Identification of a particular antigen from a parasite cDNA library using antibodies affinity purified from selected portions of Western blots.

Portions of nitrocellulose filters containing blotted electrophoresed antigens of Schistosoma japonicum adult worms were reacted with polyclonal rabbit antisera raised to this human parasite. Eluted antibodies were used as probes for detection of antigen-positive clones in an Escherichia coli lambda gt11 amp3 expression library of adult worm cDNA. Several cloned antigens corresponding to a S. japonicum antigen of Mr 26 000, being sought as a candidate vaccine molecule in a mouse model of schistosomiasis japonica, were identified using this approach. The method provides an antibody reagent that is an attractive alternative to other more tedious means of producing oligospecific antibodies, including monoclonal antibodies, for screening of expression libraries.