Maternal immunization with RSV-VLPs in a non-human primate model of RSV infection

Using a non-human primate model, we evaluated an RSV pre-fusion F and G protein virus-like particle-based maternal immunization strategy and evaluated the effects of pregnancy on vaccine-induced immunity against RSV. Immunization during pregnancy induced robust systemic and mucosal IgG and neutralizing antibody titers. Upon post-partum challenge, this vaccination strategy enhanced humoral recall responses and Fc-effector functions, and reduced viral load in dams. Infants born to vaccinated dams had increased levels of RSV antibodies in the plasma and lung mucosa, which were correlated with reduced viral load; these infants also exhibited reduced pulmonary eosinophilia. Interestingly, vaccination during pregnancy was associated with increased post-fusion F responses and NAb titers, and we observed a reduction in viral load following post-partum challenge compared to nonpregnant controls. These results support the potential of a VLP-based maternal immunization strategy and provide insight into vaccine-induced immunity against RSV in pregnant and post-partum adults and infants.