Antigenic Diversity among Oocysts of Clinical Isolates of Cryptosporidium parvum

Abstract

A panel of monoclonal antibodies has been produced against the protozoan parasite Cryptosporidium parvum which is a major cause of diarrhoeal disease in man and other animals. C. parvum oocysts from both a human and a bovine case of cryptosporidiosis were used as immunogens. A total of 11 different monoclonal antibodies were obtained which could bind to formalin-fixed oocysts. One was IgA but the remainder were all of IgM isotype. The reactivity of these monoclonal antibodies against a series of C. parvum oocysts obtained from 25 patients in Chile was examined using indirect immuno-fluorescence. Although a mixture of all of the 11 antibodies would have detected oocysts in each of the samples, no one monoclonal antibody recognised all oocysts. Each antibody showed a different recognition pattern. Thus by using these monoclonal antibodies we have demonstrated that there is tremendous antigenic variability among C. parvum oocysts. These antibodies should prove most useful in examining the epidemiology of C. parvum infections.