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Intranasal booster with SARS-CoV-2 RBD protein fused to E. coli enterotoxin a subunit after primary mRNA vaccination

He-Chin Hsieh1, Chung-Chu Chen2, Wen-Chun Liu3

  • 1Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan.

Vaccine
|October 16, 2024
PubMed

Insights

An intranasal booster of RBD-LTA/RBD mixture proteins, following mRNA vaccination, sustains high antibody levels against SARS-CoV-2. This strategy offers a promising approach for achieving long-term immunity against COVID-19 and its variants.

Area of Science:

  • * Immunology
  • * Vaccinology
  • * Virology

Background:

  • * The COVID-19 pandemic, caused by SARS-CoV-2, necessitated the development of effective vaccines.
  • * Receptor binding domain (RBD)-based vaccines have shown promise, with various platforms and adjuvants explored.
  • * Previous work established RBD-LTA, a fusion protein, as an intranasal vaccine candidate.

Purpose of the Study:

  • * To evaluate the impact of an intranasal RBD-LTA/RBD mixture protein booster after mRNA vaccination.
  • * To assess the duration of antibody responses at 17 and 35 weeks post-vaccination.
  • * To determine the potential for long-term immunity against SARS-CoV-2 variants.

Main Methods:

  • * Intramuscular bivalent BA.4/5 mRNA vaccination was administered (one or two doses).
  • * An intranasal booster of RBD-LTA/RBD mixture proteins was given.
  • * Anti-RBD IgG and neutralizing antibody titers were measured over time.

Main Results:

  • * The intranasal booster maintained high levels of anti-RBD IgG and neutralizing antibodies.
  • * Antibody titers were comparable to those from a two-dose mRNA regimen.
  • * An additional booster significantly increased antibody titers, indicating sustained immune response.

Conclusions:

  • * Combining mRNA vaccination with an intranasal RBD-LTA/RBD mixture protein booster effectively sustains antibody levels.
  • * This approach shows potential for providing long-term protection against SARS-CoV-2 and its variants.
  • * Intranasal boosting offers a promising strategy for durable COVID-19 immunity.
Keywords:
Fusion proteinHeat-labile enterotoxin aIntranasal boosterReceptor binding domainmRNA immunization

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