Time course of the antibody response in humans compared with rats experimentally infected with hepatic alveolar echinococcosis

Abstract

Human alveolar echinococcosis (AE) is caused by the accidental ingestion of Echinococcus multilocularis eggs. Early detection is essential as surgical resection is the only treatment for a complete cure. However, details are unclear about changes in the antibody response during the initial stages of infection, yet such information is useful for early serodiagnosis. Therefore, a long-term investigation was performed into the time course of the antibody response before 'positive' detection. Patient sera were used for enzyme-linked immunosorbent assay (ELISA) and Western blotting (WB) analysis using crude antigens extracted from E. multilocularis protoscoleces. Rats were experimentally infected with AE and similarly analysed by ELISA and WB. Among the markers for diagnoses, the 18kDa band (main marker) appeared last in the preoperative stages and disappeared first after operation in a WB test. Although the 18kDa antigen can be useful as a marker for AE diagnosis, it cannot contribute to the detection of some patients before the 18kDa band appearance. To avoid misdiagnosis, different diagnostic antigens such as the 26-28 and 7-8kDa bands should also be considered. These bands tend to appear earlier than the 18kDa band and thus offer the potential for early detection of AE. We first observed changes in the antibody response in a relatively early stage after infection in human AE cases. Notably, changes in the antibody response of two intermediate species were similar. These findings provide valuable information for the early detection of human AE cases in the future.