Neonatal mice immune response to COVID-19 mRNA vaccine

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• The COVID-19 pandemic saw the first licensing of mRNA vaccines for human use.
• Current mRNA vaccines for SARS-CoV-2 are not authorized for neonates, necessitating research into their safety and efficacy in this demographic.
• Limited data exists on the immunogenicity of SARS-CoV-2 mRNA vaccines in neonatal populations.

Purpose of the Study:

• To compare the immunogenicity of mRNA-encoded receptor binding domain (RBD) vaccines versus recombinant RBD protein vaccines in neonatal mice.
• To evaluate the antibody responses and functional capacity, specifically the inhibition of RBD binding to ACE2, induced by these two vaccine platforms in neonates.

Main Methods:

• Neonatal mice were immunized twice, three weeks apart, with either an mRNA-encoded RBD vaccine (RBD-mRNA-LNP) or a recombinant RBD protein vaccine (rRBD) adjuvanted with AddaVax™.
• Antibody levels, specifically IgG against RBD, were quantified.
• The functional capability of the induced antibodies was assessed by measuring the inhibition of RBD binding to the ACE2 receptor.

Main Results:

• Both vaccine platforms induced detectable anti-RBD antibodies in neonatal mice.
• The RBD-mRNA-LNP vaccine elicited significantly higher levels of IgG antibodies against RBD compared to the rRBD vaccine.
• Immunization with the RBD-mRNA-LNP vaccine resulted in more potent inhibition of RBD binding to ACE2.

Conclusions:

• The mRNA vaccine platform demonstrates superior immunogenicity in neonatal mice compared to the recombinant protein platform.
• mRNA vaccines elicit higher antibody titers and enhanced functional activity, including improved inhibition of viral binding, in neonatal models.
• These findings suggest the potential of mRNA vaccine technology for inducing robust immune responses in very young individuals, warranting further investigation.