Complement fixing hepatitis B core antigen immune complexes in the liver of patients with HBs antigen positive chronic disease.
(1/2532)
One hundred and fifty-two biopsies from serologically HBsAg positive and negative patients with liver disease were studied in immunofluorescence: for the presence of the surface (HBs) and the core (HBc) antigenic determinants foeterminants of the hepatitis B virus, of immunoglobulins and complement (C) deposits, and for the capacity to fix human C. Circumstantial evidence is presented suggesting that HBc immune-complexes are a relevant feature in the establishment and progression of chronic HBSAg liver disease. C fixation by liver cells was shown in all HBC positive patients with chronic hepatitis; an active form was present in every case, except two with a persistent hepatitis, an inverse ratio of HBc to C binding fluorescence being noted between active chronic hepatitis and cirrhotic patients. HBc without C fixation was observed in only three patients in the incubation phase of infectious hepatitis. IgG deposits were often found in HBc containing, C fixing nuclei. No C binding or IgG deposits were observed in acute self-limited type B hepatitis, in serologically positive patients with normal liver or minimal histological lesions, with and without HBs cytoplasmic fluorescence in their biopsy, or in serologically negative individuals. (+info)
Prevalence of hepatitis B surface antigen and antibody in white and black patients with diabetes mellitus.
(2/2532)
The prevalence of hepatitis B surface antigen (HBSAg) and antibody (anti-HBS) was determined in 531 white and 519 black diabetic outpatients and in appropriate white and black control populations. There was no difference between the prevalence of either HBSAg or anti-HBS in either the white or black diabetics and that in the white and black controls. These findings make it unlikely that the vast majority of patients with diabetes mellitus have either an increased susceptibility to infection by the hepatitis B virus or an impaired ability to clear the virus once they are infected. (+info)
A cellular protein which binds hepatitis B virus but not hepatitis B surface antigen.
(3/2532)
The envelope of hepatitis B virus (HBV) consists of three related proteins known as the large (L), middle (M) and small (S) hepatitis B surface antigens (HBsAg). L-HBsAg has a 108-119 amino acid extension at the N terminus compared with M-HBsAg and contains the preS1 sequence of the HBV envelope. Previous research has identified this region as the likely virus attachment protein which is thought to interact with the cellular receptor for the virus. However, as the receptor has still not been identified unequivocally, we used the preS1 region of L-HBsAg to screen a human liver cDNA library by the yeast two-hybrid system. Several positive clones were isolated which encoded cellular proteins that interacted with the HBV preS1 protein. The specificity was examined in an independent manner in experiments in which baculovirus-derived glutathione S-transferase (GST)-preS1 was incubated with 35S-labelled protein expressed by in vitro translation from the positive clones. The intensity of the interactions using this alternative approach mirrored those observed in the yeast two-hybrid system and two proteins (an unidentified protein and a mitochondrial protein) were selected for further study. The specificity of the binding reaction between the preS1 protein and these two proteins was further confirmed in a competition assay; HBV purified from serum, but not purified HBsAg, was able to compete with preS1 and thus block GST-preS1 binding to the unidentified protein but not to the mitochondrial protein. The unidentified protein was then expressed as a fusion protein with GST and this was able to bind HBV virions in a direct manner. (+info)
Leucocyte migration inhibition with inner and outer membranes of mitochondria and insoluble hepatocyte surface membranes prepared from rat liver in patients with chronic hepatitis and cirrhosis.
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Patients with chronic liver disease were tested for delayed hypersensitivity to the outer and the inner membranes of mitochondria (OMM and IMM) and the insoluble hepatocyte-surface membranes (IHSM), prepared from rat livers, by means of leucocyte migration inhibition technique. Positive reaction to OMM was found in 37% of patients with chronic persistent hepatitis and 35% of those with chronic active hepatitis and 43% of those with liver cirrhosis (P less than 0-05). That to IMM was 55%, 43% and 36% (P less than 0-05) and to IHSM was 37%, 47% and 45% respectively (P less than 0-05). IHSM was found to contain liver-specific components and patients with positive response to IHSM did not reveal at all a positive reaction to rat renal cell-surface membranes. The incidence of positive response to IHSM was significantly higher (54-2%) in patients with the present or previous infection with HBAg than in HBAg-non-infected patients (21-4%) (P less than 0-05). And there seemed to be a good correlation between a degree of cellular response to purified HBsAg and that to IHSM in these HBAg-infected patients. No correlation, however, was found between that to purified HBsAg and that to OMM or IMM in the same patients. This suggested that the cellular response to either HBsAg or IHSM, both related closely, may play a role in the perpetuation of chronic liver disease. (+info)
Hepatitis B virus (HBV)-transgenic mice as an investigative tool to study immunopathology during HBV infection.
(5/2532)
An overview is given regarding the use of hepatitis B virus (HBV) transgenic mice as an animal model of the HBV-carrier state. Initially, we show how HBV-transgenic mice have contributed insights into the immunopathobiological processes during HBV infection and later, we show how this new information from the experiments with HBV-transgenic mice could be used to develop new methods to combat HBV infection. By microinjecting the full or selected parts of the HBV-genome into the fertilized eggs of inbred mice, different laboratories have developed different lines of HBV-transgenic mice, which express products of the HBV genome and also show signs of HBV replication. Studies in HBV-transgenic mice have provided insights into the process of destruction of hepatocytes, the critical role of cytokines in controlling HBV replication and gene expression, mechanisms underlying the immune response defect in chronic HBV-carriers and the critical role of antigen presenting cells (APC), especially that of antigen presenting dendritic cells in persistent HBV infection. All this new information has given us a better understanding about HBV immunopathobiology, and has led to the development of new therapeutic approaches to combat HBV infection. (+info)
Low prevalence of hepatitis B markers among Mexican female sex workers.
