Monitoring specific antibody responses against the hydrophilic domain of the 23 kDa membrane protein of Schistosoma japonicum for early detection of infection in sentinel mice

Development of IgM and IgG antibody levels against Sj23HD and SEA in S. japonicum infected mice was evaluated over the course of 42 days post-infection by enzyme-linked immunosorbent assay (ELISA) and immunoblotting. The Sj23HD and SEA specific IgM and IgG levels in mice all increased gradually over the course of infection, but IgM and IgG antibodies against Sj23HD presented earlier than those against SEA. Furthermore, the rates of positive antibody responses against Sj23HD were higher than those against SEA in the early stage of schistosome infection, suggesting that the likelihood of detecting early infection using anti-Sj23HD responses would be higher than that with anti-SEA responses. The use of immunoblotting could further improve the early detection of schistosome infection due to its greater sensitivity and specificity compared to ELISA. Additionally, the levels of Sj23HD and SEA specific antibodies positively correlated with the load of cercariae challenge and the duration of schistosome infection.This study demonstrated that antibody responses to the Sj23HD antigen could be monitored for early detection of schistosome infection in mice, especially by immunoblotting which demonstrated greater sensitivity and specificity than ELISA for detection Sj23HD antibodies.Schistosomiasis is an important tropical parasitic disease, with more than 200 million people currently infected among the 779 million people at risk of infection worldwide [1]. In the People's Republic of China (P.R. China), schistosome infection mainly occurs in the marshland and lake regions of Hunan, Hubei, Jiangxi, Anhui and Jiangsu provinces and in the hilly and mountainous regions of Sichuan and Yunnan provinces where the interruption of schistosomiasis transmission has been proven particularly difficult to achieve [2]. At present, approximately 65 million individuals are still at risk of infection in eastern Asia, including P.R. China [3,4], despite significant efforts to control the disease