PubMed Health⌕ Search

Biomedical subjects

C Brechot

Publications and source records attributed to C Brechot.

At least 145 records · Page 8Linked to original sources
PubMed1985

Relationship between HBcAg in serum and liver and HBV replication in patients with HBsAg-positive chronic liver disease.

The expression of hepatitis B core antigen (HBcAg) in serum and in hepatocytes was evaluated in relation to HBV replication. Fifty chronic HBsAg carriers with histological evidence of liver disease were studied, including 24 HBeAg-positive patients, 2 HBeAg/anti-HBe-negative patients, and 24 anti-HBe-positive cases, two of them with evidence of delta agent infection. Serum HBV-DNA was evaluated in all patients and related to HBcAg examined at the same time in frozen liver biopsies by immunofluorescence and to HBcAg detected in the corresponding serum by a recently developed radioimmunoassay. HBV-DNA was present in serum in 20 (83%) HBeAg-positive patients, all positive for serum HBeAg, whereas liver core antigen was detected in 14 (73%) of 19 cases. Among HBeAg-negative patients, 50% showed the presence of circulating DNA viral sequences, and HBcAg was identified in five of 26 (19%) cases in serum and in six of 24 (25%) in the liver respectively. In 15 patients, liver fragments permitted examination in parallel by immunofluorescence for HBcAg and molecular hybridization for viral DNA in liver cells. A DNA pattern characteristic of viral replication was found in cases with evidence of active virion production, independently from HBeAg and anti-HBe, and in these patients HBcAg was present both in serum and in hepatocytes. In two cases with free HBV-DNA, without evidence of replicative activity, core antigen was not detected in the liver, but in one patient HBcAg was found in the serum. A similar finding was also noted in another patient, in whom the hybridization pattern was consistent with integration of viral genome into high-molecular-weight cellular DNA. Whether serum HBcAg detected in these patients without HBV-DNA in serum reflects the presence of defective viral particles or of core antigen released as a viral protein remains to be determined.

Chronic Disease↗
PubMed1985

Hepatitis B virus multiplication in the absence of usual serological markers. A study of 146 chronic alcoholics.

The possible role of HBV infection in the progression of alcoholic liver disease remains debated. However, serum HBV markers in alcoholics, although present with a high frequency, mainly consist of anti-HBs and/or anti-HBc antibodies. In order to detect an HBV multiplication that could be missed by the usual markers, we looked for HBV-DNA in the serum of 146 chronic alcoholics; the results were compared with those of the usual serological HBV markers. Sixty-eight of the 146 patients could be studied for HBV-DNA both in the liver and the serum. The 146 alcoholics were divided in 48 with normal liver function (group I); 67 with non-cirrhotic alcoholic liver disease (group II); 31 with alcoholic cirrhosis (group III). Among the 146 patients, 17 had a viral multiplication reflected by serum positive HBV-DNA, as against none of 100 healthy controls (P less than 0.01). Six of the 17 had a normal liver function (6/48 = 12.5%), 7 were of group II (7/67 = 10.4%) and 4 had cirrhosis (4/31 = 12.9%). Serum HBV-DNA was associated with HBsAg in 3 occasions; in addition serum HBV-DNA was also present in 5 HBsAg-negative patients with anti-HBc and/or anti-HBs and even in 9 without any usual HBV marker. The overall prevalence of HBV markers in the 146 patients went from 30.8% to 37.0% when serum HBV-DNA was taken into account; it was similar in the 3 groups studied. Eight patients, of the 68 studied, were liver HBV-DNA-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Detection of hepatitis B virus DNA in mononuclear blood cells.

The Southern transfer hybridisation technique was used to test mononuclear blood cells for hepatitis B virus DNA. Viral DNA sequences were detected in mononuclear cells of 10 out of 16 patients with hepatitis B virus infection and in none of 21 normal controls. Blood contamination was excluded by the absence of hepatitis B virus DNA in the corresponding serum samples in all cases. Free monomeric hepatitis B virus DNA was found in three patients positive for hepatitis Be antigen (HBeAg) and one positive for anti-HBe, and integrated hepatitis B virus DNA was present in four patients positive for anti-HBe. In two other patients the small size of the samples did not allow a distinction between free and integrated viral DNA. The state of the virus in the mononuclear cells seemed to correlate with the HBeAg or anti-HBe state, as has been noted in the liver. These results indicate that hepatitis B virus may infect mononuclear blood cells, thereby expanding the tissue specificity of this agent beyond the liver, as has been reported for pancreatic, kidney, and skin tissue. They also suggest that hepatitis B virus infection of mononuclear cells might be related to immunological abnormalities observed in carriers of the virus.

