Dynamic study of HBsAg and HBeAg in saliva samples from patients with hepatitis B infection: diagnostic and epidemiological significance.

Analysis of 505 cases history of patients among men with viral hepatitis demonstrates that HBV infected patients represent 68.9% of the total and that a non-parenteral rate of transmission is the most likely means of hepatitis B infection. Saliva and serum testing for the presence of specific HBV markers (HBsAg, HBeAg and HBV DNA) at different phases of the infection process were carried out to review the diagnostic and epidemiological value of saliva samples from patients with acute viral hepatitis B. The frequency of HBsAg detection by Enzyme Immune Assay (EIA) in saliva of patients in acute period was found to correlate with the frequency of its detection in serum. In early convalescence the frequency of detection of that antigen in serum (59.5% of patients) was significantly higher than in saliva (23.8%) (P < 0.001). The frequencies of HBeAg detection by EIA in saliva samples was significantly higher than that in serum samples in both acute phase (84.3% and 28.1% of patients, respectively) and in early convalescence (56.2% and 3.1% of patients, respectively). The study of frequencies of detection of these antigens in the dynamics of the disease up to the total recovery of patients (observations were carried out for the period of 60 days and longer) showed that in most patients there was a faster disappearance HBsAg from saliva than from serum. By the end of second month this antigen was detected in saliva of only 8.3% of patients whereas in serum in the same period HBsAg was detected in 33.3% of patients. HBeAg became undetectable in blood whereas HBs-antigenemia was still pronounced, and a month after the beginning of the disease it was not found in serum specimens. In saliva, HBeAg was detected in 95.8% of patients observed directly after admission. A month after the beginning of the disease it was detected in saliva of 66.7% of patients and, by the end of observation period, in 12.5% of patients recovered from viral hepatitis. HBV DNA revealed by PCR in saliva and serum of HBV-infected patients was detected in acute period not only in serum (84.6% of cases) but also in saliva (46.2% of cases). The data illustrate the diagnostic value of saliva and point to the possible role of saliva as a source of HBV infection.

Site-directed mutagenesis of the tick-borne encephalitis virus NS3 gene reveals the putative serine protease domain of the NS3 protein.

Several mutations were introduced into the putative serine protease domain of the tick-borne encephalitis virus NS3 protein and into a possible internal cleavage site within the protein. The influence of these mutations on proteolytic activity of NS3 protein and NS3' protein formation was tested in vitro. It was found that NS3' formation was not dependent on the activity of the NS3 N-terminal serine protease. Mutations affecting the Ser-138 residue of the NS3 protein prohibited cleavage between NS2B and NS3 proteins when the NS2B-NS3 part of the viral genome was expressed in vitro, suggesting the key role of Ser-138 in viral serine protease functioning.