B cell response after SARS-CoV-2 mRNA vaccination in people living with HIV

Abstract

Background: Limited longitudinal data are available on immune response to mRNA SARS-CoV-2 vaccination in people living with HIV (PLWHIV); therefore, new evidence on induction and persistence of spike-specific antibodies and B cells is needed.

Methods: In this pilot study we investigated the spike-specific humoral and B cell responses up to six months after vaccination with two doses of mRNA vaccines in 84 PLWHIV under antiretroviral therapy compared to 79 healthy controls (HCs).

Results: Spike-specific IgG persisted six months in PLWHIV with no significant differences compared to HCs, even though a significantly lower IgG response was observed in patients with CD4⁺ T cells < 350/mmc. The frequency of subjects with antibodies capable of inhibiting ACE2/RBD binding was comparable between PLWHIV and HCs a month after the second vaccine dose, then a higher drop was observed in PLWHIV. A comparable percentage of spike-specific memory B cells was observed at month six in PLWHIV and HCs. However, PLWHIV showed a higher frequency of spike-specific IgD^- CD27^- double-negative memory B cells and a significantly lower rate of IgD^- CD27⁺ Ig-switched memory B cells compared to HCs, suggesting a reduced functionality of the antigen-specific memory B population.

Conclusions: The mRNA vaccination against SARS-CoV-2 elicits humoral and B cell responses quantitatively similar between PLWHIV and HCs, but there are important differences in terms of antibody functionality and phenotypes of memory B cells, reinforcing the notion that tailored vaccination policies should be considered for these patients.

Fig. 1. Schematic representation of the study design.

PLWHIV (84 subjects) and healthy controls (HCs, 79 subjects) vaccinated with two doses of a SARS-CoV-2 mRNA vaccine (BNT162b2 Pfizer-BioNTech or mRNA-1273 Moderna) 3–4 weeks apart, respectively, were enrolled in the study. Blood samples were collected at pre v1 (day 0, baseline), pre v2, +30 v2 (1 month post second dose), +60 v2 (2 months post second dose), and +150 v2 (5 months post second dose). Plasma samples were tested for spike-specific IgG and ACE2/RBD binding inhibition while PBMCs were analyzed for spike-specific B-cell response.

Fig. 2. Spike-specific antibody response following SARS-CoV-2 mRNA vaccination.

a Anti-spike IgG detected at pre v1, pre v2, +30 v2, +60 v2, and +150 v2 in plasma of PLWHIV. Data are presented as box and whiskers diagram showing the minimum and maximum of all the data. Kruskal–Wallis test, followed by Dunn’s post test for multiple comparisons, was used for assessing statistical differences between groups. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001. b Time course of spike-specific IgG response in PLWHIV and HC. Antibody titers are expressed as the reciprocal of the dilution of sample reporting a double OD value compared to the background. Data are presented as geometric mean titers (GMT) with 95% CI. Mann–Whitney test was used for assessing statistical differences between groups at each time point. c, d Surrogate virus neutralization assay (sVN) performed at +60 v2 and +150 v2. In c, data are reported as ACE2/RBD binding inhibition percentage with box and whiskers diagram showing the minimum and maximum of all the data. A threshold (dotted red line) was placed at 30% inhibition percentage to discriminate between positive and negative samples. Kruskal–Wallis test, followed by Dunn’s post-test for multiple comparisons, was used for assessing statistical differences between groups. The percentage of positive subjects over all samples, tested at each time point, is reported in d. Fisher’s Exact Test was used to assessing statistical differences between groups. *P ≤ 0.05; **P ≤ 0.01. Sample size PLWHIV: pre v1 (n = 54), pre v2 (n = 38), +30 v2 (n = 53), +60 v2 (n = 51), +150 v2 (n = 22). Sample size HCs: pre v1 (n = 25), pre v2 (n = 50), +30 v2 (n = 52), +60 v2 (n = 75), +150 v2 (n = 69). All samples were biologically independent.

Fig. 3. Analysis of spike-specific memory B cells at 6 months after the beginning of the vaccination cycle (+150 v2).

a Gating strategy applied for identifying S⁺ RBD⁺ MBC in PLWHIV and HCs. b Percentages of S⁺ RBD⁺ cells identified within MBC pool in each group. c Contour plot analysis of CD27 vs. IgD within S⁺ RBD⁺ MBC, for identifying Ig-switched (IgD^-CD27⁺), Unswitched (IgD⁺CD27⁺) and double-negative (DN) (IgD^-CD27^-) MBC. The DN MBC were dissected according to CD11c and CD21 expression for the identification of DN1 (CD11c^-CD21⁺) and DN2 (CD11c⁺CD21^-) d-e Percentages of S⁺ RBD⁺ MBC subsets identified in c. Contour plot in a and c are representative from a single subject from each group. Statistical difference was assessed by Mann–Whitney test; *P ≤ 0.05. f t-SNE visualization of B cells and antigen-specific B cells in PLWHIV and HCs. t-SNE dimensionality reduction was used to visualize in a bidimensional space a multiparametric dataset. Major B-cell subsets (switched memory, swM; unswitched memory uswM; double negative, DN; and naive) from PLWHIV (left) and HCs (right) were displayed as contour plots in t-SNE map according to the expression of all analyzed markers. S⁺ RBD⁺ B cells were shown as black dots. Sample size b, f: PLWHIV (n  =  22), HCs (n  =  18). Sample size c-e: PLWHIV (n  =  10), HCs (n  =  13). All samples were biologically independent.