Evaluation of 8-kDa subunits of antigen B from Echinococcus multilocularis for serodiagnosis of echinococcosis.

Antigen B (AgB) is a thermostable polymeric lipoprotein of 160 kDa and an important diagnostic antigen for serodiagnosis ot human cystic echinococcosis due to its promising sensitivity and specificity. Now it has been proven that this protein is encoded by a gene family. Our recent studies demonstrated the existence of homologues of these genes in E. multilocularis. Five different cDNAs and corresponding genomic DNA clones encoding homologues of EgAgB 8-kDa subunits were identified as EmAgB8/1, EmAgB8/2, EmAgB8/3, EmAgB8/4, and EmAgB8/5. These genes appeared to have been expressed in a developmentally regulated manner in the parasite life cycle. Our current work focused on serological evaluation of recombinant proteins of EmAgB 8-kDa subunits for the immunodiagnosis of human echinococcosis and dogs infected with Echinococcus. Western blot analysis indicated that rEmAgB8/1 is the most useful antigen for serodiagnosis of human cystic echinococcosis with highest sensitivity and specificity (81.1%) among the five subunits of EmAgB; rEmAgB8/3 can be used as a candidate antigen for establishment of coproantigen test for diagnosis of dogs infected with Echinococcus.