Improved Hepanostika, an enzyme-immunoassay for hepatitis B surface antigen.

Two modifications of Hepanostika were studied in order to improve this enzyme-immunoassay with regard to duration of the test, sensitivity and reading of test results. Test conditions and composition of some components of the test system were modified. With the first modification the test could be performed within 3 h and was about 3X as sensitive as Hepanostika. However, this method was less specific than Hepanostika and it was not suitable for routine screening. A second modification was studied with two differently prepared conjugates. The duration of the test was less than 4 h and the sensitivity was at least twice that of Hepanostika. The test results could be measured directly with a suitable photometer. Preliminary results with more than 500 deep-frozen donor sera showed that the specificity was acceptable with a number of false positives being less than 2%.