Detection of salivary antibodies to crude antigens of Opisthorchis viverrini in opisthorchiasis and cholangiocarcinoma patients.

Opisthorchis viverrini (O. viverrini; known as human liver fluke) is a major health problem in the northeastern region of Thailand. Infection with O. viverrini is the cause of hepatobiliary disease and cholangiocarcinoma (CCA). Previous studies demonstrated specific antibodies to crude O. viverrini antigens in serum from O. viverrini-infected patients. However, no studies have measured specific antibodies to O. viverrini antigens in saliva from patients with opisthorchiasis and CCA. The objective of the study was to detect specific antibodies to crude O. viverrini antigens in saliva from patients with opisthorchiasis and CCA, and to evaluate their use for diagnosis of O. viverrini infection. Saliva samples from 23 control subjects, 30 opisthorchiasis patients, and 38 CCA patients were collected. ELISA was established for detection of salivary IgA and IgG to crude O. viverrini antigens. ANOVA was used to compare salivary IgA and IgG levels among groups. Salivary IgA to crude O. viverrini antigens in CCA patients was significantly higher than controls (p = 0.007). Salivary IgG in CCA patients was significantly higher than opisthorchiasis patients and controls (p = 0.010 and p < 0.001, respectively). The cut-off value from salivary IgG test demonstrated higher accuracy for positivity of O. viverrini infection than salivary IgA. In conclusion, specific antibodies to crude O. viverrini antigens were detected in saliva of patients with opisthorchiasis and CCA. Salivary antibodies reflect serum immune response to O. viverrini infection, and salivary IgG tends to be a good candidate for diagnosis of O. viverrini infection.