Incidence and risk factors for chronic elevation of alanine aminotransferase levels in HIV-infected persons without hepatitis b or c virus co-infection

Chronic liver disease in human immunodeficiency virus (HIV)-infected patients is mostly caused by hepatitis virus co-infection. Other reasons for chronic alanine aminotransferase (ALT) elevation are more difficult to diagnose.

Interferon-inducible expression of APOBEC3 editing enzymes in human hepatocytes and inhibition of hepatitis B virus replication

Hypermutations in hepatitis B virus (HBV) DNA by APOBEC3 cytidine deaminases have been detected in vitro and in vivo, and APOBEC3G (A3G) and APOBEC3F (A3F) have been shown to inhibit the replication of HBV in vitro, but the presumably low or even absent hepatic expression of these enzymes has raised the question as to their physiological impact on HBV replication. We show that normal human liver expresses the mRNAs of APOBEC3B (A3B), APOBEC3C (A3C), A3F, and A3G. In primary human hepatocytes, interferon alpha (IFN-alpha) stimulated the expression of these cytidine deaminases up to 14-fold, and the mRNAs of A3G, A3F, and A3B reached expression levels of 10%, 3%, and 3%, respectively, relative to GAPDH mRNA abundance. On transfection, the full-length protein A3B(L) inhibited HBV replication in vitro as efficiently as A3G or A3F, whereas the truncated splice variant A3B(S) and A3C had no effect. A3B(L) and A3B(S) were detected predominantly in the nucleus of uninfected cells; however, in HBV-expressing cells both proteins were found also in the cytoplasm and were associated with HBV viral particles, similarly to A3G and A3F. Moreover, A3G, A3F, and A3B(L), but not A3B(S), induced extensive G-to-A hypermutations in a fraction of the replicated HBV genomes. In conclusion, the editing enzymes A3B(L), A3F, and most markedly A3G, which are expressed in liver and up-regulated by IFN-alpha in hepatocytes, are candidates to contribute to the noncytolytic clearance of HBV.

Effects of point mutations in the cytidine deaminase domains of APOBEC3B on replication and hypermutation of hepatitis B virus in vitro

APOBEC3 cytidine deaminases hypermutate hepatitis B virus (HBV) and inhibit its replication in vitro. Whether this inhibition is due to the generation of hypermutations or to an alternative mechanism is controversial. A series of APOBEC3B (A3B) point mutants was analysed in vitro for hypermutational activity on HBV DNA and for inhibitory effects on HBV replication. Point mutations inactivating the carboxy-terminal deaminase domain abolished the hypermutational activity and reduced the inhibitory activity on HBV replication to approximately 40 %. In contrast, the point mutation H66R, inactivating the amino-terminal deaminase domain, did not affect hypermutations, but reduced the inhibition activity to 63 %, whilst the mutant C97S had no effect in either assay. Thus, only the carboxy-terminal deaminase domain of A3B catalyses cytidine deaminations leading to HBV hypermutations, but induction of hypermutations is not sufficient for full inhibition of HBV replication, for which both domains of A3B must be intact.

Blood donor screening: how to decrease the risk of transfusion-transmitted hepatitis B virus?

