[Immunoreactivity of the recombinant protein of Echinococcus granulosus antigen B]

To express the recombinant antigen B (rAgB) of Echinococcus granulosus (Eg) and investigate its immunoreactivity.

The rAgB gene fragments were inserted into pET41a (+) prokaryotic vector. The recombinant plasmid was transformed into E. coli BL21 (DE3) and followed by expression of the protein induced by isopropyl beta-D-1-thiogalactopyranoside (IPTG). The protein was purified with sepharose 4B by affinity chromatography, and tested by SDS-PAGE electrophoresis. Its immunoreactivity was examined by Western blotting, and a rapid diagnosis kit for human echinococcosis was used as control.

The constructed recombinant plasmid pET41a-rAgB was identified by PCR, digestion with restriction enzyme and sequencing. The recombinant rAgB-GST was about Mr 40 800 with a purity of 78.4%. Western blotting showed that the positive rate of rAgB-GST reacting with sera of cystic echinococcosis (CE), alveolar echinococcosis (AE), paragonimiasis westermani and clonorchiasis sinensis patients, and healthy persons is 79.2%(95/120), 51.1% (23/45), 0 (0/32), 0 (0/20), and 0 (0/24), respectively. Its overall sensitivity and specificity were 79.2% (95/120) and 81.0% (98/121), respectively, slightly higher than the sensitivity (72.8%, 75/103) and specificity (76.9%, 30/39) of the rapid diagnosis kit for human echinococcosis.

The rAgB-GST recombinant protein is recognized by the sera of CE and AE patients, showing a proper immunoreactivity.