10 Worldwide prevalence and prevention of hepatitis c

Challenge of hepatitis C in Egypt and hepatitis B in Mauritania

Egypt has one of the highest prevalence rates of hepatitis C virus (HCV) in the world, mostly with genotype 4 that is highly associated with severe fibrosis. As a consequence, hepatocellular carcinoma has become the leading cause of cancer in this country. Mauritania is a highly endemic area for hepatitis B virus (HBV). HBV and HCV could both be iatrogenically transmitted through infected blood products, infected needles, and medical equipment improperly sterilized. Adequate and efficient healthcare and public health measures with good surveillance programs, access for screening, prevention strategies, and successful treatment are needed to halt the spread of these diseases. Herein, we have reviewed the epidemiology, modes of transmission, predisposing factors, and novel treatment modalities of these viruses. We have proposed practices and interventions to decrease the risk of transmission of HCV and HBV in the affected countries, including strict adherence to standard precautions in the healthcare setting, rigorous education and training of patients and healthcare providers, universal screening of blood donors, use of safety-engineered devices, proper sterilization of medical equipment, hepatitis B vaccination, as well as effective direct-acting antiviral agents for the treatment of HCV.

Determinants of Infection Outcome in HCV-Genotype 4

Hepatitis C virus (HCV) infection represents a worldwide health problem and has been for long an attractive point of research due to diversity among different genotypes regarding unique geographical distribution and diverse treatment outcome. HCV is considered a major cause of chronic liver disease and cirrhosis, which leads to liver failure and hepatocellular carcinoma requiring liver transplantation. Of the HCV genotypes identified, HCV genotype 4 (HCV-4) is the least studied. HCV-4 is responsible for ∼10% of HCV infections and is common in the Middle East and Africa; recently it is increasingly prevalent in European Countries. HCV-4 is a continuing epidemic in Egypt, having the highest prevalence of HCV worldwide. "Know your epidemic, know your response" concept necessitates better understanding of HCV-4 characteristics to control disease dissemination and progression, which compromises the life quality of chronic HCV-infected patients. In this review, we discuss the epidemiology, natural history, and treatment options for patients with HCV-4 infection.

Prevalence of Blood-Borne Viruses in Health Care Workers of a Northern District in Pakistan: Risk Factors and Preventive Behaviors

Background. Blood-borne viral infections like viral hepatitis are highly prevalent in Pakistan. There is also a potential threat of human immunodeficiency virus (HIV) spread in the country. Health care workers (HCWs) are a high risk population for acquiring such viral infections and potential spread to the patients. This study aimed to determine the frequency of three blood-borne viruses: HCV, HBV, and HIV in HCWs of district Malakand in northern Khyber Pakhtunkhwa (KPK) province of Pakistan. Moreover, risk factors and preventive behaviors among HCWs were investigated in detail. Materials and Methods. Prevalence was investigated using serological assays followed by real time polymerase chain reaction (RT-PCR) based characterization. A total of 626 health care workers working at 17 different health care units, belonging to 6 different job categories, were included in this study. Results. HIV was not detected in the HCWs while rate of prevalence of HCV and HBV was far less (0.8 % and 0.64 %, resp.) as compared to general population (4.7%–38%). The majority of HCWs were aware of the mode of spread of these viruses and associated risk factors. Needle stick injury was found to be the most important risk factor for possible acquisition of these infections.

Nonstructural protein 5A (NS5A) and human replication protein A increase the processivity of hepatitis C virus NS5B polymerase activity in vitro

The precise role(s) and topological organization of different factors in the hepatitis C virus (HCV) RNA replication complex are not well understood. In order to elucidate the role of viral and host proteins in HCV replication, we have developed a novel in vitro replication system that utilizes a rolling-circle RNA template. Under close-to-physiological salt conditions, HCV NS5BΔ21, an RNA-dependent RNA polymerase, has poor affinity for the RNA template. Human replication protein A (RPA) and HCV NS5A recruit NS5BΔ21 to the template. Subsequently, NS3 is recruited to the replication complex by NS5BΔ21, resulting in RNA synthesis stimulation by helicase. Both RPA and NS5A(S25-C447), but not NS5A(S25-K215), enabled the NS5BΔ21-NS3 helicase complex to be stably associated with the template and synthesize RNA product in a highly processive manner in vitro. This new in vitro HCV replication system is a useful tool that may facilitate the study of other replication factors and aid in the discovery of novel inhibitors of HCV replication.

