Journal of VirologicalMethods, 13 (1986) 245-253 Elsevier JVM 00493 245 A SENSITIVE SCREENING TEST FOR THE SIMULTANEOUS DETECTION OF HEPATITIS B SURFACE ANTIGEN AND ANTIBODY CAROL J. ATHERTON and ELIZABETH H. BOXALL Regional Virus Laboratory, East Birmingham Hospital, Bordesley Green, Birmingham, U.K. (Accepted 10 February 1986) A modification of the Blood Products Laboratory radioimmunoassay for hepatitis B surface antigen which allows simultaneous assay of both hepatitis B surface antigen and antibody is described. The sensitivity of the method has been assessed and its performance as a screening test in over 2,500 routine samples has been evaluated. HBsAg anti-HBs radioimmunoassay sensitive screening test INTRODUCTION The laboratory diagnosis of hepatitis B has become of increasing importance to the clinician. In our laboratory, this has resulted in a continual increase of work since we began screening for hepatitis B surface antigen (HBsAg) and antibody (anti-HBs) in 1970. Our screening methods have always included tests for both HBsAg and anti-HBs and have included complement fixation tests, immuno-electroosmophoresis (IEOP), Passive haemagglutination (PHA) and Passive haemagglutination inhibition (PHAI). These anti-HBs test systems are all sufficiently sensitive for finding high-titre sera for specific immunoglobulin production, but are not capable of detecting low levels of antibody such as are found in patients recovering from hepatitis B or in the early stages of a course of active immunisation. As a result many of our routine specimens require further testing by commercial radioimmunoassay (RIA) kits. The advent of vaccine has brought with it a need for an inexpensive, sensitive anti-HBs screening test to check vaccine response. These factors have prompted the development of a screening test for HBsAg and anti-HBs by RIA, which will provide greater sensitivity than our current PHA/PHAI system. The test system is a modification of the Blood Product Laboratory (BPL) RIA kit for HBsAg detection (Lane, 1981) which is a ‘solid-phase sandwich’ test. The modification which we describe allows the simultaneous assay of HBsAg and anti- 01660934/86/$03.50 0 1986 Elsevier Science Publishers B.V. (Biomedical Division)