SENSITIVE RADIOIMMUNOASSAY FOR THE ANTI-VIRAL AGENT BW248U [9-(2-HYDROXYETHOXYMETHYL)GUANINE]

A sensitive radioimmunoassay (RIA) for the new antiviral agent, BW248U [9-(2-hydroxyethoxymethyl)guanine], has been developed. The antisera used in the assay were obtained by immunizing rabbits with a succinyl-BW248U-rabbit serum albumin conjugate. In the assay, a single tube per sample is employed throughout, succinyl-[3H]BW248U is used as the antigen, and only 0.1 ml of sample per tube is required. The procedure does not require sample extraction, and ammonium sulfate is used as the precipitating agent. The RIA has a useful range of 0.05 to 50 nmol of BW248U/ml and the concentrations of the drug determined by this method are in good agreement with those obtained by high-performance liquid chromatography. Naturally occurring purine bases and nucleosides, as well as a wide variety of nonrelated drugs, do not interfere with the assay. When antiserum from one rabbit was employed, the association constant with succinyl-[3H]BW248U was found to be 2.05 × 108 liters/mol while that for [3H]BW248U was 10-fold less. © 1979.