IMPORTANCE

The molecular mechanism of hepatitis C virus (HCV) replication is not fully understood, but viral and host proteins collaborate in this process. Using a rolling-circle RNA template, we have reconstituted an in vitro HCV replication system that allows us to interrogate the role of viral and host proteins in HCV replication and delineate the molecular interactions. We showed that HCV NS5A(S25-C447) and cellular replication protein A (RPA) functionally cooperate as a processivity factor to stimulate HCV replication by HCV NS5BΔ21 polymerase and NS3 helicase. This system paves the way to test other proteins and may be used as an assay for discovery of HCV inhibitors.

Hepatitis C virus-associated insulin resistance: pathogenic mechanisms and clinical implications

It is now widely recognized that chronic hepatitis C is a metabolic disease, strongly associated with Type 2 diabetic mellitus and insulin resistance (IR). Chronic hepatitis C virus (HCV) infection promotes IR mainly through interfering with the insulin signaling pathway in hepatocytes, increasing the inflammatory response with production of cytokines such as TNF-α and IL-6, and increasing oxidative stress. Accumulated evidence indicates that HCV-associated IR may lead to fibrosis progression, resistance to antiviral therapy, hepatocarcinogenesis and extrahepatic manifestations. Thus, HCV-associated IR is a therapeutic target at any stage of HCV infection. However, specific pharmaceutical treatments of IR are still being evaluated in clinical trials, but available data do not warrant their use in all chronic hepatitis C patients with IR.

Incidence and nature of infectious disease in patients treated with anti-TNF agents

Tumor necrosis factor alpha (TNF-alpha) inhibitors offer a targeted therapeutic strategy that contrasts with the nonspecific immunosuppressive agents traditionally used to treat most inflammatory diseases. These biologic agents have had a significant impact in ameliorating the signs and symptoms of inflammatory rheumatoid disease and improving patient function. From the onset of clinical trials, a central concern of cytokine blockade has been a potential increase in susceptibility to infections. Not surprisingly, a variety of infections have been reported in association with the use of TNF-alpha inhibitor agents. In particular, there is evidence suggesting an increased rate of granulomatous infections in patients treated with monoclonal TNF-alpha inhibitors. This review provides the incidence and nature of infections in patients treated with TNF-alpha inhibitor agents and reminds the clinician of the required vigilance in monitoring patients.

Antibody to hepatitis B core antigen as a screening test for occult hepatitis B virus infection in Egyptian chronic hepatitis C patients

PURPOSE

The presence of hepatitis B virus (HBV) DNA in liver tissue and/or in serum in the absence of detectable hepatitis B surface antigen (HBsAg) is called occult HBV infection. This pattern was identified in patients with chronic hepatitis C virus (HCV) infection. The aim of this study was to determine the role of antibodies to hepatitis B core antigen (anti-HBc) as a screening test for occult HBV infection in Egyptian chronic HCV patients.

METHODS

One hundred chronic HCV patients negative for HBsAg were included and subdivided into two groups according to anti-HBc-IgG seroreactivity. Group A included 71 patients positive for anti-HBc (53 men and 18 women, mean age +/- SD 48.8 +/- 9.6 years), and group B included 29 patients negative for anti-HBc (18 men and 11 women, mean age +/- SD 46.6 +/- 11.7 years). All patients were subjected to full clinical assessment, routine laboratory investigations, abdominal ultrasonography and quantification of HBV-DNA by real-time PCR.

RESULTS

Chronic HCV patients positive for anti-HBc have more severe liver disease compared with anti-HBc negative patients. Although HBV-DNA in the serum was detected in 22.5% of anti-HBc-positive chronic HCV patients, it was not detected in any of anti-HBc-negative chronic HCV patients. There was no significant difference in any of the clinical and laboratory data tested between anti-HBc-positive patients with and without HBV-DNA in the serum.

CONCLUSION

A significant number of patients with anti-HBc had detectable levels of HBV-DNA in the serum. Egyptian chronic HCV patients have a high prevalence of occult HBV infection.

