The purpose of this study is to determine whether CVD 1208S (a live, attenuated, oral vaccine) is safe and effective in the prevention of Shigella infection.

There are two purposes for conducting this Vaccine Study to evaluate an experimental vaccine called CVD 1208S (Center for Vaccine Development 1208S): 1) to learn whether CVD 1208S causes side effects, and 2) to learn whether the CVD 1208S gives people immunity to Shigella.

Inclusion Criteria:

• Age 18 to 45 years, inclusive.
• Good general health
• Expressed interest and availability to fulfill study requirements
• Informed, written consent.
• Agrees to indefinite storage of unused clinical specimens at the CVD for use in future research
• Agrees not to participate in another investigational vaccine or drug trial during the study
• Has no childbearing potential or agrees to abstain from becoming pregnant from the day of screening (at least 14 days before vaccination) until 6 weeks after the final vaccination by using birth control
• Agrees not to donate blood to a blood bank for 12 months after receiving the vaccine.

Exclusion Criteria:

• An acute or chronic medical condition that, in the opinion of the investigator, would render vaccination unsafe or would interfere with the evaluation of responses.

• Any current illness requiring daily medication (vitamins, birth control pills, nasal or topical medications, allowed);

• Blood in stool on >2 occasions (other than small amounts from straining) in past 12 months;

• Recurrent diarrhea (>5 episodes in past 6 months, each lasting 3 days or more).

• Immunosuppression

• Long term (greater than 2 weeks) use of oral or injected steroids, or high-dose inhaled steroids (>800 micrograms/day of beclomethasone dipropionate or equivalent) within the preceding 6 months (Nasal and topical steroids are allowed).

• History of abdominal surgery

• Medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 12 months.

• Known allergy or intolerance to ciprofloxacin, trimethoprim/sulfamethoxazole (or other sulfa antibiotic), ampicillin (for women) or corn.

• History of shigellosis or Shigella vaccination or challenge or a laboratory worker with known exposure to Shigella.

• Anticipates any of the following during the first 84 days (12 weeks) of the study (28 days, or 4 weeks for Cohort 1):

  • Shares a household with a child <3 years of age, a pregnant woman or a woman who plans to become pregnant during this time;
  • Household or sexual contact with someone who has weakened immunity (such as someone with HIV infection, someone receiving treatment for cancer, or an elderly person > 70 yrs);
  • Occupation as a food-handler, childcare (for children <3 years), or health care worker with direct patient contact.

• A clinically significant abnormality on physical examination

• Results of blood tests as defined by protocol

• Positive pregnancy test during medical screening or within 24 hours of inoculation or current breast feeding (women).

• Failure to attain a score of at least 70% on the written examination (two attempts permitted)

• During the past 3 years, developed diarrhea during travel to a developing country, or within 1 week of returning home.

• Receipt of any of the following:

  • Any vaccine or investigational drug within 30 days of study vaccine
  • A live, attenuated vaccine within 30 days of the study vaccine
  • A subunit or killed vaccine within 14 days of the study vaccine
  • A blood product in the 90 days before the study vaccine

• Receipt of antibiotics within 7 days of inoculation (or within 21 days if the antibiotic was azithromycin).

• Loose stools or any other acute illness such as fever >100.0 degrees F during the 48 hours before vaccination.