SARS-CoV-2 specific T-cell humoral response assessment after COVID-19 vaccination using a rapid direct real-time PCR amplification

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Abstract

Objectives

The SARS-CoV-2 immune response is mediated by both humoral and cellular immunity. In this study, SARS-CoV-2 specific cellular immunity was tested by a novel direct real-time PCR (dRT-PCR) assay, targeting mRNA of CXCL10, and compared with respect to an ELISA measuring interferon gamma (IFN-γ) release.

Methods

Whole blood (Li–He) and serum samples were collected from 92 healthcare workers (HCW), with three doses of homologous (Pfizer/BioNTech, n=74) or heterologous (Pfizer/BioNTech and Vaxzevria or Moderna, n=18) vaccinations. Li–He samples were incubated with SCV2 PANEL-1-T-ACTIVATION (Hyris srl, Lodi, Italy), or CoV-2 IGRA TUBE ELISA (Euroimmune, Lubeck, Germany). CXCL10 mRNA expression was analyzed by bCube/bApp (Hyris), while IFN-γ was evaluated by quant-T-Cell SARS-CoV-2 ELISA (Euroimmune). Anti-SARS-CoV-2 S-RBD IgG levels were measured in sera using a CLIA assay (Snibe, Shenzen, China).

Results

Imprecision of dRT-PCR assay was found to be satisfactory, and the two methods for measuring T cell immunity to SARS-CoV-2 peptides agreed in 82/87 (94.2%) of results. At qualitative dRT-PCR analyses, 81 subjects (93.2%) resulted as reactive to SARS-CoV-2 peptides, 3 (3.4%) were borderline and 3 were negative (3.4%). At univariate and multivariate analyses of quantitative dRT-PCR mRNA of CXCL10 and IFN-γ release results showed no difference between HCW with previous infection, homologous/heterologous vaccination, or demographical features. Anti-SARS-CoV-2 S-RBD IgG was associated with the previous infection and the time between the last vaccination or positivity.

Conclusions

Direct RT-PCR appeared accurate for determining the presence or absence of immunoreactivity of SARS-CoV-2 specific T cells, especially when rapid analyses are required, such as for organ transplantation.

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Most cited references 32

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Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine

Fernando P Polack, Stephen J. Thomas, Nicholas R.E. Kitchin … (2023)

Abstract Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the resulting coronavirus disease 2019 (Covid-19) have afflicted tens of millions of people in a worldwide pandemic. Safe and effective vaccines are needed urgently. Methods In an ongoing multinational, placebo-controlled, observer-blinded, pivotal efficacy trial, we randomly assigned persons 16 years of age or older in a 1:1 ratio to receive two doses, 21 days apart, of either placebo or the BNT162b2 vaccine candidate (30 μg per dose). BNT162b2 is a lipid nanoparticle–formulated, nucleoside-modified RNA vaccine that encodes a prefusion stabilized, membrane-anchored SARS-CoV-2 full-length spike protein. The primary end points were efficacy of the vaccine against laboratory-confirmed Covid-19 and safety. Results A total of 43,548 participants underwent randomization, of whom 43,448 received injections: 21,720 with BNT162b2 and 21,728 with placebo. There were 8 cases of Covid-19 with onset at least 7 days after the second dose among participants assigned to receive BNT162b2 and 162 cases among those assigned to placebo; BNT162b2 was 95% effective in preventing Covid-19 (95% credible interval, 90.3 to 97.6). Similar vaccine efficacy (generally 90 to 100%) was observed across subgroups defined by age, sex, race, ethnicity, baseline body-mass index, and the presence of coexisting conditions. Among 10 cases of severe Covid-19 with onset after the first dose, 9 occurred in placebo recipients and 1 in a BNT162b2 recipient. The safety profile of BNT162b2 was characterized by short-term, mild-to-moderate pain at the injection site, fatigue, and headache. The incidence of serious adverse events was low and was similar in the vaccine and placebo groups. Conclusions A two-dose regimen of BNT162b2 conferred 95% protection against Covid-19 in persons 16 years of age or older. Safety over a median of 2 months was similar to that of other viral vaccines. (Funded by BioNTech and Pfizer; ClinicalTrials.gov number, NCT04368728.)

