Volunteers will undergo several tests at their first visit to the clinic for this study. A blood sample (about 2/3 of an ounce) will be taken to test for HIV, hepatitis B and C, complete blood count, liver functions, blood chemistry and pregnancy in women of childbearing age. The blood sample will also be tested for antibodies to Vi, rEPA (the protein of the conjugate), and pectin. There will also be a urine collection for testing. If the laboratory tests are acceptable, volunteers will be asked to return to the clinic on a...