizing IgG (cut off = 1) (C), and anti-RBD IgG (cut off = 130) (D) serum levels were evaluated in PLWH before, one week, one month and two months after the fourth vaccine dose. Each color corresponds to a different subject. Black dots indicate mean values. * p ≤ 0.05, ** p ≤ 0.005. Error bars indicate SE values.

Figure 2

Evaluation of the SARS-CoV-2-specific circulating CD4+ T and B cells in eight people living with HIV (PLWH), up to 2 months after the fourth vaccine dose. (A) Representative flow cytometric plots of the spike-specific CD154+CD4+IFN-γ+ T cells in one selected individual living with HIV. (B) Kinetic analysis of the frequencies of the CD154+CD4+ T cells producing at least one cytokine among IL-2, IFN-γ, and TNF-α in eight PLWH before, one week, one month, and two months after the fourth vaccine dose. Each color corresponds to a different subject. The T cell evaluation of subject V4 lacks the +7 days timepoint. Black dots indicate mean values. (C) Representative flow cytometric plots of the spike-specific B cells in one selected individual living with HIV. (D) Kinetic analysis of the frequencies of the spike-specific B cells in eight PLWH before, one week, one month, and two months after the fourth vaccine dose. Each color corresponds to a different subject. Black dots indicate mean values * p ≤ 0.05. Error bars indicate SE values.

Figure 3

Assessment of the CD4+ T and B cells responses specific to the Wuhan SARS-CoV-2 spike and the B 1.1.529 SARS-CoV-2 VOC spike, 2 months after the administration of the fourth vaccine dose in eight vaccinated PLWH vaccinated. (A) Visualization of the SARS-CoV-2 spike protein (1273 aa) covered by the S1, S+ and S peptide pools, the wild type sequence and the mutated sequence (aa 19–981) in the Omicron B1.1. 529 (BA.1). All peptide pools contain 15-mer peptides, 11 aa overlapping. (B) The frequencies of the CD154+ cells producing at least 1 cytokine among IL-2, IFN-γ and TNF-α, stimulated with the spike peptide pool, wild type (Wuhan) or the B. 1.1.529 (Omicron) peptide pool covering the mutated sequence of the spike. (C) Representative plots of the identification of the Wuhan spike-specific, labelled with APC-PB, and the Omicron spike-specific B cells, labelled with PE-PeVio770 within the Wuhan spike-specific pool. (D) Frequencies of the spike specific memory B cells binding both the Wuhan spike and Omicron spike and the B cells binding exclusively to the Wuhan spike. Each color corresponds to a different subject. Black lines indicate mean values.* p ≤ 0.05, ** p ≤ 0.005. Error bars indicate SE values.