Therapy of mucosal candidiasis by expression of an anti-idiotype in human commensal bacteria

Two recombinant strains of Streptococcus gordonii, secreting or displaying a microbicidal single-chain antibody (H6), and stably colonizing rat vagina , were used to treat an experimental vaginitis caused by Candida albicans. A post-challenge intravaginal delivery of the HG-secreting strain was as ef ficacious as fluconazole in rapidly abating the fungal burden. Three weeks after challenge, 75% and 37.5% of the rats treated with the He-secreting or displaying bacteria, respectively, were cured of the infection, which pers isted in 100% of the animals treated with a S. gordonii strain expressing a n irrelevant single-chain antibody. Thus, a human commensal bacterium can b e suitably engineered to locally release a therapeutic antibody fragment.