Pre-exposure to protects against subsequent lethal fungal infections.

Commensal fungi are an important part of human microbial community, among which and are two common opportunistic pathogens. Unlike the high pathogenicity of is reported to show low pathogenicity to the host. Here, by using a infection model, we were able to confirm the much lower virulence of than . Interestingly, pre-exposure to live (LCG) protects the larvae against subsequent various lethal fungal infections, including and . Inconsistently, heat-inactivated (HICG) pre-exposure can only protect against or re-infection, but not . Mechanistically, LCG or HICG pre-exposure enhanced the fungicidal activity of hemocytes against or . Meanwhile, LCG pre-exposure enhanced the humoral immunity by modulating the expression of fungal defending proteins in the cell-free hemolymph, which may contribute to the protection against . Together, this study suggests the important role of in enhancing host immunity, and demonstrates the great potential of model in studying the innate immune responses against infections.