IDENTIFICATION AND PARTIAL-PURIFICATION OF A 26 KILODALTON ANTIGEN OFADULT HAEMONCHUS-CONTORTUS

Adult H. contortus soluble extracts were fractionated by means of gel filtration (S-200) and anion exchange chromatography (DEAE-Sephacel). Fractions from both analyses were checked by ELISA and western blottin g (WB) with sera from lambs infected with H. contortus, monospecific h eterologous sera (anti-Trichostrongylus colubriformis and anti-Telador sagia circumcinta) and sera from naturally infected sheep with mixed t richostrongylid infections, High cross reactivity was seen between H. contortus and heterologous sera, particularly with the anti-T. colubri formis serum, when fractions from gel filtration were checked by ELISA . Individual fractions containing the highest positive/negative and po sitive/heterologous ratios were pooled and analysed by SDS-PAGE, One o f the pools (A4) containing 2 regions around 48-55 and 25-27 kDa were strongly recognized by homologous sera in WE. Similar results were obt ained with the first peak eluted in the DEAE-Sephacel chromatography w ith NaCl 0.1 M. The pooled fraction A4 from gel filtration was further fractionated by anion exchange chromatography and the peak obtained w ith the NaCl gradient contained a ca. 26 kDa antigen apparently specif ic for the diagnosis of H. contortus infections in lambs.