Echinococcus granulosus antigen B and seroreactivity in natural ovine hydatidosis

Hydatid cyst fluid from sheep and camels infected with Echinococcus granulosus, together with partially purified preparations of hydatid fluid antigen B and a recombinant antigen B product, were tested in an ELISA for their ability to detect IgG antibodies against E granulosus in the serum of naturally infected sheep. The antibody activity in sera from sheep naturally infected with Taenia hydatigena cysticercosis or Fasciola hepatica was also tested. All the antigen preparations from native hydatid cyst fluid were able to detect antibodies in the sera from a significant proportion of sheep with natural hydatid cyst infection, as identified by inspection at slaughter, although the seroreactivity was variable. The native antigen B preparation from camel hydatid cyst fluid gave the highest sensitivity in the ELISA (total 90 per cent), with 99 per cent specificity. In all cases, the recombinant antigen B was the least sensitive antigen (25 per cent) although it was highly specific (99 per cent).