GENETIC-MODIFICATION OF A VAGINAL STRAIN OF LACTOBACILLUS-FERMENTUM AND ITS MAINTENANCE WITHIN THE REPRODUCTIVE-TRACT AFTER INTRAVAGINAL ADMINISTRATION

Many micro-organisms cause important diseases of the female genital tr act. Because systematic vaccination does not usually provide a good im mune response at mucosal sites, commensal lactobacilli from the female genital tract were developed as vehicles to deliver continued doses o f foreign antigen directly to the genital mucosal surface with the aim of stimulating strong local mucosal immune responses. Lactobacilli we re shown to be common inhabitants of the genital tract of the animal m odel studied, the guinea-pig. One species, Lactobacillus fermentum, wa s found in all guinea-pigs studied and was chosen for genetic manipula tion. Improved methods of electroporation were developed to enable the routine transformation of L. fermentum BR11 strain with the broad hos t range plasmid pNZ17. This recombinantly modified Lactobacillus strai n was shown to possess good segregational stability over 120 generatio ns in the absence of antibiotic selection. When this recombinant L. fe rmentum strain was administered to the vaginal tract of three guinea-p igs it persisted for only 5 days. Despite the relatively short period of persistence in these initial experiments, this novel vaccine approa ch could provide an effective means of stimulating mucosal immunity in the female genital tract.