Screening, construction, and serological identification of the diagnostic antigen molecule EG-06283 for the diagnosis...

Several strategies exist to prevent and control echinococcosis, a global parasitic disease. However, most treatments are ineffective and adverse effects are common. Therefore, we aimed to screen protoscolex antigen molecules of Echinococcus granulosus to identify a diagnostic biomarker for hydatid disease. Published E. granulosus transcriptome sequencing data were analyzed to screen for antigen molecules that are highly expressed in protoscoleces but not in oncospheres. The membrane protein EG-06283 (annotated as Frizzled-4) was selected from 16 antigens, and its gene fragment was subjected to codon optimization and synthesis. rEG-06283 expression was induced in the pET-24a/EG-06283/BL21 strain; subsequently, the protein was purified and subcutaneously injected into ICR mice at weeks 0, 2, 4, and 6. Blood sampling occurred periodically to quantify serum immunoglobulin G (IgG) levels via enzyme-linked immunosorbent assays (ELISA). Immunogenicity was determined by western blot assays using sera from normal mice and mice with secondary hydatid infections. The antigen's immune reactivity and diagnostic value were validated using sera of patients with hydatid disease. ELISA results confirmed that the antigen molecule induced specific IgG production in mice, resulting in significantly higher levels than those in the adjuvant and control groups (P < 0.05). The western blot results indicated that the protein was recognized by antibodies in the sera of mice with hydatid infection and the antisera of immunized mice. Quantification of protein levels in the sera of patients with hydatid disease significantly differed from levels in healthy participants (P < 0.05). These results indicate that rEG-06283 is a potential diagnostic antigen for E. granulosus infections.