Candida albicans HWP1 gene expression and host antibody responses in colonization and disease

In vivo expression of the developmentally regulated Candida albicans hyphal wall protein 1 (HWP1) gene was analysed in human subjects who were culture positive for C. albicans and had oral symptoms (n = 40) or were asymptomatic (n = 29), or had vaginal symptoms (n = 40) or were asymptomatic (n = 29). HWP1 mRNA was present regardless of symptoms, implicating hyphal and possibly pseudohyphal forms in mucosal carriage as well as disease. As expected, in control subjects without oral symptoms (n = 10) and without vaginal symptoms (n = 10) who were culture negative in oral and vaginal samples, HWP1 mRNA was not detected. However, exposure to Hwp1 in healthy culture-negative controls, as well as in oral candidiasis and asymptomatic mucosal infections, was shown by the existence of local salivary and systemic adaptive antibody responses to Hwp1. The results are consistent with a role for Hwp1 in gastrointestinal colonization as well as in mucosal symptomatic and asymptomatic infections. Overall, Hwp1 and hyphal growth forms appear to be important factors in benign and invasive interactions of C. albicans with human hosts.