Hepatitis B pre-S1 and pre-S2 proteins: clinical significance and relation to hepatitis B virus DNA.

Pre-S proteins may have an important role in virus assembly and virus entry into the host cell. The presence of pre-S proteins in serum has also been thought to correlate with active viral replication. To investigate whether pre-S proteins in serum might have additional diagnostic and/or predictive value for liver sequelae in HBV infection, sera from six different serological groups of patients with HBV markers (total number 363) and different manifestations of liver histology were examined for the presence of pre-S1 and pre-S2 proteins using micro-ELISAs. Pre-S1 and pre-S2 proteins were detected significantly more often in HBV-DNA-positive than in HBV-DNA-negative sera from HBsAg carriers. However, pre-S1 and pre-S2 proteins were also found in HBV-DNA-negative HBsAg carriers irrespective of serum HBeAg/anti-HBe or liver histologic findings. These results suggest that the presence of the pre-S1 and or pre-S2 proteins in serum either does not seem to reflect the presence of active viral replication and active liver disease or pre-S proteins are more readily detectable than HBeAg and HB-DNA as measured by a dot-blot technique. Furthermore, the presence of pre-S proteins in serum is strongly correlated with that of HBsAg.

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%.

Enzyme-linked immunosorbent assay for hepatitis B surface antigen.

A solid-phase enzyme-linked immunosorbent assay (ELISA), based on the "sandwich" principle with use of microtiter plates, was developed for the detection of hepatitis B surface antigen (HBSAg). Results could be read within one day by the naked eye or by colorimeter. The detection level was less than or equal to 5-10 ng of HBSAg/ml. The sensitivities of ELISA and radioimmunoassay were about the same in dilution series and in a follow-up study of 19 patients with acute hepatitis B infection. In 11 European medical centers where greater than 50,000 samples were tested, ELISA detected significantly more HBSAg-positive samples than a reversed hemagglutinatiom test. No significant difference in sensitivity between ELISA and radioimmunoassay could be demonstrated. On the average, 2.2% of readings were false-positive reactions. Falsely positive samples were identified by a confirmatory test.