Although the influence of PD-1 signal activity has been studied in several infection models, there are no data available concerning the role of this pathway in FH. To this end, we used the MHV-3induced mouse FH model to demonstrate that PD-1 signaling acts to limit the immunopathological damage during disease progression. Furthermore, our findings suggested that enhanced PD-1 signaling might represent a useful immunotherapeutic strategy for treating FH.