Bhalla, K.; Sanchez Leon-Hing, E.; Huang, Y.-H.; French, V.; Hu, G.; Wang, J.; Kretschmer, M.; Qu, X.; Moreira, R.; Foster, E. J.; Johnson, P.; Kronstad, J.

Cryptococcus neoformans, an invasive basidiomycete fungal pathogen, causes one of the most prevalent, life-threatening diseases in immunocompromised individuals and accounts for ~15% of AIDS-associated deaths. A dire need for the development of novel antifungal drugs, vaccines, and improved diagnostics has emerged with the increased frequency of fungal infections. Therefore, understanding the pathogenesis of C. neoformans and its interactions with the host immune system is critical for the development of therapeutics against cryptococcosis. Previous research demonstrated that C. neoformans cells lacking polyphosphate (polyP), an immunomodulatory polyanionic storage molecule, display altered cell surface architecture. However, the relevance of surface changes and the role of polyP in the virulence of C. neoformans remain unclear. Here we show that mutants lacking the polyphosphatases (Xpp1 and Epp1) are attenuated for virulence in a murine inhalational model of cryptococcosis, demonstrate reduced proliferation in host tissue, and provoke an altered immune response. An analysis of mutants lacking the polyphosphatases and the Vtc4 protein for polyP synthesis indicated that the Xpp1 and Epp1 contribute to the organization of the cell surface, virulence factor production, the response to stress, and mitochondrial function. Overall, we conclude that polyP mobilization plays a multifaceted role in the pathogenesis of C. neoformans.