THE ANTIBODY-RESPONSE TO 27-KDA, 17-KDA, AND 15-KDA CRYPTOSPORIDIUM ANTIGENS FOLLOWING EXPERIMENTAL-INFECTION IN HUMANS

Previous studies have suggested that persons infected with Cryptospori dium parvum develop antibody responses to 27-, 17-, and 15-kDa C, parv um antigens, Studies of volunteers infected with Cryptosporidium speci es provided an opportunity to evaluate the relationship between antibo dy reactivity to these antigens and infection outcome. As monitored by immunoblot, increases in specific antibody reactivity were more preva lent among volunteers who developed signs and symptoms of cryptosporid iosis (n = 11) than among asymptomatic infected (n = 7; P =.05) or ooc yst-negative volunteers (n = 11; P =.02), Volunteers with preexisting IgG antibody to the 27-kDa antigen excreted fewer oocysts than volunte ers without this antibody (P =.003), IgG reactivity to the 17-kDa anti gens and IgM reactivity to the 27-kDa antigens were higher at day 0 fo r asymptomatic infected persons than for those who developed symptoms (P =.03 and P =.04, respectively). These results suggest that characte ristic antibody responses develop following C, parvum infection and th at persons with preexisting antibodies may be less likely to develop i llness.