 - Female subjects who are, or who plan to become, pregnant during the study, or who are nursing a baby. Additionally, to be included in this study, a woman of child-bearing potential must have a negative urine pregnancy test at screening, during the run, and prior to viral inoculation and agree to use an effective method of birth control such as, but not limited to, birth control pills, contraceptive foam, diaphragm, intra uterine device IUD, abstinence, or condoms. 