[Evaluation of immunochromatography assay technique for detection of hepatitis B surface antigen].

A new immunochromatography assay technique (DAINASCREEN HBsAg, Dainabot) has been recently introduced for the detection of the presence of hepatitis B surface antigen (HBsAg). To evaluate the feasibility of using the DAINASCREEN HBsAg, we carried out comparison tests with this method and RPHA. Results obtained were as follows: In a test of 692 sera from inhabitants in Iki island, Nagasaki Prefecture, 24 (3.5%) were positive for HBsAg by both DAINA and RPHA. Twenty-four patients with hepatitis B were all positive in both methods. Thirty patients with autoimmune diseases and eight who had accidental needle exposure to the blood of patients with HBV infection were negative by both methods. Six individuals were followed over a period of 10 years and all eventually eliminated HBsAg from their sera. In four patients, HBsAg remained positive by DAINA at one yearly check after it had become negative by RPHA. In five patients, HBsAg remained positive by RIA and IMs after DAINA and RPHA had become negative. A good correlation was observed between DAINA and RPHA with a concordance rate of 99.5%. A good correlation of HBsAg titer between the two methods was observed and found to be significant (r = 0.87, p < 0.001). HBsAg assay was able to be completed within 15 minutes by DAINA and the procedure was simple. These results indicate that the sensitivity of DAINA is superior to RPHA and it is easy to use.