Diagnosis of opisthorchiasis by enzyme-linked immunosorbent assay using partially purified antigens.

Opisthorchis viverrini antigens were partially purified from adult worms collected from liver and extrahepatic biliary system of infected hamsters. Tegument fraction was obtained by chemical extraction, whereas other fractions were purified by Sephadex G-200 gel filtration chromatography. Five fractions of O. viverrini antigens were obtained, namely tegument extract, somatic extract, fraction 1 (P1), fraction 2 (P2) and fraction 3 (P3), respectively. The enzyme-linked immunosorbent assay technique was used to compare the reactivity of the five partially purified antigens. The sensitivity and specificity of all five antigens were compared by testing against the sera of 78 O. viverrini-infected individuals from O. viverrini endemic areas and 70 individuals from non-endemic areas infected with hookworm, Trichuris and Ascaris including 49 individuals with negative stool examination. The assays performed with tegument extract, somatic extract and P1 fraction were found to have 100% sensitivity, whereas the sensitivities of those with P2 and P3 were 96.1% and 83.3%, respectively. The tegument extract had the highest specificity as demonstrated by the lowest cross-reactivity with other parasites. Our results indicated that surface tegument is the most suitable antigen for use in immunological diagnosis of opisthorchiasis.

The absence of antagonism between extracts of Clinacanthus nutans Burm. and Naja naja siamensis venom.

Clinacanthus nutans Burm, a herb reputed in Thailand and Malaysia to be "snakebite antidote" has been tested in vitro and in vivo for antivenin activity. The aqueous extract of C. nutans leaves has been found to have no effect on the inhibition of neuromuscular transmission produced by purified Naja naja siamensis neurotoxin in isolated rat phrenic-nerve diaphragm preparations. The extract of C. nutans, when given orally or intraperitoneally, are ineffective in prolonging the survival time of experimental mice receiving lethal doses of N.n. siamensis crude venom. Oral administrations of the herb extracts pretreated with alpha-amylase or beta-amylase also fail to protect the animal. It is concluded that the extract of C. nutans can not antagonize the action of cobra venom.