Current research for a vaccine against Lassa hemorrhagic fever virus

Warner, Bryce M; Safronetz, David; Stein, Derek R

CD4 and CD8 T cells are activated early during LASV infection, and LASV-specific T cells are detected following convalescence despite a lack of LASV-specific antibodies. 13, 30 Strong T-cell responses against both NP and GPC of LASV seem to persist for years following infection. 25, 26 Indirect evidence from vaccination studies also suggests that T-cell immunity is important for protection against LF. Strong T-cell responses against GP1 and GP2 induced by a vacciniavectored LASV vaccine were protective against LASV challenge. 31 In addition, strong activation and proliferation of CD4 and CD8 T cells following LASV challenge are seen in animals that survive infection. In patients who have recovered from LF, LASV-specific antibody levels are present, but soon become undetectable while LASV-specific memory CD4 T cells persist. There is also evidence that seronegative survivors of LASV do not suffer from LF upon reinfection, likely due to a cell-mediated memory response. 26, 30, 32, 33 Overall, while the specific phenotypes of responding T cells and their roles in LASV infection remain to be seen, there is strong evidence suggesting that efficient activation and proliferation of LASV-specific T cells are important for protection against LF.