Alteration of Cryptosporidium parvum (Apicomplexa : Eucoccidiorida) oocystantigens following bleach treatment

Oocysts of the protozoan parasite Cryptosporidium parvum are passed in infe cted feces and subsequently ingested by susceptible hosts, thus perpetuatin g transmission of the infection in the natural environment. Detection of oo cysts is important to the water industry, especially in treatment plants us ing sanitizing and disinfecting chemicals. Commercial bleach containing sod ium hypochlorite is frequently used by researchers to decontaminate the sur face of oocysts prior to inoculating cell cultures. The present study analy zed oocyst protein patterns and antigen profiles before and after bleach tr eatment. Oocysts isolated from mouse feces were treated with a 20% bleach s olution at 4 degreesC for 30 min. Treated and non-treated oocysts were froz en, thawed, and sonicated to produce a C. parvum-oocyst homogenate (CPOH), which was subjected to gel electrophoresis and immunoblotting. Coomassie bl ue-stained electrophoretic gels revealed 33 and 15 protein bands front non- treated and treated CPOH, respectively. On Western blotting, 15 protein ban ds from non-treated CPOH were identified by polyclonal antibodies (hyperimm une mouse serum), but only 10 bands could be observed following bleach trea tment. Monoclonal antibodies (Mabs) 6B4 and 9D10, specific for epitopes on the intact oocyst wall, revealed different immunoblotting patterns before a nd after bleach treatment. Prior to treatment. Mall 6B4 reacted with 2 prot ein bands with molecular weights of 55 and 246 kD. while Mab 9D10 reacted w ith 2 bands with molecular weights of 168 and 230 kD. Following bleach trea tment, both the 55 and 246 kD bands (Mab 6B4) were still visible, but bands at 168 and 230 kD (Mab 9D10) were not. The utility of polyclonal and monoc lonal antibodies in detecting oocysts front different sources will depend u pon the chemical sensitivities of their target epitopes.