[Evaluation of micro enzyme immunoassay technique (MEIA) for the demonstration of hepatitis B surface antigen]

The new Micro Particle Enzyme Immunoassay technique (MEIA, IMx HBsAg, Abbott) has been recently introduced for the detection of the presence of hepatitis B surface antigen (HBsAg). The present trial was carried out to determine the feasibility of using the IMx HBsAg with sera and plasma, and for comparison with RIA (Ausria II, Abbott) and RPHA (Reversecell, Megroken). Results obtained were as follows: In the test of 622 sera from inhabitants in Okinawa, 455 (73.1%) using IMx were positive for HBsAg, 454 (73.0%) with RIA, and 330 (53.0%) with RPHA. Five of the 179 tests using plasma from hemodialysis patients were positive for HBsAg with both IMx and RIA. One of these 5 was negative for HBsAg with RPHA. The difference of HBsAg positive rates between IMx and both RIA and RPHA increased with advancing age. Twenty four individuals were followed up from three to ten years and had had it confirmed that HBsAg had become negative in their sera, HBsAg was still positive from one to four years in both IMx and RIA after HBsAg became negative in RPHA. It was noted that HBsAg was assayed within one hour by IMx, and that the procedure was simple because of the autoanalyser equipped for this method. The results indicate that the sensitivity of IMx might be equal to that of RIA more than that of RPHA, and easier to measure than either of the others.