# Respiratory syncytial virus mRNA vaccine-induced immunity and protection against subgroups A and B in mice

## TL;DR

A new mRNA vaccine called VER-027 protects mice against both subgroups of respiratory syncytial virus (RSV-A and RSV-B), showing strong immune responses and full protection.

## Contribution

The study introduces a novel mRNA vaccine encoding prefusion F proteins from both RSV-A and RSV-B, demonstrating dual-subgroup protection in mice.

## Key findings

- A two-dose regimen of VER-027 induced high IgG titers and potent neutralizing activity against RSV-A and RSV-B.
- The vaccine elicited robust CD8+ T cell responses specific to the F85-93 epitope.
- All vaccinated mice were fully protected against RSV-A and RSV-B challenge.

## Abstract

Respiratory syncytial virus (RSV) is a major global cause of severe lower respiratory tract infections in infants and older adults. RSV has 2 subgroups, A (RSV-A) and B (RSV-B), which circulate together with different patterns of dominance. A vaccine must protect against both. Reccently, prefusion F protein-based vaccines for maternal and older adult populations achieved ∼70% efficacy, and Moderna’s mRNA vaccine for older adults further underscores the potential of mRNA platforms. Here, we report preclinical evaluation of VER-027, a novel mRNA vaccine encoding prefusion F proteins from both RSV-A and RSV-B. A 2-dose intramuscular regimen induced high pre-F–specific immunoglobulin G (IgG) titers, potent neutralizing activity against both subgroups, and robust F85-93–specific CD8+ T cell responses. All mice vaccinated with this mRNA vaccine were fully protected against RSV-A and RSV-B challenge. These findings support VER-027 as a strong candidate for clinical development as a dual-subgroup RSV vaccine.