Nontoxic engineered virus nanofibers as an efficient agent for the prevention and detection of fungal infection

Candida albicans (C. albicans) infection has a high mortality rate in immunocompromised patients. Owing to the inefficiency of the current diagnostic system and the absence of licensed vaccines against candidiasis, the prevention of C. albicans infection remains a challenge. C. albicans infection can be evaluated and prevented by the anti-secreted aspartyl proteinase 2 antibody (anti-Sap2 IgG) and Hsp90 antibody (anti-Hsp90 IgG). In this study, to explore a new agent for the improvement of the diagnosis and the prevention of C. albicans infection, an engineered fd bacteriophage, which is considered a human-safe virus nanofiber, was designed and prepared with two epitopes that could induce and capture anti-Sap2 IgG and anti-Hsp90 IgG. The dual-display phage was employed as a novel capture probe to develop a new enzyme-linked immunosorbent assay (ELISA) method, which significantly improved the detection rate compared with those of the ELISA in which recombinant protein Sap2 was used as coating antigen to capture the specific antibodies (rSap2-ELISA) and the ELISA in which recombinant protein Hsp90 was used as coating antigen to capture the specific antibodies (rHsp90-ELISA). In addition, the nanofibers acted as a potential vaccine to immunize mice, as well as recombinant proteins, more efficiently mediated humoral and cellular immune responses, decreased levels of C. albicans colonization, and increased the survival rates in C. albicans-infected mice. Therefore, the phage dual-display nanofiber has been shown to be a powerful bifunctional agent for protection against and sensitive detection of clinical infections, which has the potential to be widely used in the life sciences, clinical medicine, and environmental sciences.