QUESTIONS UNDER STUDY: The risk of transfusion-transmitted HBV remains significant in Switzerland, where routine screening for hepatitis B virus (HBV) in blood donations relies solely on serological hepatitis B surface antigen (HBsAg) testing. This study was designed to determine the prevalence of anti-hepatitis B core (anti-HBc) and HBV nucleic acid testing (NAT) positive donations in two different Swiss donor populations, to help in deciding whether supplemental testing may bring additional safety to blood products. METHODS: In a first population of donors, 18143 consecutive donations were screened initially for HBsAg, anti-HBc (with one EIA assay) and with HBV NAT in minipools of 24 donations. The screening repeatedly reactive anti-HBc donations were then "confirmed" with two supplemental anti-HBc assays, an anti-hepatitis B surface assay (anti-HBs) and with single donation HBV NAT. In a second population of donors, 4186 consecutive donations were screened initially with two different anti-HBc assays in addition to the mandatory HBsAg screening test. The screening repeatedly reactive donations with at least one anti-HBc assay were tested for anti-HBs. RESULTS: In the first subset of 18143 donations, 17593 (97.0%) were negative for HBsAg, anti-HBc and HBV NAT in minipools. 549 (3.0%) were HBsAg and HBV NAT negative, but repeatedly reactive for anti-HBc. Of these 549 donations, 287 could not be "confirmed" with two additional anti-HBc assays and were negative with an anti-HBs assay, as well as with single donation HBV NAT. Only 211 (1.2% of the total screened donations) were "confirmed" positive with at least one of two supplemental anti-HBc assays. One repeatedly reactive HBsAg donation, from a first-time donor, was confirmed positive for HBsAg and anti-HBc, as well as with single donation HBV NAT. In the second subset of 4186 donations, 4014 (95.9%) were screened negative for HBsAg and for anti-HBc, tested with two independent anti-HBc assays. 172 donations (4.1%) were HBsAg negative but repeatedly reactive with at least one of the two anti-HBc assays. Of these 172 samples, 86 were reactive with the first anti-HBc assay only, 13 were reactive with the second anti-HBc assay only and 73 (1.7% of the total screened donations) were "confirmed" positive with both anti-HBc assays. CONCLUSION: The prevalence of anti-HBc "confirmed" positive donations in the two Swiss blood donor populations studied was low (<2%) and we found only one HBV NAT positive (HBsAg positive) donation among more than 18000. Concerning blood product safety, an increase in the deferral rate of less than 2% of anti-HBc positive, potentially infectious donors, would in our opinion make routine anti-HBc testing of blood donations cost-effective. There is however still a need for more specific assays to avoid an unacceptably high deferral rate of "false" positive donors. In contrast, the introduction of HBV NAT in minipools gives minimal benefit due to the inadequate sensitivity of the assay. It remains to evaluate more extensively the value of individual donation NAT, alone or in addition to anti-HBc, as supplemental testing in the context of several Swiss blood donor populations.

Liver enzyme elevation after lamivudine withdrawal in HIV-hepatitis B virus co-infected patients: the Swiss HIV Cohort Study

Background The principal causes of liver enzyme elevation among HIV-hepatitis B virus (HBV) co-infected patients are the hepatotoxic effects of antiretroviral therapy (ART), alcohol abuse, ART-induced immune reconstitution and the exacerbation of chronic HBV infection. Objectives To investigate the incidence and severity of liver enzyme elevation, liver failure and death following lamivudine (3TC) withdrawal in HIV-HBV co-infected patients. Methods Retrospective analysis of the Swiss HIV Cohort Study database to assess the clinical and biological consequences of the discontinuation of 3TC. Variables considered for analysis included liver enzyme, HIV virological and immunological parameters, and medication prescribed during a 6-month period following 3TC withdrawal. Results 3TC was discontinued in 255 patients on 363 occasions. On 147 occasions (109 patients), a follow-up visit within 6 months following 3TC withdrawal was recorded. Among these patients, liver enzyme elevation occurred on 42 occasions (29%), three of them (2%) with severity grade III and five of them (3.4%) with severity grade IV elevations (as defined by the AIDS Clinical Trials Group). Three patients presented with fulminant hepatitis. One death (0.7%) was recorded. Conclusions HBV reactivation leading to liver dysfunction may be an under-reported consequence of 3TC withdrawal in HIV-HBV co-infected patients. Regular monitoring of HBV markers is warranted if active therapy against HBV is discontinued.

Hepatitis B virus infection is associated with impaired immunological recovery during antiretroviral therapy in the Swiss HIV cohort study

Hepatitis B virus (HBV) infection is a major cause of morbidity and mortality in human immunodeficiency virus (HIV)-infected patients worldwide. It is unclear whether HIV-related outcomes are affected by HBV coinfection. We compared virological suppression and immunological recovery during antiretroviral therapy (ART) of patients of different HBV serological status in the Swiss HIV Cohort Study. CD4 cell recovery during ART was significantly impaired in hepatitis B surface antigen-positive patients and in those with anti-hepatitis B core antigen alone compared with HBV-uninfected patients, despite similar virological efficacy of ART. CD4 increase in patients with resolved HBV infection was similar to that in HBV-uninfected individuals.