Autoradiography↗
PubMed1984

Multiplication of hepatitis B virus in fulminant hepatitis B.

The presence in serum of hepatitis B e antigen (HBeAg) and hepatitis B virus DNA, which are each regarded as reflecting multiplication of hepatitis B virus, were looked for one to five days after the onset of hepatic encephalopathy in 64 patients with fulminant hepatitis B. HBeAg and hepatitis B virus DNA were found in the serum of only 24 (37%) and six (9%) patients, respectively. Hepatitis B virus DNA was absent from the serum in all 13 patients positive for anti-HBs. These findings indicate that replication of hepatitis B virus stopped after the onset of hepatic encephalopathy in most of the patients and support the view that an enhanced immune response stops the replication. Agents that inhibit viral multiplication would probably not have any effect at this stage of the disease.

Adolescent↗
PubMed1984

Detection of hepatitis B virus DNA in pancreas, kidney and skin of two human carriers of the virus.

Using the Southern blot technique, we have analysed the presence and state of hepatitis B virus (HBV) DNA in non-hepatic tissue from two human HBV carriers. HBV DNA sequences were detected in the pancreas, kidney and skin, demonstrating HBV infection of these organs. Moreover, the restriction DNA patterns were consistent with the integration of these viral sequences into high molecular weight DNA. These results demonstrate that HBV infection is not restricted to the liver.

Aged↗
PubMed1983

Characterization of integrated hepatitis B viral DNA cloned from a human hepatoma and the hepatoma-derived cell line PLC/PRF/5.

Recombinant phage clones carrying integrated hepatitis B virus (HBV) DNA sequences have been isolated from two phage libraries made from human DNA of a hepatoma and a hepatoma-derived cell line. One clone from each library has been characterized both by restriction mapping and by electron microscopy. In one clone there is at least one complete and uninterrupted HBV genome, and in the other the HBV sequences are composed of two major subgenomic fragments inverted with respect to each other. The host-virus junctions are localized within the positions 1,700-2,600 base pairs on the physical map of the free viral genome. The pre-S/S (surface antigen gene) region is conserved between the two clones. The two clones do not have common cellular sequences nor do they contain cellular homologues to six retroviral oncogenes. For one clone, the hepatitis B surface antigen gene was found to be functional when introduced into mouse thymidine kinase-negative cells by transfection.

Carcinoma, Hepatocellular↗
PubMed1983

Hepatitis B virus DNA in children's liver diseases: detection by blot hybridisation in liver and serum.

Molecular hybridisation using cloned hepatitis B virus DNA (HBV DNA) was applied to liver and serum samples from 46 children (39 with liver diseases and seven controls) for detection of HBV DNA sequences, free and integrated into the liver cell genome. HBV DNA integration was observed in 10 children. The young age of some of these cases indicates that such integration can occur early in liver disease and is not related to the duration of viral infection. Thirteen children exhibited serological evidence of active viral multiplication. All but one had free HBV DNA in liver tissue and integrated HBV DNA sequences were found in four cases. Integrated HBV DNA sequences alone were also detected in three children with neither HBV-antigens nor HBV DNA in serum. One had inactive cirrhosis, and the two others, chronic active hepatitis. Consequently DNA hybridisation may be useful for diagnosis, in the absence of serological signs of HBV infection; its specificity was enhanced in the present investigation by negative results in six children with autoimmune chronic active hepatitis. Taken together, the above results imply that HBV-DNA integration can occur in both active and inactive liver disease. Integrated HBV DNA was also observed in the liver of three children with fatal hepatic failure who presented with antibodies to HBsAg and/or to hepatitis B core antigen in the serum. This finding raises the question of the relationship between the host immune factors and the state of HBV DNA.

Adolescent↗
PubMed1983

Further studies on production and characterization of HBsAg derived from a human hepatoma cell line (PLC/PRF/5).

Four aspects for the use of PLC/PRF/5 cell line as an alternative source of HBsAg for hepatitis B vaccine production were assayed in this study: improvement in HBsAg production with chemical inducers, tests for the presence of hepatitis B virions, antigenic topology of HBsAg polypeptides and immunogenicity of HBsAg in guinea pigs. 10(-6) M dexamethasone and/or 10(-4) M sodium butyrate treatments enhanced HBsAg production by a factor of approximately two when compared with untreated cells. Particles of 35 nm diameter produced by PLC/PRF/5 cells were observed at a CsCl density of 1.22-1.24, associated with typical HBsAg 22 nm spheres. These particles did not contain HBV DNA as proved by negative results of hybridization using cloned HBV/DNA as a probe. Western blot analysis revealed that only polypeptides P 22000 (P1) and P 26000 (P2) were specifically recognized by a human anti-HBs serum, irrespective of the origin of HBsAg, i.e. human serum or PLC/PRF/5 hepatoma cell line. HBsAg purified from PLC/PRF/5 cell line was immunogenic in guinea pigs. However, the humoral response was delayed and lower in terms of anti-HBs titers when compared to the response obtained after immunization with a licensed hepatitis B vaccine (HEVAC B, Institut Pasteur Production).

