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Updated: Nov 2, 2025
Analysis of Simian Immunodeficiency Virus-specific CD8+ T-cells in Rhesus Macaques by Peptide-MHC-I Tetramer Staining
Published on: December 23, 2016
SARS-CoV-2 vaccines elicit durable immune responses in infant rhesus macaques
Carolina Garrido1, Alan D Curtis2, Maria Dennis1
1Duke University Medical Center, Duke Human Vaccine Institute, Durham, NC, USA.
Insights
Two novel SARS-CoV-2 vaccines, mRNA-LNP and Protein+3M-052-SE, were safe and highly immunogenic in infant rhesus macaques. These findings support the development of pediatric COVID-19 vaccines to reduce transmission and disease impact.
Area of Science:
- Immunology
- Vaccinology
- Virology
Background:
- Pediatric SARS-CoV-2 infections pose risks, necessitating vaccines for infants.
- Age-related immune differences require careful evaluation of pediatric vaccines.
- Existing COVID-19 vaccines need age-specific safety and immunogenicity assessments.
Purpose of the Study:
- To assess the safety and immunogenicity of two novel SARS-CoV-2 vaccines in infant rhesus macaques.
- To provide proof-of-concept for a pediatric COVID-19 vaccine candidate.
- To evaluate the potential for durable immune responses and reduced SARS-CoV-2 transmission.
Main Methods:
- Infant rhesus macaques (n=16) received two intramuscular immunizations (weeks 0 and 4) with either mRNA-LNP or Protein+3M-052-SE vaccines.
- Assessed safety via adverse event monitoring.
- Evaluated immunogenicity through antibody binding (RBD, N-terminal domain, S1, S2), ACE2 blocking activity, neutralizing antibody titers, memory B cell responses, and T cell cytokine production (IL-17, IFN-γ, TNF-α).
Main Results:
- Both vaccines were well-tolerated with no adverse effects.
- High magnitude IgG binding, ACE2 blocking activity, and neutralizing antibody titers were observed, peaking at week 6.
- S-specific memory B cells and T cell responses (IL-17, IFN-γ, TNF-α) were detected and remained stable through week 22.
- mRNA-LNP vaccine responses were comparable to adult responses from the Moderna mRNA-1273 vaccine.
Conclusions:
- The S-2P mRNA-LNP and Protein+3M-052-SE vaccines are safe and highly immunogenic in infant rhesus macaques.
- These vaccines demonstrate potential for durable immunity in pediatric populations.
- Findings support the development of pediatric SARS-CoV-2 vaccines to mitigate COVID-19's health and socioeconomic impacts.
Abstract:
The inclusion of infants in the SARS-CoV-2 vaccine roll-out is important to prevent severe complications of pediatric SARS-CoV-2 infections and to limit transmission and could possibly be implemented via the global pediatric vaccine schedule. However, age-dependent differences in immune function require careful evaluation of novel vaccines in the pediatric population. Toward this goal, we assessed the safety and immunogenicity of two SARS-CoV-2 vaccines. Two groups of 8 infant rhesus macaques (RMs) were immunized intramuscularly at weeks 0 and 4 with stabilized prefusion SARS-CoV-2 S-2P spike (S) protein encoded by mRNA encapsulated in lipid nanoparticles (mRNA-LNP) or the purified S protein mixed with 3M-052, a synthetic TLR7/8 agonist in a squalene emulsion (Protein+3M-052-SE). Neither vaccine induced adverse effects. Both vaccines elicited high magnitude IgG binding to RBD, N terminus domain, S1, and S2, ACE2 blocking activity, and high neutralizing antibody titers, all peaking at week 6. S-specific memory B cells were detected by week 4 and S-specific T cell responses were dominated by the production of IL-17, IFN-γ, or TNF-α. Antibody and cellular responses were stable through week 22. The immune responses for the mRNA-LNP vaccine were of a similar magnitude to those elicited by the Moderna mRNA-1273 vaccine in adults. The S-2P mRNA-LNP and Protein-3M-052-SE vaccines were well-tolerated and highly immunogenic in infant RMs, providing proof-of concept for a pediatric SARS-CoV-2 vaccine with the potential for durable immunity that might decrease the transmission of SARS-CoV-2 and mitigate the ongoing health and socioeconomic impacts of COVID-19.
