Introduction & Objective: Vacuolar proteinase is an aspartic enzyme in Candida albicans (C. albicans) that is expressed by VAP gene and plays an important role in the development of systemic candidiasis. The aim of this study was to evaluate VAP gene expression in C. albicans strains isolated from patients with systemic candidiasis.

Materials & Methods: The evaluation of VAP gene expression was performed using reverse transcriptase-polymerase chain reaction (RT-PCR) method and samples were electrophoresed in 1.5% agarose gels. In addition, a total of 48 female Balb/c mice (six-weeks old and weight of 25 g) were experimentally infected by various C. albicans strains and the level of VAP gene expression was assessed in yeasts obtained from the blood of infected mice.

Results: The level of VAP gene expression in non-Iranian strains was significantly higher than those of Iranian strains (P<0.05). Our results showed that VAP gene expression of C. albicans strains isolated from mice blood increased compared to human patients. A significant difference in the ratio of VAP to 18S rRNA genes was observed in both clinical and control strains of C. albicans isolated from non-Iranian patients compared to Iranian patients (P<0.05). The VAP and 18S rRNA bands were appeared after electrophoresis of the clinical strains of C. albicans obtained from human patients and mice blood that were about 220 and 302 bp, respectively.

Conclusion: VAP gene as producer proteinase can act as an important gene in the development of systemic candidiasis caused by C. albicans.