Epstein-Barr virus uses HLA class II as a cofactor for infection of B lymphocytes

Infection of B lymphocytes by Epstein-Barr virus (EBV) requires attachment of virus via binding of viral glycoprotein gp350 to CD21 on the cell surface. Penetration of the cell membrane additionally involves a complex of three glycoproteins, gH, gL, and gp42. Glycoprotein gp42 binds to HLA-DR. Interference with this interaction with a soluble form of gp42, with a monoclonal antibody (MAb) to gp42, or with a MAb to HLA-DR inhibited virus infection. It was not possible to superinfect cells that failed to express HLA-DR unless expression was restored by transfection or creation of hybrid cell lines with complementing deficiencies in expression of HLA class II. HLA class II molecules thus serve as cofactors for infection of human B cells.     

Use of digoxigenin-labeled RNA probe to test hepatitis A virus antiviral drugs

A nucleic acid hybridization assay was used to evaluate inhibitory activity of antiviral compounds against hepatitis A virus (HAV) in cell culture and compared to radioimmunoassay by analysis of variance procedure. The 5' genomic end of the HM-175 strain was used as digoxigenin-labeled RNA probe. Dot-blot examination showed a reduction of detectable HAV RNA in infected cells when treated with amphotericin B. An antiviral dose-effect was shown by statistical analysis of densitometric measures of hybridization signals. Comparison between molecular hybridization assay and radioimmunoassay by analysis of variance procedure showed the equivalence of both methods. Data previously obtained on selected drugs by antigen and infectious titres determinations were confirmed by hybridization assay and make possible digoxigenin-labeled RNA probe use to measure an antiviral dose-effect for screening of hepatitis A antiviral compounds.     

Spontaneous production of Epstein-Barr virus by B lymphoblastoid cell lines obtained from patients with Sj?gren's syndrome. Possible involvement of a novel strain of Epstein-Barr virus in disease pathogenesis

OBJECTIVE: To investigate the involvement of Epstein-Barr virus (EBV) in the pathogenesis of Sj?gren's syndrome (SS) and to examine whether the spontaneous production of EBV is unique to SS B cell lines. METHODS: B cell lines were established from peripheral blood mononuclear cells (PBMC) of patients with systemic lupus erythematosus, rheumatoid arthritis, and SS. The cord blood immortalization assay, flow cytometric analysis, and polymerase chain reaction (PCR) were used to detect EBV production by B cell lines. RESULTS: SS B cell lines produced EBV at a higher frequency, and in significantly larger amounts, than did other B cell lines. However, no correlation with the amount of EBV DNA in the genome of B cell lines was found. PCR analysis revealed that EBV with a B95-8--like U2 region was dominant in SS B cell lines. CONCLUSION: Spontaneous, massive production of EBV by B cell lines is unique to SS, and may contribute to the polyclonal B cell activation seen in this disease.     

Photochemical inactivation of duck hepatitis B virus in human platelet concentrates: a model of surrogate human hepatitis B virus infectivity

BACKGROUND: Photochemical decontamination of platelet concentrates (PCs) has been demonstrated by the use of 8-methoxypsoralen and ultraviolet A light. Systems for studying the inactivation of blood-borne viruses facilitate the evaluation of photochemical decontamination protocols. STUDY DESIGN AND METHODS: Duck hepatitis B virus (HBV), a model for human HBV, was adapted for the study of hepadnavirus inactivation. A highly specific in vitro infectivity assay used primary duck hepatocyte cultures and was followed by the detection of replicated duck HBV sequences. RESULTS: Duck HBV-infected primary duck hepatocyte cultures produced authentic infectious virus. High-titer (> 10(9) virus genome equivalents/mL) duck HBV-infected sera were completely inactivated in serum or PCs by the use of 100 micrograms per mL of 8-methoxypsoralen and 70 J per cm2 of ultraviolet A light. Intracellular duck HBV (> 4.2 log10) in PCs was also inactivated. Culture results were confirmed by a sensitive duckling infectivity assay that indicated that 6.3 log10 of infectious duck HBV had been inactivated by photochemical decontamination. CONCLUSION: The sensitivity of the culture assay was comparable to that of the duckling assay using polymerase chain reaction gene amplification to detect duck HBV. Duck HBV inactivation in PCs was dependent on the dose of ultraviolet A light and independent of 8-methoxypsoralen concentrations of 100 to 300 micrograms per mL: 100 micrograms per mL 8-methoxypsoralen inactivated 4 to 5 log10 of virus in conjunction with 20 to 40 J per cm2 of ultraviolet A light. The polymerase chain reaction-enhanced duck HBV culture system has utility in optimizing photochemical decontamination protocols.     

