Pilus vaccines.

Bacterial pili (fimbriae) are protein appendages which extend from the cell surface and serve to adhere the microorganism to body surfaces. These appendages have been isolated, purified and characterized as vaccine candidates. These vaccines stimulate an immune response which serves at least with regards to Neisseria gonorrhoeae to block the adherence of the microorganism to epithelial cells. Thus far, these vaccines have proven effective in some animal studies and in a limited number of human challenge studies. The problems that remain are: lack of broad cross reactivity of the vaccines thus far developed poor immunogenicity of the important binding ligands both in terms of quality and quantity of antibody produced and inadequate stimulation of antibody response at the local site of infection.