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Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine

Lindsey Baden, Hana El Sahly, Brandon Essink … (2020)

Abstract Background Vaccines are needed to prevent coronavirus disease 2019 (Covid-19) and to protect persons who are at high risk for complications. The mRNA-1273 vaccine is a lipid nanoparticle–encapsulated mRNA-based vaccine that encodes the prefusion stabilized full-length spike protein of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes Covid-19. Methods This phase 3 randomized, observer-blinded, placebo-controlled trial was conducted at 99 centers across the United States. Persons at high risk for SARS-CoV-2 infection or its complications were randomly assigned in a 1:1 ratio to receive two intramuscular injections of mRNA-1273 (100 μg) or placebo 28 days apart. The primary end point was prevention of Covid-19 illness with onset at least 14 days after the second injection in participants who had not previously been infected with SARS-CoV-2. Results The trial enrolled 30,420 volunteers who were randomly assigned in a 1:1 ratio to receive either vaccine or placebo (15,210 participants in each group). More than 96% of participants received both injections, and 2.2% had evidence (serologic, virologic, or both) of SARS-CoV-2 infection at baseline. Symptomatic Covid-19 illness was confirmed in 185 participants in the placebo group (56.5 per 1000 person-years; 95% confidence interval [CI], 48.7 to 65.3) and in 11 participants in the mRNA-1273 group (3.3 per 1000 person-years; 95% CI, 1.7 to 6.0); vaccine efficacy was 94.1% (95% CI, 89.3 to 96.8%; P<0.001). Efficacy was similar across key secondary analyses, including assessment 14 days after the first dose, analyses that included participants who had evidence of SARS-CoV-2 infection at baseline, and analyses in participants 65 years of age or older. Severe Covid-19 occurred in 30 participants, with one fatality; all 30 were in the placebo group. Moderate, transient reactogenicity after vaccination occurred more frequently in the mRNA-1273 group. Serious adverse events were rare, and the incidence was similar in the two groups. Conclusions The mRNA-1273 vaccine showed 94.1% efficacy at preventing Covid-19 illness, including severe disease. Aside from transient local and systemic reactions, no safety concerns were identified. (Funded by the Biomedical Advanced Research and Development Authority and the National Institute of Allergy and Infectious Diseases; COVE ClinicalTrials.gov number, NCT04470427.)

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Targets of T cell responses to SARS-CoV-2 coronavirus in humans with COVID-19 disease and unexposed individuals

Alba Grifoni, Daniela Weiskopf, Sydney Ramirez … (2020)

Summary Understanding adaptive immunity to SARS-CoV-2 is important for vaccine development, interpreting coronavirus disease 2019 (COVID-19) pathogenesis, and calibration of pandemic control measures. Using HLA class I and II predicted peptide ‘megapools’, circulating SARS-CoV-2−specific CD8+ and CD4+ T cells were identified in ∼70% and 100% of COVID-19 convalescent patients, respectively. CD4+ T cell responses to spike, the main target of most vaccine efforts, were robust and correlated with the magnitude of the anti-SARS-CoV-2 IgG and IgA titers. The M, spike and N proteins each accounted for 11-27% of the total CD4+ response, with additional responses commonly targeting nsp3, nsp4, ORF3a and ORF8, among others. For CD8+ T cells, spike and M were recognized, with at least eight SARS-CoV-2 ORFs targeted. Importantly, we detected SARS-CoV-2−reactive CD4+ T cells in ∼40-60% of unexposed individuals, suggesting cross-reactive T cell recognition between circulating ‘common cold’ coronaviruses and SARS-CoV-2.