Plasma IgG autoantibody against actin-related protein 3 in liver fluke Opisthorchis viverrini infection

Opisthorchiasis secondary to Opisthorchis viverrini infection leads to cholangiocellular carcinoma through chronic inflammation of the bile ducts and possibly inducing autoimmunity. It was hypothesized that plasma autoantibodies directed against self-proteins are biomarkers for opisthorchiasis. Plasma from patients with opisthorchiasis was tested using proteins derived from immortalized cholangiocyte cell lines, and spots reacting with plasma were excised and subjected to LC-MS/MS. Seven protein spots were recognized by IgG autoantibodies, and the highest matching scored protein was actin-related protein 3 (ARP3). The antibody against ARP3 was tested in plasma from 55 O. viverrini-infected patients, 24 patients with others endemic parasitic infections and 17 healthy controls using Western blot and ELISA. Immunoreactivity against recombinant ARP3 was significantly more prevalent in opisthorchiasis compared to healthy controls at Western blotting and ELISA (P < 0·05). Plasma ARP3 autoantibody titres were also higher in opisthorchiasis compared to healthy individuals (P < 0·01) and other parasitic infections including Strongyloides stercoralis (P < 0·001), echinostome (P < 0·05), hookworms (P < 0·001) and Taenia spp. (P < 0·05). It was further characterized in that the ARP3 autoantibody titre had a sensitivity of 78·18% and specificity of 100% for opisthorchiasis. In conclusion, it may be suggested that plasma anti-ARP3 might represent a new diagnostic antibody for opisthorchiasis.