Evidence for a complex mosaic genome pattern in a full-length hepatitis C virus sequence

The genome of the hepatitis C virus (HCV) exhibits a high genetic variability. This remarkable heterogeneity is mainly attributed to the gradual accumulation of mutational changes, whereas the contribution of recombination events to the evolution of HCV remains controversial so far. While performing phylogenetic analyses including a large number of sequences deposited in the GenBank, we encountered a full-length HCV sequence (AY651061) that showed evidence for inter-subtype recombination and was, therefore, subjected to a detailed analysis of its molecular structure. The obtained results indicated that AY651061 does not represent a "simple" HCV 1c isolate, but a complex 1a/1c mosaic genome, showing five putative breakpoints in the core to NS3 regions. To our knowledge, this is the first report on a mosaic HCV full-length sequence with multiple breakpoints. The molecular structure of AY651061 is reminiscent of complex homologous recombinant variants occurring among other members of the flaviviridae family, e.g. GB virus C, dengue virus, and Japanese encephalitis virus. Our finding of a mosaic HCV sequence may have important implications for many fields of current HCV research which merit careful consideration.

Long-term effect of interferon alpha-2b plus ribavirin therapy on incidence of hepatocellular carcinoma in patients with hepatitis C virus-related cirrhosis

We assessed the efficacy of interferon (IFN) alpha-2b plus ribavirin therapy in patients with hepatitis C virus (HCV)-related cirrhosis, and elucidated the risk factors for the development of hepatocellular carcinoma (HCC) to determine whether these therapies might reduce the incidence of HCC. One hundred and thirty-two HCV-cirrhotic patients receiving IFN alpha-2b (3 or 5 MU thrice weekly) and oral ribavirin (1,000-1,200 mg/day) for 24 or 48 weeks were analysed. Cumulative incidence of HCC was estimated by the Kaplan-Meier method. The prognostic relevance of clinical variables and HCC occurrence was evaluated by univariate analysis with the log-rank test and by multivariate Cox's regression analysis. A total of 116 patients completed the treatment and 73 (55%) achieved a sustained virological response (SVR). Stepwise logistic regression analysis showed that nongenotype 1b (P < 0.001) and low viral load (P = 0.018) were independent variables of SVR. During a median follow-up period of 37 (12-63) months, HCC developed in 11 patients with non-SVR and five with SVR (P = 0.0178), whereas there was no difference between those with transient biochemical response and nonresponse (P = 0.5970). The Kaplan-Meier method also showed that old age (>or=60 years) (P = 0.0034) and genotype 1b (P = 0.0104) were associated with HCC occurrence. Using Cox's regression analysis, non-SVR (odds ratio = 3.521, P = 0.036), male (odds ratio = 6.269, P = 0.011) and old age (odds ratio = 3.076, P = 0.049) were independent significant risk factors contributing to HCC development. Our results suggest that achieving SVR by IFN alpha-2b plus ribavirin therapy may decrease the incidence of HCC in patients with HCV-related cirrhosis.

Chimeric monoclonal antibodies to hypervariable region 1 of hepatitis C virus

Two chimeric monoclonal antibodies (cAbs), 2P24 and 15H4, to hypervariable region 1 (HVR1) of hepatitis C virus (HCV) were constructed by grafting the variable regions of murine monoclonal antibodies (mAbs) 2P24 and 15H4 to a human IgG1 kappa constant region. Two cAb-producing cell lines were adapted to serum-free media. Both cAb 2P24 and cAb 15H4 cell lines produced 3-5 microg antibodies ml(-1) after 3-5 days culture. cAbs retained binding characteristics similar to those observed in the original mAbs. There was no clear difference in affinity between binding of cAbs and mAbs to seven HVR1 peptides. Mixtures of biotinylated cAbs or mAbs reacted with 32 (86 %) and 31 (84 %) of 37 HVR1 peptides, respectively, but not with non-HVR1 control peptides. HCV from 16 out of 18 (89 %) random HCV-containing plasmas was captured by the mixture of biotinylated cAbs. The capture from IgG-depleted plasmas suggested that cAbs captured mainly free rather than complexed HCV, irrespective of genotype. A mixture of the two cAbs inhibited HCV binding to Molt-4 cells in a dose-dependent manner. These cAbs may be useful for prevention of nosocomial HCV infection and passive immunization to prevent HCV reinfection after liver transplantation.

