Active and Passive Immunization of Pan-Fungal Vaccine NXT-2 Reduces Morbidity and Mortality in an Immunosuppressed Murine Model of Candida auris Systemic Infection.

BACKGROUND

Candida auris has emerged as a significant public health threat causing life-threatening systemic infections. Of particular concern is the frequency of multidrug resistance, high transmissibility, and persistence in the environment; thus, there is a need for novel strategies to prevent and treat this infection. We previously generated a "pan-fungal" vaccine candidate, NXT-2, which induces protective immunity against several invasive fungal infections.

METHODS

In this study, we investigated the efficacy of NXT-2 immunization against systemic C. auris infection in an immunosuppressed murine model and investigated the possible mechanisms by which NXT-2 protection is mediated in vitro.

RESULTS

Active immunization afforded significant improvement in survival and reduced morbidity in neutropenic mice challenged intravenously with C. auris compared to controls (48.4% vs. 13.8%). To assess humoral immunity in promoting protection, passive immunization with NXT-2-specific IgG to neutropenic mice prior to the challenge with C. auris resulted in significantly higher survival (42% vs. 0%) and low morbidity compared to controls. Sera from NXT-2-immunized animals inhibited biofilm formation and enhanced opsonophagocytic killing of multiple C. auris clades in vitro.

CONCLUSIONS

These findings show that immunization with NXT-2 improves survival in C. auris infection and that NXT-2 antibodies promote antifungal activity in vitro and in vivo. These results extend the range of the pan-fungal NXT-2 vaccine to include protection against systemic C. auris-mediated infection and provide a rationale for the development of NXT-2 monoclonal antibodies for the treatment of C. auris infections.