Human parvovirus B19 as a causative agent for rheumatoid arthritis

Human parvovirus B19 (B19) DNA was detected in the synovial tissues in 30 of 39 patients with rheumatoid arthritis (RA), and infrequently in those with osteoarthritis and traumatic joints. On the other hand, the expression of the B19 antigen VP-1 was specific (27/27) in RA synovium with active synovial lesions, but not in osteoarthritis and controls. The target cells of B19 were macrophages, follicular dendritic cells, T cells, and B cells, but not synovial lining cells in the synovium. B19-negative bone marrow cells, tonsil cells, and macrophage cell line U-937 cells became positive for the expression of VP-1, and more productive for interleukin 6 and tumor necrosis factor alpha when cocultured with RA synovial cells. The expression of VP-1 and the production of interleukin 6 and tumor necrosis factor alpha was significantly inhibited by the addition of neutralizing antibody for B19, suggesting that B19 detected in RA synovial cells is infective. B19 is involved in the initiation and perpetuation of RA synovitis, leading to joint lesions.     

New antiviral agents in the treatment of chronic hepatitis B and C

Interferon (IFN) is the drug universally used in the treatment of B and C chronic hepatitis. Due to its low efficacy, 40% in the treatment of chronic hepatitis B and 10-20% in the treatment of chronic hepatitis C, and to its adverse events, in some cases severe, new antiviric molecules are being investigated. Lamivudin, famciclovir and the association of ribavirin and IFN are the more relevant and will be clinically accepted in an immediate future. It is also probable that rigid indications for hepatic transplantation in patients with liver cirrhosis by B virus change in the next years due to the use of these new antiviric drugs before and after transplantation. In this revision we analyze the current situation of these new therapies. However, most information come from pilot studies, and multicentric randomized studies are needed to establish firm conclusions about the role that these new therapies are going to play in the treatment of viral chronic hepatitis.     

Characterization of unusual escape variants of hepatitis B virus isolated from a hepatitis B surface antigen-negative subject

Hepatitis B virus DNA was extracted from serial serum samples of a hepatitis B surface antigen-negative patient with antibodies to the core protein as the only marker of an infection with hepatitis B virus. This patient showed no symptoms of hepatic injury. Sequencing of the amplified viral DNA demonstrated multiple amino acid changes clustering in surface-exposed regions of the surface protein. Synthesis and association of the middle (M) and small (S) surface proteins could be shown in vitro. The variant surface antigens were recognized neither by monoclonal antibodies to the surface antigen nor by the vaccinee's sera. Consequences for hepatitis B surface antigen testing and vaccine development are discussed.     

Baculovirus expression of chimeric hepatitis B virus core particles with hepatitis E virus epitopes and their use in a hepatitis E immunoassay

Two hepatitis B core proteins bearing the immunodominant region of the hepatitis E virus (HEV) capsid protein, one at the C terminus of hepatitis B virus core antigen (HBcAg) and the other within the HBcAg immunodominant loop, were constructed. Both chimeric proteins exhibited HEV reactivity, but only the first construct retained HBcAg reactivity. The second construct was used to develop an anti-HEV test which is equivalent to a commercial test for the detection of anti-HEV immunoglobulin G (IgG) but is more sensitive for the detection of anti-HEV IgM.     

The natural course of hepatitis B and hepatitis C virus infection

Chronic hepatitis B and hepatitis C virus infections maintain a significant risk for the development of liver cirrhosis and hepatocellular carcinoma and cause a considerable morbidity in the population. Among patients with chronic HBV infection and histologically confirmed hepatitis the annual incidence of liver cirrhosis is 2%. The risk for hepatocellular carcinoma in chronic HBsAg carriers is elevated about 40-230 fold. 20-30% of patients with chronic HCV infection will develop cirrhosis over 20-30 years. Hepatocellular carcinoma evolves yearly in about 3% of patients with chronic HCV infection and cirrhosis, whereas HCV-carriers without cirrhosis usually do not develop hepatocellular carcinoma. The high incidence of serious sequelae warrants a regular surveillance of chronic virus carriers.     