Prospects for dendritic cell vaccination in persistent infection with hepatitis C virus

Although hepatitis C virus (HCV) is classified in the Hepacivirus genus in the family Flaviviridae, it is unlike most of the other members of this family due to its propensity to cause persistent infections. This persistent infection eventually results in chronic liver disease, cirrhosis and hepatocellular carcinoma in a proportion of infected individuals. It has been difficult to examine correlates of clearance or persistence because most acute phase HCV infections are subclinical or result in symptoms which are non-specific; consequently, acute infections are not generally recognised and patients often present many years later with persistent infection and accompanying chronic liver disease. Nevertheless, seminal studies, performed during the acute phase, have identified a number of factors which are likely to influence the outcome of infection, although it is possible that the mechanism is multifactorial. One of these factors is impairment of dendritic cell function by a mechanism resulting from expression of an HCV protein(s) in these cells. This may be a major factor in the failure of the immune response to expand after HCV infection, leading to persistence. Nevertheless, it may be possible to overcome this defect by autologous transfusion of HCV antigen-loaded, mature dendritic cells and the purpose of this review is to highlight the need and general approaches for developing dendritic cell-based immunotherapy for HCV infection.

Estimating the date of hepatitis C virus infection from patient interviews and antibody tests on stored sera

OBJECTIVES

Studies on the natural history and outcome of chronic hepatitis C virus (HCV) infection differ regarding the proportion of persons who develop serious sequelae over time. Most of these studies use an estimated date of HCV infection based on risk factor data obtained from patient interviews. The date of HCV infection is often estimated using the year of a pre-1992 blood transfusion (BT), or the first year of injecting drug use (IDU). We sought to determine the accuracy of these dates obtained by interview.

METHODS

We compared BT dates reported by patients in a long-term HCV outcome study to dates confirmed in a BT-Lookback project, and also compared the reported first year of IDU to seroconversion dates estimated from HCV tests on historical sera.

RESULTS

Of 28 BT recipients who were interviewed in the HCV outcome study and identified in the Lookback project, 14 (50%; 95% CI: 31-69%) were unaware they had received a BT. Of 25 persons identified in the BT-Lookback project with historical sera available, 9 (36%; 95% CI: 19-57%) had anti-HCV results that did not correlate with their confirmed BT date. Of 216 persons with a history of IDU and historical serum samples available, 66 (31%; 95% CI: 25-37%) had anti-HCV results that did not correlate with their reported first year of IDU.

CONCLUSIONS

Inaccuracies in the length of HCV could occur in outcome studies that rely on patient recall of risk-factor history. Statistical methods that incorporate the uncertainty in assigning infection date are needed.

Epidemiology and risk factors for hepatitis C in Alaska Natives

Large cohorts of persons infected with hepatitis C virus (HCV) that include patients with multiple risk exposures and behaviors have been rarely reported. We herein describe a population-based cohort of 759 Alaska Natives (AN) with HCV who were recruited into a long-term follow-up study. History of injection drug use (IDU) was reported by 60.1% and blood transfusion by 14.0%. The most common genotype was 1a (42.0%), followed by 1b (20.3%), 2b (14.7%), 3a (14.3%), and 2a (7.8%). By multivariable analysis, risk exposures (blood transfusion vs. other; P < 0.01; odds ratio [OR], 2.87; 95% confidence interval [CI], 1.51-5.45) and year of infection (P < 0.01; OR, 3.47; 95% CI, 1.34-8.96) were significantly associated with HCV RNA-positivity. Having an RNA concentration >/=2 million copies/mL was associated with male gender (OR, 1.94) and genotype (P < 0.01 overall; 1a vs. 3a: OR, 1.92; 2b vs. 3a: OR, 3.17) by multivariable analysis. In conclusion, the two principal risk exposures for AN infected with HCV (IDU and blood transfusion) are the same as the overall U.S. population. Persons with a history of blood transfusion were more likely to be HCV RNA positive than those without such history. Higher RNA levels found in males may explain the more severe disease previously reported in this group.