Dual-antigen fusion protein vaccination induces protective immunity against Candida albicans infection in mice.

ABSTRACT

Candida albicans Is a leading cause of nosocomial bloodstream infections, particularly in immunocompromised patients. Current therapeutic strategies are insufficient, highlighting the need for effective vaccines. This study aimed to evaluate the efficacy of a dual-antigen fusion protein vaccine (AH) targeting the Als3 and Hyr1 proteins of C. albicans, using AlPO4 as an adjuvant. The AH vaccine was constructed by fusing Als317-432 and Hyr125-350 proteins, and its immunogenicity was tested in BALB/c mice and New Zealand white rabbits. Mice received three intramuscular doses of the vaccine combined with AlPO4, followed by a lethal challenge with C. albicans SC5314. Survival rates, antibody responses, cytokine production, fungal burdens, and organ pathology were assessed. The vaccine's efficacy was also validated using rabbit serum. Mice vaccinated with the AH-AlPO4 combination exhibited significantly higher antibody titers, particularly IgG and its subclasses, compared to controls (p < .001). The survival rate of vaccinated mice was 80% post-infection, significantly higher than the control group (p < .01). Vaccinated mice showed reduced fungal loads in the blood, kidneys, spleen, and liver (p < .05). Increased levels of interferon gamma and interleukin (IL)-17A were observed, indicating robust T helper (Th) 1 and Th17 cell responses. Vaccination mitigated organ damage, with kidney and liver pathology scores significantly lower than those of unvaccinated mice (p < .05). Rabbit serum with polyclonal antibodies demonstrated effective antifungal activity, confirming vaccine efficacy across species. The AH-AlPO4 vaccine effectively induced strong immune responses, reduced fungal burden, and protected against organ pathology in C. albicans infections. These findings support further development of dual-antigen vaccine strategies.

Candida, a fungus, is a major cause of bloodstream infections, especially in critical care settings. This study focused on developing a vaccine to protect against Candida infection. The vaccine targeted two key proteins, Als3p and Hyr1p, found on the surface of Candida, using a combination of these proteins. To create the vaccine, we used Als3p and Hyr1p to form a fusion protein called AH, and tested the vaccine on mice, administering it with different adjuvants (substances that enhance the immune response). The results showed that the AH vaccine, particularly when combined with the adjuvant AlPO4, induced a strong immune response in mice. This response included the production of specific antibodies and immune cells that are crucial for defending against Candida infections. Furthermore, mice receiving the AH-AlPO4 vaccine showed significantly better survival rates and lower levels of fungal infection compared to the control group or another experimental group. The vaccine also protected vital organs, such as the kidneys and liver, from Candida-induced damage. Additionally, we used rabbit serum to validate the efficacy of the vaccine, providing cross-species confirmation of its effectiveness. The study demonstrated the potential of the AH vaccine in eliciting robust immune responses and reducing the severity of Candida albicans infections. In summary, this research introduces a promising AH vaccine, which shows effectiveness in protecting against Candida infections. The study's innovative approach and positive results contribute to the ongoing efforts to develop vaccines against fungal infections, addressing a critical healthcare challenge. Further research is needed to explore the vaccine's long-term effectiveness and safety for potential use in clinical settings.