Strong CD4+ T-Cell Responses to Ancestral and Variant Spike Proteins Are Established by NVX-CoV2373 Severe Acute Respiratory Syndrome Coronavirus 2 Primary Vaccination

Abstract Background NVX-CoV2373 is an efficacious coronavirus disease 2019 (COVID-19) vaccine comprising full-length recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (rS) glycoprotein and Matrix-M adjuvant. Phase 2 of a randomized, placebo-controlled, phase 1/2 trial in...

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Published inThe Journal of infectious diseases Vol. 228; no. 6; pp. 734 - 741
Main Authors Fries, Louis, Formica, Neil, Mallory, Raburn M, Zhou, Haixia, Plested, Joyce S, Kalkeri, Raj, Moldovan, Ioana, Patel, Nita, Albert, Gary, Robinson, Michelle, Cho, Iksung, Chau, Gordon, Dubovsky, Filip, Glenn, Gregory M
Format Journal Article
LanguageEnglish
Published Oxford Oxford University Press 15.09.2023
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Summary:Abstract Background NVX-CoV2373 is an efficacious coronavirus disease 2019 (COVID-19) vaccine comprising full-length recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (rS) glycoprotein and Matrix-M adjuvant. Phase 2 of a randomized, placebo-controlled, phase 1/2 trial in healthy adults (18–84 years of age) previously reported good safety/tolerability and robust humoral immunogenicity. Methods Participants were randomized to placebo or 1 or 2 doses of 5-µg or 25-µg rS with 50 µg Matrix-M adjuvant 21 days apart. CD4+ T-cell responses to SARS-CoV-2 intact S or pooled peptide stimulation (with ancestral or variant S sequences) were measured via enzyme-linked immunosorbent spot assay and intracellular cytokine staining. Results A clearly discernable spike antigen-specific CD4+ T-cell response was induced after 1 dose, but markedly enhanced after 2 doses. Counts and fold increases in cells producing Th1 cytokines exceeded those secreting Th2 cytokines, although both phenotypes were clearly present. Interferon-γ responses to rS were detected in 93.5% of 2-dose 5-µg recipients. A polyfunctional CD4+ T-cell response was cross-reactive and of equivalent magnitude to all tested variants, including Omicron BA.1/BA.5. Conclusions NVX-CoV2373 elicits a moderately Th1-biased CD4+ T-cell response that is cross-reactive with ancestral and variant S proteins after 2 doses. Clinical Trials Registration NCT04368988. Primary series of NVX-CoV2373 vaccine with Matrix-M adjuvant induces polyfunctional CD4+ T-cell responses of balanced to moderately Th1-biased phenotype. Essentially equivalent cytokine production by vaccinee cells can be stimulated by spike proteins of ancestral or multiple variant sequences.
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Potential conflicts of interest. L. F., R. R. M., H. Z., J. S. P., R. K., N. P., G. A., M. R., I. C., G. C., F. D., and G. M. G. are all salaried employees or contractors of Novavax. N. F. was a contractor for Novavax at the time this study was done, and is currently employed at Formative Health Pty Ltd, Casuarina NSW 2487, Australia. I. M. is an employee of Cellular Technology Ltd.
Present affiliation: Formative Health Pty Ltd, Casuarina, New South Wales, Australia.
Membership of the 2019nCoV-101 Study Group is provided in the Acknowledgments and in Supplementary Table 1.
All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
ISSN:0022-1899
1537-6613
DOI:10.1093/infdis/jiad163