A Multivariant Surrogate Virus Neutralization Test Demonstrates Distinct SARS-CoV-2-Specific Antibody Responses in People Living with HIV after a Fourth Monovalent mRNA Vaccination or an Omicron Breakthrough Infection

Abstract

While neutralizing antibodies (nAbs) induced by monovalent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinations are primarily directed against the wildtype (WT), subsequent exposure to the Omicron variants may increase the breadth of the antibodies' cross-neutralizing activity. Here, we analyzed the impact of an Omicron breakthrough infection (BTI) or a fourth monovalent mRNA vaccination on nAb profiles in people living with human immunodeficiency virus (PLWH). Using a multivariant surrogate virus neutralization test (sVNT), we quantified nAbs in 36 three-times vaccinated PLWH, of whom 9 acquired a serologically confirmed Omicron BTI, 8 received a fourth vaccine dose, and 19 were neither infected nor additionally vaccinated. While nAbs against WT and Delta increased after the BTI and a fourth vaccination, a significant increase against BA.1, BA.2, and BA.5 was only observed after the BTI. However, there was no significant difference in nAb concentrations between the samples obtained after the BTI and fourth vaccination. In contrast, nAb levels were significantly lower in PLWH, who were neither infected nor additionally vaccinated after three vaccinations. Thus, our study demonstrates the suitability of a multivariant sVNT to assess hybrid humoral immunity after Omicron BTIs in PLWH vaccinated against SARS-CoV-2.

Keywords: Omicron; PLWH; SARS-CoV-2; antibodies; neutralization; surrogate; vaccination.

Figure 1

Baseline levels of binding inhibition between ACE and RBDs of different SARS-CoV-2 variants as assessed by the multivariant sVNT. The y-axis displays the levels of binding inhibition between angiotensin-converting enzyme 2 (ACE2) and the receptor-binding domains (RBD) of the SARS-CoV-2 wildtype, the Delta variant, and the Omicron subvariants BA.1, BA.2, and BA.5 in arbitrary units (calibrated to represent NT titers). These levels were compared among PLWH who were vaccinated three times with a monovalent mRNA vaccine, who subsequently acquired Omicron BTI, who received a fourth dose of the monovalent mRNA vaccine, and who were neither infected with SARS-CoV-2 nor vaccinated a fourth time. Comparisons were performed using the Wilcoxon matched pairs test (ns p ≥ 0.05). The cutoff for the sVNT was 10 arbitrary units for all variants, respectively. Abbreviations: BTI: breakthrough infection; ns: not significant.

Figure 2

Levels of binding inhibition between ACE2 and RBDs of different SARS-CoV-2 variants as assessed by the multivariant sVNT. The y-axis displays levels of the binding inhibition between angiotensin-converting enzyme 2 (ACE2) and the receptor-binding domains (RBDs) of the SARS-CoV-2 wildtype, the Delta variant, and the Omicron subvariants BA.1, BA.2, and BA.5 5 in arbitrary units (calibrated to represent NT titers). These levels were compared within PLWH who were vaccinated three times with a monovalent mRNA vaccine, who (A) subsequently acquired Omicron BTI, (B) received a fourth dose of the monovalent mRNA vaccine, and (C) were neither infected with SARS-CoV-2 nor vaccinated a fourth time. Comparisons were performed using the Wilcoxon matched pairs test (**** p < 0.0001, ** p < 0.01, * p < 0.05, ns p ≥ 0.05). The cutoff for the sVNT was 10 arbitrary units for all the variants, respectively. Abbreviations: BTI: breakthrough infection; ns: not significant, WT: wildtype.

Figure 3

Levels of binding inhibition between ACE and RBDs of different SARS-CoV-2 variants post-booster vaccination, post-BTI, and late during follow-up. The y-axis displays the binding inhibition between angiotensin-converting enzyme 2 (ACE2) and the receptor-binding domains (RBDs) of the SARS-CoV-2 wildtype, the Delta variant, and the Omicron subvariants BA.1, BA.2 and BA.5 in arbitrary units (calibrated to represent NT titers). The median level (columns) and individual levels (dots) of ACE2-RBD-binding inhibition are shown as assessed by the sVNT in the three-times vaccinated PLWH (monovalent mRNA vaccines) from (1) group A after they acquired breakthrough infection (BTI) with an Omicron variant (“post-Omicron BTI”), (2) group B after they received a fourth dose of the monovalent WT vaccine (“post-booster”), and (3) group C who were neither vaccinated a fourth time nor infected late after the third vaccination (“post-3rd vacc. late”). Comparisons were performed using the Kruskal–Wallis test and Dunn´s multiple comparison tests. The cutoff for the sVNT was 10 units for all variants respectively. Abbreviations: BTI: breakthrough infection; (*** p < 0.001, ** p < 0.01, * p < 0.05, ns p ≥ 0.05). Abbreviations: BTI: breakthrough infection; vacc.: vaccination; ns: not significant.