10. Male subjects who have not had a vasectomy and is sexually active with a woman of childbearing potential must agree to use an acceptable measure of birth control from 28 days prior to 1st vaccination until at least 60 days after the last vaccination. Acceptable methods of birth control include the following: - Abstinence (defined as refraining from heterosexual intercourse with a female partner of childbearing potential during participation in the study [from 28 days before the first vaccination until at least 60 days after the last vaccination]. -A double-barrier method of birth control, such as condom with spermicidal foam/gel/film/cream/suppository and partner with occlusive cap (diaphragm, cervical/vault caps). -In case the female partner is using an acceptable method of birth control (see Inclusion Criterion #8), a single-barrier method of birth control for the male subject is acceptable.