Serological differentiation between cystic and alveolar echinococcosis by use of recombinant larval antigens.

Two recombinant antigens of the larval stages of Echinococcus granulosus and Echinococcus multilocularis, termed EG55 and EM10, respectively, were applied for serodiagnosis and serological differentiation between parasitic infections caused by the metacestode tissue of both tapeworms. Antigen EM10 is synthesized by E. multilocularis larvae. Antigen EG55 represents the recombinant form of the low-molecular-weight subunit of antigen B, which is an Echinococcus genus-specific antigen. Both recombinant antigens were expressed as glutathione S-transferase fusion proteins. A sandwich enzyme-linked immunosorbent assay with monoclonal antibodies against EM10 and EG55 as capture reagents for the recombinant antigens was established and was evaluated with 74 serum samples from patients with histologically confirmed alveolar echinococcosis and 63 serum samples from patients with histologically confirmed cystic echinococcosis. A sensitivity of 93.2% and a specificity of 96.8% were achieved for the serodiagnosis of alveolar echinococcosis. Cystic echinococcosis could be detected with a sensitivity of 89.1% and a specificity of 98.6%.