41 lactating Pakistani women were vaccinated orally with Salmonella typhi
vaccine alone or in combination with parenteral Vibrio cholerae whole cell
vaccine, in order to study the possible difference in the secretory response after live and
inactivated vaccines. The antibody response in saliva, milk and serum was recorded using the
enzyme-linked
immunosorbent assay, ELISA. All had prevaccination antibody levels against the 2
vaccines. The live S. typhi
vaccine gave a serum
IgG and
IgA response but did not influence the
IgM levels. Salivary or milk
secretory IgA (
SIgA) antibody levels showed both increases and decreases but in most cases remained unchanged. Even if the
vaccine was given in enteric coated capsules, the milk and salivary
SIgA response was more often decreased than increased, although somewhat higher serum
IgG levels were attained with this preparation. Parenteral
cholera vaccination enhanced both serum and
SIgA milk antibody response. Combination of the 2
vaccines did not have any untoward effect on the antibody response in serum or in secretions against V. cholerae or S. typhi LPS. The results show that an oral
vaccine often induces a rather poor, or even negative mucosal antibody response, while a parenteral
vaccine provokes a substantial
SIgA response in individuals orally primed by natural exposure. This is in agreement with our previous findings with oral and parenteral
poliovirus vaccines in this population.