Animals↗
PubMed1981

Detection of hepatitis B virus DNA in liver and serum: a direct appraisal of the chronic carrier state.

The detection of hepatitis B virus (HBV) DNA in the liver and the serum permits direct study of the interaction between the virus and the liver cell. 40 HBV chronic carriers were studied by the blot technique of Southern to detect HBV DNA, and the results were compared with the serological status and histological status of the patients. It was possible to define two different chronic carrier states. The first is characterised by free viral DNA in the liver, with viral DNA and hepatitis B e antigen (HBeAG) in the serum; integrated HBV DNA is also present, at least in some patients. The second carrier state is characterised by the presence of only integrated HBV DNA sequences in the liver: viral DNA and HBeAg are not present in the serum. In one HBeAg-negative patient, however, free HBV DNA was detected in the liver and HBV DNA was present in the serum. The hybridisation technique appears to be a very sensitive test which could reflect viral multiplication better than HBeAg radioimmunoassay. Since a needle biopsy sample provides sufficient tissue for the Southern blot technique, it should be useful in understanding chronic hepatitis, the selection of patients for antiviral therapy, and the estimation of its efficiency.

Autoradiography↗
PubMed1981

Structure and expression of the hepatitis B virus genome.

By fusion of the hepatitis B virus (HBV) surface antigen (HBsAg) gene to that of the E. coli lac Z gene carried by a phage lambda derivative, expression of HBsAg antigenic determinants was obtained and carried by a 138,000 dalton fusion polypeptide. Such a protein could be ultimately useful for second generation vaccine production. HBsAg gene expression was studied in eukaryotic cells using the mouse L cell (tk-) system. Cotransformation using a plasmid carrying two copies of the HBV genome in a tandem, head-to-tail arrangement (pCP10) and the cloned HSV-1 tk gene resulted in the excretion of 22 nm HBsAg particles in the supernatant. No other HBV markers were detected. These particles possess the same characteristics as the human serum particles (morphology, diameter, density, antigenicity). The purified HBsAg particles from L cells were found to be highly immunogenic in mice. HBV mRNA transcripts from these cells were analysed by Northern blotting. A major species of 2,300 bases was detected. This was mapped on the genome by hybridization with subgenomic fragments and in the L cell system using a series of plasmid derivatives carrying insertions at specific sites in the HBV genome and assaying for HBsAg expression. Thus the HBsAg gene promotor was localized between positions 2,400-2,800. Indeed there is only one TATA like sequence in this region, starting at position 2,776.

Animals↗
PubMed1980

Presence of integrated hepatitis B virus DNA sequences in cellular DNA of human hepatocellular carcinoma.

Hepatitis B virus (HBV) may be one of the agents involved in the aetiology of human primary liver cancer. This hypothesis is supported by (1) the similarity between the geographical distribution of chronic carriers of the viral surface antigen (HBsAg) and that of hepatocellular carcinoma (HCC); (2) the increase in the prevalence of HBV markers in serum of patients with primary liver cancer when compared with the general population; (3) the observation that HBV infection precedes the development of the tumour. Moreover, these epidemiological indications of an association between HBV infecton and hepatocellular carcinoma are supported by the detection of HBV markers such as HBsAg or viral DNA sequences, although in a non-integrated form in tumour tissue. To study the relationship between HBV and primary liver cancer further, we looked for the presence of free or integrated viral DNA in tumour tissue of human hepatocellular carcinomas and in a HBsAg-producing human hepatoma cell line. Using the blot-transfer hybridization technique and cloned HBV DNA as a probe, we have now demonstrated that the viral DNA is integrated in the cellular genome both in tumour tissue and in a hepatoma cell line.

Carcinoma, Hepatocellular↗
PubMed1980

Hepatitis B core antigen in hepatocytes of patients with chronic active hepatitis.

Hepatitis B core antigen was demonstrated in the hepatocytes of 28 of 40 patients with chronic active hepatitis in whose sera hepatitis B surface antigen was not detectable by radioimmunoassay. This finding suggests that in these patients, despite hepatitis B surface antigen being undetectable in serum, the liver disease is the consequence of chronic infection with hepatitis B virus.

Adult↗