Detection of the circulating antigen 14-3-3 protein of Schistosoma japonicum by time-resolved fluoroimmunoassay in rabbits

The detection limit of 14-3-3-TRFIA was 0.78 ng/ml, with a linear measurement range from 0.78 to 800 ng/ml. The average intra-assay and inter-assay variability of this TRFIA was 8.9% and 12.2% respectively, and the mean recovery rate ranged from 92.1% to 115.5%. Within the first 21 days post-infection in rabbits, the positive rates of the 14-3-3-TRFIA were distinctly higher compared to ELISA. All these findings illustrate that 14-3-3-TRFIA has a higher detection efficacy and is a good early diagnostic method for active Schistosoma infection.A sandwich TRFIA for detecting the circulating antigen 14-3-3 of S. japonicum has been developed, and has demonstrated to be a good potential diagnostic method for schistosomiasis.Over the past 50 years, the ongoing national control program has made great progress in controlling schistosomiasis japonica in China, but this disease is still a major public health concern that afflicts millions of people in endemic areas [1,2]. Definite diagnosis of the disease plays a key role in the control of schistosomiasis [3]. Detection of Schistosoma circulating antigen is an effective approach to discriminate between previous exposure and current infection [3]. Effective chemotherapy and other interventions, such as local environment alternation [4], livestock in pens, and health education, have dramatically reduced schistosome infections, and major infection in endemic areas remains on a low level [5-7]. If the level of circulating antigen in host serum is less than the detection limit of a diagnostic method, false-negative results will be obtained, which would result in some patients missing treatment. Selecting an abundant circulating antigen as target would be very helpful for developing a highly sensitive diagnostic method of schistosomiasis. The signal transduction protein 14-3-3 of S. japonicum is abundant in excretory-secretary extracts [8], soluble egg extracts [9] and adult worm extracts [10], and can be used for the diagnosis of ac