(6/2532)
OBJECTIVES: To estimate the prevalence and associated risk factors of hepatitis B virus (HBV) serological markers in female sex workers (FSW) in Mexico City. METHODS: The study population consisted of 1498 FSW who attended a detection centre for human immunodeficiency virus (HIV) in Mexico City, between January and October 1992. Study participants responded to a standardised questionnaire and provided a blood sample for serology of syphilis, HIV, and HBV. RESULTS: A total of 0.2% (95% CI 0.1-0.3) of the population were hepatitis B surface antigen (HBsAg) carriers. The general prevalence of antibodies to hepatitis B core antigen (anti-HBc) was 6.3% (95% CI 5.5-7.1). This marker of previous exposition to HBV, was independently associated by logistic regression multivariate analysis with age, working in the street, and history of blood transfusion (BT) before 1987 (OR 4.8, 95% CI 2.1-11.3). Syphilis prevalence was 7.6% (95% CI 6.2-8.9) and HIV prevalence was 0.1% (95% CI 0-0.3). CONCLUSIONS: The prevalence of HBV infection in this group of Mexican FSW is lower than previously reported in other countries. In addition, the frequency of HBsAg carriers is similar to that in the general Mexican population. The absence of two major risk factors for HBV transmission in this group of FSW--that is, injecting drug use and anal intercourse, could help to explain this finding. However, the positive association between anti-HBc and history of blood transfusion demonstrated here, highlights the need to reinforce strict control of blood supplies in Mexico. (+info)
Intracellular retention of hepatitis B virus surface proteins reduces interleukin-2 augmentation after genetic immunizations.
(7/2532)
We have previously shown that hepatitis B virus (HBV) surface antigens (HBsAgs) are highly immunogenic after genetic immunization. Compared to the secreted middle HBV surface proteins (MHBs) or small HBV surface proteins (SHBs), the nonsecreted large HBV surface protein (LHBs), however, induced significantly weaker humoral and cellular immune responses that could not be augmented by genetic coimmunizations with cytokine expression plasmids. In order to understand the mechanisms underlying this phenomenon, we examined the effect of coimmunizations with an interleukin-2 (IL-2) DNA expression plasmid on the immunogenicity at the B- and T-cell level of nonsecreted wild-type LHBs, a secreted mutant LHBs, wild-type SHBs, and a nonsecreted mutant SHBs. Coimmunizations of mice with plasmids encoding wild-type SHBs or the secreted mutant LHBs and IL-2 increased anti-HBs responses, helper T-cell proliferative activity and cytotoxic T-lymphocyte killing. By contrast, coimmunizations of plasmids encoding wild-type LHBs or nonsecreted mutant SHBs and IL-2 had no significant effects on immune responses. Interestingly, mice immunized with cytokine expression plasmids 14 days after the injection of the wild-type LHBs plasmid showed augmented immune responses compared to animals simultaneously injected with both expression constructs. Anti-HBs responses in mice injected with plasmids encoding secreted forms of HBsAgs were detectable about 10 days earlier than those in mice immunized with plasmids encoding nonsecreted forms of HBsAgs. Based on these observations, we conclude that cytokines produced by DNA plasmids at the initial site of antigen presentation cannot augment LHBs specific immune responses because LHBs is not produced at high enough levels or is not accessible for uptake by antigen-presenting cells. (+info)
Analysis of the pre-S2 N- and O-linked glycans of the M surface protein from human hepatitis B virus.
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The surface antigen of hepatitis B virus comprises a nested set of small (S), middle (M), and large (L) proteins, all of which are partially glycosylated in their S domains. The pre-S2 domain, present only in M and L proteins, is further N-glycosylated at Asn-4 exclusively in the M protein. Since the pre-S2 N-glycan appears to play a crucial role in the secretion of viral particles, the M protein may be considered as a potential target for antiviral therapy. For characterization of the pre-S2 glycosylation, pre-S2 (glyco)peptides were released from native, patient-derived hepatitis B virus subviral particles by tryptic digestion, separated from remaining particles, purified by reversed-phase high performance liquid chromatography, and identified by amino acid and N-terminal sequence analysis as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Pre-S2 N-glycans were characterized by anion exchange chromatography, methylation analysis, and on target sequential exoglycosidase digestions in combination with MALDI-TOF-MS, demonstrating the presence of partially sialylated diantennary complex-type oligosaccharides. In addition, the pre-S2 domain of M protein, but not that of L protein, was found to be partially O-glycosylated by a Gal(beta1-3)GalNAcalpha-, Neu5Ac(alpha2-3)Gal(beta1-3)GalNAcalpha-, or GalNAcalpha-residue. The respective O-glycosylation site was assigned to Thr-37 by digestion with carboxypeptidases in combination with MALDI-TOF-MS and by quadrupole time-of-flight electrospray mass spectrometry. Analytical data further revealed that about 90% of M protein is N-terminally acetylated. (+info)