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Biomedical subjects

W H Gerlich

Publications and source records attributed to W H Gerlich.

At least 73 records · Page 4Linked to original sources
PubMed1993

Genotyping by multiplex polymerase chain reaction for detection of endemic hepatitis B virus transmission.

A nested polymerase chain reaction (PCR) protocol was developed for rapid genotyping of hepatitis B virus (HBV). During the first PCR round, a universal HBV primer pair was used to amplify the entire pre-S region of the HBV genome. Within the pre-S region, many nucleotide exchanges are observed. These are partly correlated to the serological hepatitis B surface antigen subtypes. Five additional subtype-specific primers were selected from that region which, together with two universal non-group-specific primers, generated specific combinations of two to four DNA fragments of defined sizes. By this approach, 55 hepatitis B surface antigen-positive patients from a pediatric oncology unit in Germany were analyzed. Fifty-four patients who had been infected within 2 years had an identical pattern in the multiplex PCR, suggesting a common source of infection and person-to-person transmission within the unit. One child who was infected 5 years later had a different PCR pattern and, therefore, must have been infected from a different source. Furthermore, 109 serum samples taken from pregnant Cameroonian women and 25 serum samples from their babies taken 6 months after birth were analyzed. In one case, mother-to-infant transmission of the virus was demonstrated. Apart from its role in epidemiological studies on HBV, multiplex PCR may also be a useful tool for rapid genetic analysis in other fields if there is a moderate degree of sequence variation which enables the design of specific primers.

Base Sequence↗
PubMed1993

[Risk of hepatitis B virus transmission by highly viremic chronic carriers in schools].

To determine the frequency of hepatitis B virus (HBV) transmission by hepatitis B surface antigen (HBsAg) carriers in school classes 44 highly viremic children were examined over an average period of 5 years. All these HBsAg carriers had been infected with the virus in a hospital endemia during treatment for childhood malignancies. They have been continuously positive for HBeAg with very high HBV-DNA titers of more than 10(8) viral genomes/ml serum. Due to data protection reasons no serologic tests could be done in these school classes. Therefore, the patients and their parents were asked to fill in a questionnaire about any cases of hepatitis in the school classes during the study period. These results were compared with the hepatitis B registrations in the records of the public health offices. No differences were found between the two sources of data. In the school classes of the HBsAg carriers the incidence of hepatitis cases was 0.3 per 1000 pupils per year, which is not different from the hepatitis B morbidity within the general population. Therefore, there is no reason to impose any restrictions on HBsAg carriers in school. In contrast, several cases of HBV transmissions occurred to non-vaccinated family members of the HBV carriers.

Adolescent↗
PubMed1992

Detection of transcriptionally active hepatitis B virus DNA in peripheral mononuclear blood cells after infection during immunosuppressive chemotherapy using the polymerase chain reaction.

Using PCR we have studied mononuclear peripheral blood leucocytes (PMBLs) from HBV-infected immunosuppressed patients in order to detect the presence of HBV genomes. Our results indicate that non-transient PMBL infection is common in immunotolerant carriers. In addition, the presence of pregenomic mRNA sequences suggests that virus replication may take place in PMBLs, possibly implicating the latter as a source of virus after replication has ceased in the liver.

Adolescent↗
PubMed1992

HBc and HBe specificity of monoclonal antibodies against complete and truncated HBc proteins from E. coli.

We have prepared and used monoclonal antibodies against various populations of full-length and truncated hepatitis B core proteins in order to distinguish between epitopes of HBcAg and HBeAg. Our results show that various epitopes are specific for the different proteins. Certain epitopes, however, are ubiquitous to HBc/e proteins and these are probably exposed on the surface of HBc particles.

Antibodies, Monoclonal↗
PubMed1992

Functions of hepatitis B surface proteins.

HBV surface proteins play a number of functional roles in cellular infection, viral synthesis and in immune responses of the host. Three coterminal proteins of differing sizes and three subdomains of the individual molecules can be recognized. In this brief review, functions of the various proteins and domains are described and their significance as potential immunogens is discussed. Although it is apparent that the surface proteins are involved in the development of persistent HBV infections, the underlying mechanisms of liver involvement remain unknown.

Hepatitis B↗
PubMed1992

Absence of free core antigen in anti-HBc negative viremic hepatitis B carriers.

