Protective Immune Responses Against Systemic Candidiasis Evoked By DNA Vaccine Containing Epitope (LKVIRK)from HSP90of Candida, Albicans

Systemic candidiasis is an infection caused by a fungal pathogen Candida albicans (C. albicans). This is opportunistic, dimorphic yeast pathogens which are found existing commensally within the human host of a health individual and it is the most common fungal pathogen in human. The actual mechanism which triggers the invasion of host tissue still remains unclear as there is lack of substantial scientific evidence to explain this phenomenon. Over the past few decades, the incidence rate of systemic candidiasis has been propelled with a death rate of50%, especially among immunocompromised patients, and the most common nosocomial disease presently. The present antifungal drugs available have been proven to be very toxic and less effective, so therefore a more effective prophylactic treatment is urgently needed.The heat shock protein90(HSP90) of C.albicans has shown to confer protective response against candidiasis, including the specific epitope (LKVIRK) of candida albicans heat shock protein90and numerous experiments have been conducted in the past to prove the immunogenicity of the epitope LKVIRK.Our team successfully cloned epitope (LKVIRK) of C.albican HSP90into mammalian expression using pcDNA3.1as a vector forming DNA vaccine pD-HSP90C. ICR mice were vaccinated twice intramuscularly at two weeks interval by priming and boosting DNA vaccine pD-HSP90C. During vaccination electroporation technique was carried out. The serums were collected from the immunized mice two weeks after the second vaccination to detect the specific antibody titers and IL-2by ELISA and ELISAPOT respectively. More importantly, DNA vaccine pD-HSP90C protection against systemic C. albicans infection was evaluated, by challenged vaccinated mice with lethal dose of live C. albicans cells. Protection of DNA vaccine pD-HSP90C was determined in terms of Candida colony forming unites (CFU) per gram of tissue from kidneys of mice infected with live C. albicans cells. ELISA analysis from serum of mice shows that there was significant increase in specific antibodies level such as IgG, IgGl and IG2b compared to the control groups. In addition, both IL-2were also detected in the serum of immunized mice indicating that DNA vaccine pD-HSP90C can stimulate both Thl responses. Furthermore, kidney evaluation shows that there were fewer colony forming units (CFU) in kidneys of pD-HSP90C vaccinated mice compared to the control groups. Therefore, DNA vaccine pD-HSP90C can be considered as a potential vaccination component against systemic candidiasis.