A case-control study of hepatitis C virus and its interaction with hepatitis B virus on the development of hepatocellular carcinoma in the USA

Objective. The aim of this study was to assess the independent risk of hepatitis C virus (HCV) infection in the development of hepatocellular carcinoma (HCC). The independent risk of hepatitis B virus (HBV), its interaction with hepatitis C virus and the association with other risk factors were examined.^ Methods. A hospital-based case-control study was conducted between January 1994 and December 1995. We enrolled 115 pathologically confirmed HCC patients and 230 nonliver cancer controls, who were matched by age ($\pm$5 years), gender, and year of diagnosis. Both cases and controls were recruited from The University of Texas M. D. Anderson Cancer Center at Houston. The risk factors were collected through personal interviews and blood samples were tested for HCV and HBV markers. Univariate and multivariate analyses were performed through conditional logistic regression.^ The prevalence of anti-HCV positive is 25.2% in HCC cases compared to 3.0% in controls. The univariate analysis showed that anti-HCV, HBsAg, alcohol drinking and cigarette smoking were significantly associated with HCC, however, family history of cancer, occupational chemical exposure, and use of oral contraceptive were not. Multivariate analysis revealed a matched odds ratio (OR) of 10.1 (95% CI 3.7-27.4) for anti-HCV, and an OR of 11.9 (95% CI 2.5-57.5) for HBsAg. However, dual infection of HCV and HBV had only a thirteen times increase in the risk of HCC, OR = 13.9 (95% CI 1.3-150.6). The estimated population attributable risk percent was 23.4% for HCV, 12.6% for HBV, and 5.3% for both viruses. Ever alcohol drinkers was positively associated with HCC, especially among daily drinkers, matched OR was 5.7 (95% CI 2.1-15.6). However, there was no significant increase in the risk of HCC among smokers as compared to nonsmokers. The mean age of HCC patients was significantly younger among the HBV(+) group and among the HCV(+)/HBV(+) group, when compared to the group of HCC patients with no viral markers. The association between past histories of blood transfusion, acupuncture, tattoo and IVDU was highly significant among the HCV(+) group and the HBV(+)/HCV(+) group, as compared to HCC patients with no viral markers. Forty percent of the HCC patients were pathologically or clinically diagnosed with liver cirrhosis. Anti-HCV(+) (OR = 3.6 95% CI 1.5-8.9) and alcohol drinking (OR = 2.7 95% CI 1.1-6.7), but not HBsAg, are the major risk factors for liver cirrhosis in HCC patients.^ Conclusion. Both hepatitis B virus and hepatitis C virus were independent risk factors for HCC. There was not enough evidence to determine the interaction between both viruses. Only daily alcoholic drinkers showed increasing risk for HCC development, as compared to nondrinkers. ^

Chronic hepatitis B virus coinfection is associated with renal impairment among Zambian HIV-infected adults.

Among 6789 HIV-infected Zambian adults screened for hepatitis B virus (HBV) coinfection, estimated glomerular filtration rate (eGFR) was 50-90 mL/minute/1.73 m(2) in 17.6% and <50 mL/minute/1.73 m(2) in 2.5%. Human immunodeficiency virus/HBV coinfection was associated with eGFR <50 mL/minute/1.73 m(2) (adjusted odds ratio, 1.96 [95% confidence interval, 1.34-2.86]), adjusted for age, sex, CD4(+) count, and World Health Organization disease stage.

Molecular epidemiology of hepatitis B virus infection in Switzerland: a retrospective cohort study.

