The secretion of aspartyl proteinase, a virulence enzyme, by isolates of Candida albicans from the oral cavity of HIV-infected subjects

Abstract

Prevalence, serotype and in vitro secretion of aspartyl proteinase, a virulence enzyme, were studied in Candida isolates from the oral cavity of 337 HIV-infected subjects. Controls were 95 age-sex-matched HIV- (seronegative) subjects, belonging to either HIV-risk categories (47) or to the normal, general population (48). Fungi were isolated from 155 HIV+ subjects. C. albicans was the most prevalent species (85.8% of all isolates). 94.6% of C. albicans isolates were serotype A and all were agglutinated by a monoclonal antibody (AF1) directed against a major mannoprotein immunogen of the candidal cell wall, confirming previous results with C. albicans isolates from non-immunodeficient subjects. With regard to the stage of HIV infection, there were no statistically significant differences in the incidence of oral Candida carriage between asymptomatic (stage II) HIV+ and HIV- subjects, and between stage II and lymphadenopathic (stage III) individuals. Also, the low (3.8%) incidence of oral candidiasis in the subjects of the latter stage was insignificant with respect to stage II subjects. However, the incidence of C. albicans in stage IV (AIDS) subjects (46.8%) was significantly higher than in all other subjects, and in almost all cases, fungal isolation was accompanied by oral thrush and lower CD4+ lymphocyte counts (less than 400 x 10(6)/L). All isolates of C. albicans were proteolytic in vitro, as assessed by scoring the proteinase activity on BSA agar and monitoring the secreted proteinase antigen by a highly sensitive (1 ng) and specific immunoenzymatic assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Candida albicansSecreted Aspartyl Proteinases in Virulence and Pathogenesis

“…The higher level of proteinase activity correlated with the increased level of cell surface-associated and secreted Sap, as revealed by cytofluorometry and Western blotting, respectively. A similar study, but using fewer patients, reported a comparable increase in Sap activity in C. albicans strains isolated from the oral cavities of 44 HIV-positive patients (advanced disease) with oral candidiasis compared with that in 30 HIV-negative C. albicans carriers (46). However, since a control group of HIV-negative subjects with oral candidiasis was not included, it is unclear whether the observed increase in Sap production resulted from the advanced HIV status of the individuals or from the Candida infection.…”

“…Both Ollert et al (166) and De Bernardis et al (46) showed that the increase in Sap activity was observed only in patients with advanced HIV infection and not in those with earlier stages of HIV infection or HIV-negative subjects. This indicated that more virulent biotypes of C. albicans with heightened proteinase production might be selected in HIV-infected patients.…”

Carriage Frequency, Intensity of Carriage, and Strains of Oral Yeast Species Vary in the Progression to Oral Candidiasis in Human Immunodeficiency Virus-Positive Individuals

“…Felix and Wray also noted a higher rate of oral C. albicans carriage in HIV-positive subjects (93.1%) than in control subjects (57.4%) but did not examine the effect of CD4 ϩ lymphocytopenia (4). Similarly, DeBernardis et al noted that increased oral colonization correlated with clinical disease and low CD4 ϩ -cell counts but found that the rates of colonization were similar for asymptomatic HIV-positive patients and control subjects (about 30%) (3). In a more recent study, Fong et al also found a strong correlation between asymptomatic yeast carriage, development of thrush, and CD4 ϩ -cell counts (6).…”

Effects of Highly Active Antiretroviral Therapy on HIV-1-Associated Oral Complications

“…Secretion of a proteolytic enzyme aspartyl proteinase (SAP) is considered an important pathogenic attribute of this fungus [31]. C. albicans isolates from the oral cavities of HIV-1 seropositive individuals showed approximately an eight-fold increase in the constitutive expression of SAP compared with healthy individuals [32].…”