Candidiasis--do we need to fight or to tolerate the Candida fungus?

Candidiases, infections caused by germination forms of the Candida fungus, represent a heterogeneous group of diseases from systemic infection, through mucocutaneous form, to vulvovaginal form. Although caused by one organism, each form is controlled by distinct host immune mechanisms. Phagocytosis by polymorphonuclears and macrophages is generally accepted as the host immune mechanism for Candida elimination. Phagocytes require proinflammatory cytokine stimulation which could be harmful and must be regulated during the course of infection by the activity of CD8+ and CD4+ T cells. In the vaginal tissue the phagocytes are inefficient and inflammation is generally an unwanted reaction because it could damage mucosal tissue and break the tolerance to common vagina antigens including the otherwise saprophyting Candida yeast. Recurrent form of vulvovaginal candidiasis is probably associated with breaking of such tolerance. Beside the phagocytosis, specific antibodies, complement, and mucosal epithelial cell comprise Candida eliminating immune mechanisms. They are regulated by CD4+ and CD8+ T cells which produce cytokines IL-12, IFN-gamma, IL-10, TGF-beta, etc. as the response to signals from dendritic cells specialized to sense actual Candida morphotypes. During the course of Candida infection proinflammatory signals (if initially necessary) are replaced successively by antiinflammatory signals. This balance is absolutely distinct during each candidiasis form and it is crucial to describe and understand the basic principles before designing new therapeutic and/or preventive approaches.

Comparison of protective effect of protein and DNA vaccines hsp90 in murine model of systemic candidiasis.

Preventive vaccination by a hsp90-expressing DNA vaccine and recombinant hsp90 protein vaccine, both derived from the Candida albicans hsp90 using BALB-c mouse model of systemic candidiasis, was performed. Hsp90 mRNA was cloned from a clinical isolate of C. albicans, converted to cDNA and cloned into vaccination plasmid pVAX1. Two methods of DNA application were tested: intramuscular (i.m.) and intradermal (i.d.) injection. Recombinant protein was applied by i.d. injection with Freund's adjuvant; the control groups received PBS or Freund's adjuvant only. Mice were vaccinated and after 19 d re-vaccinated. After 3 weeks, the mice were challenged with the live C. albicans in a dose of 5 x 10(6) CFU per mouse. After the challenge, the mice vaccinated i.d. with DNA vaccine survived for 39 and 64% longer compared to those receiving Freund's adjuvant and/or PBS, respectively. The i.m. application of the DNA vaccine did not provide any significant protectivity. The serum level of anti-candida-hsp90 serum IgG antibodies correlated with the survival rate in both i.d. protein and DNA vaccination approaches. We stressed the importance of specific humoral immunity in the mouse model of systemic candidiasis.

Isolation and characterization of an immunogenic fragment of heat shock protein 60 from Trichophyton mentagrophytes.

Heat shock protein 60 (hsp60) were isolated from several fungal, protozoal and many bacterial pathogens and successfully used for protective vaccination in some infection models. This work focuses on the isolation of recombinant hsp60 from the dermatophyte, Trichophyton mentagrophytes as a potentially protective antigen in trichophytosis. With the help of a previously tested set of degenerated primers, it was used reverse transcriptase polymerase chain reaction (RT-PCR) for isolation of partial cDNA of the hsp60 T. mentagrophytes (labelled hsp60-TM814), which was cloned into cloning vector. The sequencing of hsp60-TM814 cDNA and global alignment confirmed homology of the hsp60-TM814 with other members of the hsp60 family. Hsp60-TM814 cDNA corresponds to the region encoding the immunoprotective fragment of the hsp60 from Histoplasma capsulatum, used successfully in mouse model of histoplasmosis. A recombinant fragment (r-hsp60-TM664), 220 amino acids in length, was prepared in a prokaryote expression system, and its identity confirmed by mass spectroscopy. High immunogenicity of r-hsp60-TM664 was proven after subcutaneous immunization of mice. Immunized mouse sera recognized r-hsp60-TM664 on Western blots as well as hsp60 from mouse liver lysate and lysate of Candida albicans.