BACKGROUND Chronic hepatitis B virus (HBV) infection affects up to 7 % of the European population. Specific HBV genotypes are associated with rapid progression to end-stage liver disease and sub-optimal interferon treatment responses. Although the geographic distribution of HBV genotypes differs between regions, it has not been studied in Switzerland, which lies at the crossroads of Europe. METHODS In a retrospective analysis of 465 HBV samples collected between 2002 and 2013, we evaluated the HBV genotype distribution and phylogenetic determinants, as well as the prevalence of serological evidence of hepatitis delta, hepatitis C and HIV infections in Switzerland. Baseline characteristics of patients were compared across their region of origin using Fisher's exact test and ANOVA, and risk factors for HBeAg positivity were assessed using logistic regression. RESULTS The Swiss native population represented 15.7 % of HBV-infected patients living in Switzerland. In the overall population, genotype D was most prevalent (58.3 %), whereas genotype A (58.9 %) was the predominant genotype among the Swiss native population. The prevalence of patients with anti-HDV antibodies was 4.4 %. Patients of Swiss origin were most likely to be HBeAg-positive (38.1 %). HBV genotypes of patients living in Switzerland but sharing the same original region of origin were consistent with their place of birth. CONCLUSIONS The molecular epidemiology of HBV infection in Switzerland is driven by migration patterns and not by the genotype distribution of the native population. The prevalence of positive anti-HDV antibodies in our cohort was very low.

T- and B-cell responses and previous exposure to hepatitis B virus in 'anti-HBc alone' patients.

A serologic response to hepatitis B virus (HBV) defined as 'anti-HBc alone' is commonly observed, but its significance remains unclear. This study aimed to define the relationship between 'anti-HBc alone' serostatus and HBV infection, including HBV-specific T- and B-cell memory responses. We enrolled 31 'anti-HBc alone' patients. Total HBV DNA and cccDNA were tested by nested polymerase chain reaction (PCR) analysis in liver samples from 22 'anti-HBc alone' patients vs controls (chronic or resolved HBV infection), followed by HBsAg/HBcAg immunohistochemical (IHC) staining. IFN-γ secretion by HBV-specific T cells was compared in individuals who were 'anti-HBc alone' (n = 27), resolved HBV (n = 21), chronic HBV (n = 24) and 12 healthy controls using enzyme-linked immunospot (ELISpot) assays. An HBsAg-IgG B-cell ELISpot assay was performed in 'anti-HBc alone' patients before and after one dose of recombinant HBsAg vaccine. The majority (23/31, 74.2%) of the 'anti-HBc alone' individuals were co-infected with HCV. Infrequent intrahepatic total HBV DNA (2/22, 9.1%) and cccDNA (1/22, 4.5%) were detected in biopsies; HBsAg and HBcAg IHC staining was negative. HBV-specific T-cell responses were similar between 'anti-HBc alone' individuals and HBV resolvers. Circulating HBV-memory B-cell responses were detected in all 'anti-HBc alone' individuals, consistent with an HBsAg-specific memory pool. After one HBV vaccine dose, increased anti-HBs antibody levels were observed, accompanied by an expansion of HBsAg-specific memory B cells (P = 0.0226). 'Anti-HBc alone' individuals showed HBV-specific T-cell and memory B-cell responses typical of previous viral exposure and protective memory, suggesting a resolved infection.

The epidemiology of Hepatitis B and Hepatitis C virus infection among college students who are not US/Canadian born in Houston