Using enzyme immune assay and immune electron microscopy, we have examined the sera of immune-suppressed anti-HBc negative HBV-infected patients for the presence of HBcAg. Our results suggest that free HBV core particles are absent or present only in minute amounts in the blood of chronic carriers and that at the most, only minimal amounts of core antigen are found on the surface of the virus particles.

Carrier State↗
PubMed1992

Early appearance and biphasic kinetics of IgG antibody against hepatitis C virus protein C100-3.

Antibody to recombinant hepatitis C virus (HCV) protein C100 (anti-C100) was measured for a period of 6 months by enzyme immunoassay in nine prospectively followed non A-nonB (NANBH) cases which occurred after cardiac surgery at a hospital in Rio de Janeiro (Brazil). At least seven cases were infected with HCV; four of these developed chronic hepatitis as shown in liver biopsy at the 6th month after transfusion. The first elevation of alanine aminotransferase (ALT) occurred between 15 and 45 days after transfusion and ALT values remained elevated for 45 days in resolving hepatitis, whereas in chronic cases fluctuation levels were observed until the end of the study. Anti-C100 appeared after 15 to 30 days, decreased after some weeks, and rose finally to high concentrations except in one resolving case where it disappeared. We conclude that both in acute and chronic hepatitis C an early antibody response occurs which may, however, be undetectable in some cases. After several months all chronic and some resolving cases develop a second stronger response.

Adult↗
PubMed1992

Increased growth of permanent mouse fibroblasts in soft agar after transfection with hepatitis B virus DNA.

Previously we have shown that a nontumorigenic mouse hepatocyte line harboring simian virus 40 large tumor antigen (SV 40 TAg) could be converted to a full-malignant phenotype by transfection with HBV DNA. Using a permanent SV 40 TAg-negative mouse fibroblast cell line (LTK-), we studied whether the in vitro-oncogenicity of HBV was dependent on simultaneous expression of SV 40 TAg or not. Three fibroblast lines stably transfected by full-length HBV DNA formed four times more colonies of large size in soft agar than nontransfected LTK- cells. All three clones expressed high levels of HBx protein, but variable levels of other HBV proteins. A second type of clone that was transfected by a partial HBV genome and that expressed HBV surface but no HBx proteins, did not acquire increased growth in soft agar. These data reveal that HBV DNA can enhance malignant growth independent of SV 40 TAg and suggest that HBx protein may act as an HBV oncogene at least in vitro.

Animals↗
PubMed1992

Expression of large hepatitis B envelope protein mutants using a new expression vector.

Aminoterminal deletion mutants of the gene encoding the large hepatitis B surface protein were expressed in COS cells using a new expression vector. The truncated protein showed the same intracellular retention like the wild type protein. The findings show that the secretion block of the protein is not due to its aminoterminal myristylation.

Amino Acid Sequence↗
PubMed1992

Genomic variability in the preS1 region and determination of routes of transmission of hepatitis B virus.

On the basis of published sequence data the preS1 attachment region of hepatitis B virus (HBV) appears to be highly variable. Using a novel method for rapid DNA sequencing by the polymerase chain reaction we screened 34 HBV DNA-positive sera for mutations in a variable part of the preS1 region of the HBV genome. The sequence data were used to analyse potential chains of infection, and strongly supported the expected routes of HBV transmission among patient groups. Furthermore, sequence comparisons permitted sub-genotyping of the viruses. In the 22 cases of subtype adw, we found a very low number of point mutations. This shows that the attachment site of HBV is more highly conserved than that of other blood-transmissible viruses such as human immunodeficiency virus or hepatitis C virus.

Amino Acid Sequence↗
PubMed1992

The preS1 domain of hepatitis B virus and IgA cross-react in their binding to the hepatocyte surface.

Using a solid-phase assay we have demonstrated specific competition between the preS1 sequence of hepatitis B virus and human IgA in their binding to isolated normal human liver plasma membranes, suggesting molecular mimicry. Monoclonal and polyclonal antibodies raised against virus and IgA epitopes were used to detect and map immunological cross-reactivity to the virus sequence involved in liver cell binding. These findings suggest the existence of a common receptor or of closely related receptors for the attachment of HBV and IgA to human liver cells.

Amino Acid Sequence↗