Roles of Fc receptor gamma chain in inducing protective immune responses after F virus-like particles prime and FI-RSV boost against respiratory syncytial virus infection

Abstract The roles of Fc receptor (FcR) in protection or in inflammatory disease after RSV vaccination and infection remain unknown. Virus-like particles containing RSV fusion proteins (RSV F-VLPs) induce T-helper type 1 antibody responses and protection against RSV. Heterologous RSV F VLP prime and inactivated RSV (FI-RSV) boost vaccination was reported to be effective in providing protection without inflammatory disease. Here we investigated whether the FcRγ chain is important for immune protection by heterologous F VLP and FI-RSV vaccination using FcRγ chain knockout (−/−) mouse model. RSV F-VLP prime and FI-RSV boosted FcRγ−/− mice were not well protected, as shown by higher lung viral titers upon RSV virus challenge compared to RSV F-VLP prime-immunized wild-type mice. RSV F-VLP and FI-RSV immunization of FcRγ−/− mice induced significantly lower levels of neutralizing activity and interferon γ-producing CD8 T cells in bronchoalveolar lavage cells than those in in wild-type mice. In addition, FcRγ−/− mice displayed a trend of enhancing lung histopathology after RSV vaccination and infection. This study suggests that the FcR γ chain plays an important role in antiviral protection and CD8 T cell responses in RSV F-VLP and FI-RSV vaccination after RSV infections.