Use of quantitative assays for hepatitis B e antigen and IgM antibody to hepatitis B core antigen to monitor therapy in chronic hepatitis B

OBJECTIVES: We evaluated the clinical utility of IgM antibody to the hepatitis B (HB) core antigen (anti-HBc) and HB e antigen (HBeAg) serum levels in patients with chronic HB receiving interferon alfa. METHODS: Stored serum from 47 patients with chronic HB participating in a controlled trial of interferon alfa therapy (10 million U three times a week for 16 wk) were analyzed. All were seropositive for HB surface Ag, HBeAg, and HB virus (HBV) DNA before entry. IgM anti-HBc index values and HBeAg standard values were determined by automated microparticle enzyme immunoassay on samples drawn just before therapy and 6 months later. Ten normal subjects were tested as controls. IgM anti-HBc and HBeAg levels were compared to initial serum HBV DNA, DNA polymerase, serum aminotransferase levels, and demographic features. Serial IgM anti-HBc levels were also obtained during and after therapy in 10 responders and five nonresponders, and serial HBeAg levels were also obtained during and after therapy in four responders and four nonresponders. RESULTS: Neither IgM anti-HBc nor HBeAg levels correlated significantly with values for serum HBV DNA, DNA polymerase, aminotransferases, or demographic features. The initial mean IgM anti-HBc level among the 15 responders to therapy (loss of HBeAg and HBV DNA from serum) was no different from that in nonresponders (mean 1.15 vs 1.27, p = not significant). However, the initial mean HBeAg level was significantly lower in responders than in nonresponders (749.4 vs 1356.4, p = 0.019). Among 10 responders, IgM anti-HBc levels decreased progressively over time, so that at latest follow-up (1.5-4 yr later, mean 2.6 yr), the mean had decreased from 1.325 to 0.312 (p = < 0.001). Among five nonresponders, the mean did not change significantly over 1.5-3 yr (mean 2.2 yr) (1.26 vs 1.08, p = not significant). HBeAg values fell in parallel with HBV DNA and DNA polymerase values in four responders tested but remained elevated in four nonresponders. CONCLUSIONS: HBeAg levels, but not IgM anti-HBc levels, are useful in predicting response to interferon alfa, with responders tending to have lower pretreatment HBeAg levels than nonresponders. HBeAg levels may be used to monitor response to interferon alfa in patients with chronic HB.     

The prevalence of HBsAg in hospitalized children as a marker of hepatitis B virus infection]

The aim of this study was to determine the prevalence of hepatitis B surface antigen (HBsAg) in hospitalised children, as specific marker for hepatitis B virus (HBV) infection. Our study group consists of 517 children, 68 of them diagnosed with chronic hepatitis. For HBsAg determination we used an ELISA test (Labsystems); for some children we also tested by ELISA the following markers: the antibodies and anti-hepatitis C virus (HCV) antibodies. From 517 children 24.28% were HBSAg positive and 75% of children with chronic hepatitis were positive for the same marker. Almost 100% of chronic active hepatitis (CAH) patients was positive for HBSAg. CONCLUSIONS: 1. The prevalence of HBsAg was much higher as compared with the healthy population prevalence; it is a clear prove that HBV infection has an important role in chronic hepatitis appearance. 2. For all HBsAg positive patients, it is necessary to determine other markers like HBeAg-anti-HBe antibodies system as well as markers for other viral hepatitis (HDV, HCV). 3. The anti-HBV infection vaccine will reduce significantly the prevalence of HBV and HDV infections; 4. Biological molecular technique, like PCR will be necessary in our country, in the future, even the price is so high, to monitoring the IFN treatment for chronic infection as unique solution for these patients.     

Transcriptional activation of NF-kappa B activity by Epstein-Barr virus (EBV) LMP1 as a selective therapeutic strategy for EBV-associated diseases

Epstein-Barr virus (EBV) has been known to be associated with many malignant tumors, including nasopharyngeal carcinoma (NPC). Previous studies have indicated that an EBV-encoded oncoprotein, latent membrane protein 1 (LMP1), is expressed in many NPC tissues. LMP1 has been shown to stimulate HIV LTR through the two NF-kappa B binding sites within this promoter. In this study, we examined the feasibility of using this property of LMP1 as a therapeutic strategy for the treatment of NPC. This therapy consists of the preferential killing of the LMP1-expressing cells by gene transfer using the NF-kappa B-mediated herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) system. The 800-bp HIV-LTR, which contains two NF-kappa B binding sites, was used to drive the HSVtk gene. Stable C33A cell clones expressing the LMP1 and the HSVtk genes were subjected to the GCV sensitivity test. Results showed that cells expressing both the LMP1 and the HSVtk genes were highly sensitive to GCV treatment. These cells were introduced into nude mice subcutaneously and tumors became palpable within 2 weeks. GCV was then introduced intraperitoneally to these mice and the sizes of the tumors were measured daily. Results showed that the tumors regressed in the group of mice carrying cells that stably expressed both the LMP1 and the HSVtk genes, but not in mice carrying cells containing LMP1 or HSVtk alone. Our data indicate that the HSVtk gene expressed from a NF-kappa B-binding motif-containing promoter that is regulated by LMP1 may be used as an in vivo gene therapy strategy of EBV LMP1-expressing cancers such as NPC.