ABSTRACT
While humoral immune responses to infection or vaccination with ancestral SARS-CoV-2 have been well-characterized, responses elicited by infection with variants are less understood. Here we characterized the repertoire, epitope specificity, and cross-reactivity of antibodies elicited by Beta and Gamma variant infection compared to ancestral virus. We developed a high-throughput approach to obtain single-cell immunoglobulin sequences and isolate monoclonal antibodies for functional assessment. Spike-, RBD- and NTD-specific antibodies elicited by Beta- or Gamma-infection exhibited a remarkably similar hierarchy of epitope immunodominance for RBD and convergent V gene usage when compared to ancestral virus infection. Additionally, similar public B cell clones were elicited regardless of infecting variant. These convergent responses may account for the broad cross-reactivity and continued efficacy of vaccines based on a single ancestral variant.
Subject(s)
Tumor Virus InfectionsABSTRACT
The progression of the COVID-19 pandemic leads to the emergence of variants of concern (VOC), which may compromise the efficacy of the currently administered vaccines. Antigenic drift can potentially bring about a reduced protective T cell immunity and consequently to more severe disease manifestations. To assess this possibility, the T cell responses to the wild-type, Wuhan-1 SARS-CoV-2 ancestral spike protein and Omicron B.1.1.529 spike protein were compared. Accordingly, peripheral blood mononuclear cells (PBMC) were collected from 8 healthy volunteers 4-5 months following a third vaccination with BNT162b2, and stimulated with overlapping peptide libraries representing the spike of either the ancestral or Omicron SARS-CoV-2 virus variants. Quantification of the specific T cells was carried out by a fluorescent ELISPOT assay, monitoring interferon-gamma (IFNg), interleukin-10 (IL-10) and interleukin-4 (IL-4) secreting cells. For all the examined individuals, comparable level of reactivity to both forms of spike protein were determined. In addition, a dominant Th1 response was observed, manifested mainly by IFNg secreting cells and only limited numbers of IL-10 and IL-4 secreting cells. The data demonstrates a stable T cell activity to the emerging Omicron variant in the tested individuals, therefore the protective immunity to the variant following BNT162b2 vaccination is not significantly affected.
Subject(s)
COVID-19ABSTRACT
The COVID-19 pandemic raises the need for diverse diagnostic approaches to rapidly detect different stages of viral infection. The flexible and quantitative nature of single-molecule imaging technology renders it optimal for development of new diagnostic tools. Here we present a proof-of-concept for a single-molecule based, enzyme-free assay for detection of SARS-CoV-2. The unified platform we developed allows direct detection of the viral genetic material from patients’ samples, as well as their immune response consisting of IgG and IgM antibodies. Thus, it establishes a platform for diagnostics of COVID-19, which could also be adjusted to diagnose additional pathogens.
Subject(s)
COVID-19ABSTRACT
Background: The immunogenicity and safety of the Pfizer-BioNTech BNT162b2 mRNA vaccine in people living with HIV-1 (PLWH) are unknown. We thus aimed to assess the immunogenicity and safety of this vaccine in PLWH.Methods: In this prospective open study, we enrolled 143 PLWH, aged ³18 years, who attended our clinic. Patients who had recovered from COVID-19 were excluded. SARS-CoV-2 receptor binding domain (RBD) IgG and neutralizing antibodies were measured and compared to those in a cohort of vaccinated health care workers (HCWs). Adverse events, viral load and CD4 cell counts were monitored.Findings: At a median of 15 (IQR 14-19) days following the first dose of the BNT162b2 vaccine and 18 (IQR 14-21) days after the second dose, anti-RBD IgG was positive in 66/128 (51%) and 139/141 (98%) PLWH, respectively. Among the HCWs, 235/399 (59%) and 269/272 (99%) developed anti-RBD IgG at a median of 14 (IQR 14-14) and 26 (IQR 24-27) days after first and second doses, respectively. Following the second dose, immune sera neutralized SARS-CoV-2 pseudo-virus (psSARS-2) in 97% and 98% of PLWH and HCW, respectively. Vaccination was associated with adverse events in 60% of PLWH, mainly pain at the injection site, fatigue, and headache. AIDS-related adverse events were not reported. HIV viral load increased in 3/143 (2%) patients from < 40 copies/mL to ≤ 100 copies/mL. CD4+ T cell count decreased from a geometric mean of 700 (95% CI 648–757) cells/mm3 to 633.8 (95% CI 588–683) cells/mm 3 (P<0.01). Interpretation: This study on BNT162b2 vaccination in PLWH revealed a high antibody response without detrimental effect on viral load. A small decline in CD4 cell count was noted, but it was not accompanied by clinical deterioration. This study thus provides support for the immunization of PLWH against COVID-19 with the BNT162b2 mRNA Covid-19 vaccine.Funding Statement: None.Declaration of Interests: None.Ethics Approval Statement: Written informed consent was obtained from all participants and the study protocol and informed consent were approved by the Institutional review board of Sheba Medical Center.