IDENTIFICATION AND CDNA CLONING OF 2 NOVEL LOW-MOLECULAR-WEIGHT HOST-PROTECTIVE ANTIGENS FROM TAENIA-OVIS ONCOSPHERES

Identification and cDNA cloning of two novel low molecular weight host -protective antigens from Taenia ovis oncospheres. International Journ al for Parasitology 26: 195-204. Oncosphere antigens of Taenia ovis we re solubilised in sodium dodecyl sulphate and separated by electrophor esis in polyacrylamide gels (SDS-PAGE). Antigen-containing gel fractio ns cut from the region covering 18-12 kDa were shown to be highly immu nogenic in sheep challenge experiments. Specific antisera against 2 ca ndidate antigens at 18 and 16 kDa were used to screen a cDNA library p repared from T. ovis oncosphere mRNA. Recombinant proteins selected wi th antibody to the 16 and 18 kDa native antigens were expressed as GST fusion proteins. Vaccination trials using either of the 2 fusion prot eins To16.17-GST and To18-GST, revealed that each was capable of induc ing high levels of immunity in sheep against challenge infection with T. ovis eggs. Antibodies induced by vaccination with the recombinant a ntigens reacted specifically with their respective 18 or 16 kDa native oncosphere antigens. There was no apparent homology between the T. ov is cDNA coding for To18 and To16.17, or with another host-protective a ntigen, To45W, described previously. These additional host-protective antigens should prove a valuable adjunct to To45W and permit the devel opment of effective vaccination strategies.