Introduction. A vast majority of studies conducted in both developed and developing nations have focused on the epidemiology of HBV (Hepatitis B virus) and HCV (Hepatitis C virus) in high-risk populations; low-risk populations have been neglected. Recently Hwang et al conducted a unique large cross-sectional study in American university students that focused on cosmetic procedures and drug use for acquiring these infections among a low-risk young adult population In Houston. ^ Methods. This study is a secondary data analysis of the cross-sectional study conducted by Hwang et al. Data for this anonymous study were collected from 7,960 college students, among whom were the 2,561 non US/Canadian born students included in this study. All students completed a self-administered questionnaire and provided a blood sample. The epidemiology of HBV/HCV and risk factors for acquiring HBV/HCV infection was studied by comparing those with HBV/HCV infection versus those without. Both univariate and multivariate logistic regression was used to analyze the data. ^ Results. Overall prevalence of HBV and HCV infections were 22% and 0.8% respectively. By multivariable analysis, the factors that were independently associated with increased prevalence of HBV infection were increasing age per year (OR=1.06, 95% C.I=1.04-1.08), Black or Asian race (OR=6.21, 95% C.I=3.14-12.27), history of household contact with hepatitis (OR=1.87, 95% C.I=1.15-3.05), and having sexual partner with hepatitis (OR=5.20, 95% C.I=1.5-18.00). For HCV these factors included increasing age per year (OR= 1.08, 95% C.I=1.03-1.14), history of blood transfusion prior to 1991 (OR=25.45, 95% C.I=7.58-85.40), and Injection drug use. (OR=78.15, 95% C.I=12.19-500.85). Cosmetic procedures like tattooing were not significant risk factors for either HBV or HCV infection. ^ Conclusions. In a low-risk adult foreign born population, cosmetic procedures are not significant risk factors for HBV or HCV infection. The prevention strategies of these infections in this population should focus on safe sexual practices/abstinence and HBV vaccination should be provided to adolescents and sexually active adults. ^

Hepatitis B virus HBx protein sensitizes cells to apoptotic killing by tumor necrosis factor α

Persistent infection with hepatitis B virus (HBV) is a leading cause of human liver disease and is strongly associated with hepatocellular carcinoma, one of the most prevalent forms of human cancer. Apoptosis (programmed cell death) is an important mediator of chronic liver disease caused by HBV infection. It is demonstrated that the HBV HBx protein acutely sensitizes cells to apoptotic killing when expressed during viral replication in cultured cells and in transfected cells independently of other HBV genes. Cells that were resistant to apoptotic killing by high doses of tumor necrosis factor α (TNFα), a cytokine associated with liver damage during HBV infection, were made sensitive to very low doses of TNFα by HBx. HBx induced apoptosis by prolonged stimulation of N-Myc and the stress-mediated mitogen-activated-protein kinase kinase 1 (MEKK1) pathway but not by up-regulating TNF receptors. Cell killing was blocked by inhibiting HBx stimulation of N-Myc or mitogen-activated-protein kinase kinase 1 using dominant-interfering forms or by retargeting HBx from the cytoplasm to the nucleus, which prevents HBx activation of cytoplasmic signal transduction cascades. Treatment of cells with a mitogenic growth factor produced by many virus-induced tumors impaired induction of apoptosis by HBx and TNFα. These results indicate that HBx might be involved in HBV pathogenesis (liver disease) during virus infection and that enhanced apoptotic killing by HBx and TNFα might select for neoplastic hepatocytes that survive by synthesizing mitogenic growth factors.

Localization of the C terminus of the assembly domain of hepatitis B virus capsid protein: Implications for morphogenesis and organization of encapsidated RNA

The capsid protein of hepatitis B virus, consisting of an “assembly” domain (residues 1–149) and an RNA-binding “protamine” domain (residues 150–183), assembles from dimers into icosahedral capsids of two different sizes. The C terminus of the assembly domain (residues 140–149) functions as a morphogenetic switch, longer C termini favoring a higher proportion of the larger capsids, it also connects the protamine domain to the capsid shell. We now have defined the location of this peptide in capsids assembled in vitro by engineering a mutant assembly domain with a single cysteine at its C terminus (residue 150), labeling it with a gold cluster and visualizing the cluster by cryo-electron microscopy. The labeled protein is unimpaired in its ability to form capsids. Our density map reveals a single undecagold cluster under each fivefold and quasi-sixfold vertex, connected to sites at either end of the undersides of the dimers. Considering the geometry of the vertices, the C termini must be more crowded at the fivefolds. Thus, a bulky C terminus would be expected to favor formation of the larger (T = 4) capsids, which have a greater proportion of quasi-sixfolds. Capsids assembled by expressing the full-length protein in Escherichia coli package bacterial RNAs in amounts equivalent to the viral pregenome. Our density map of these capsids reveals a distinct inner shell of density—the RNA. The RNA is connected to the protein shell via the C-terminal linkers and also makes contact around the dimer axes.