Determinants of Infection Outcome in HCV-Genotype 4

Abstract

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.

Hepatitis C Virus Genotype-4 Epidemiology

Hepatitis C virus (HCV) infection is a global health problem with worldwide prevalence accounting for almost 177 million chronic infections (69). The highest prevalence was reported in less developed countries as follows: Egypt (22%), Pakistan (4.8%), and China (3.2%) (84).

Seven HCV genotypes have been identified so far with multiple subtypes in each genotype class (6,11,45,57,78). This genotype difference is caused by 30–35% difference in nucleotide sites. Within each genotype, 67 confirmed, 20 provisional assigned, and 21 unassigned HCV subtypes are present. Strains belonging to the same subtype are characterized by less than 15% difference of nucleotide sites (89).

Each genotype has its unique geographic distribution, treatment regimen, and response to treatment (31,86). HCV genotype-1 is the most prevalent accounting for 49.1% or total HCV infections worldwide, followed by HCV genotype-3 (17.9%) then genotype-4 (16.8%), genotype-2 (11.0%), genotype-5 (2.0%), the least prevalent is genotype-6 (1.4%), and the remaining 1.8% is mixed genotype infection (30,41,48,69).

HCV is characterized by high genetic diversity which varies across geographical areas. Genotypes 1a, 1b, 2a, and 3a, the so called epidemic subtypes, are the most prevalent especially in high income countries (51,75,90), while the endemic strains are less prevalent and are restricted to certain geographical areas: genotypes 1 and 2 in West Africa, 3 in south Asia, 4 in Central Africa and the Middle East, 5 in Southern Africa, and 6 in South East Asia (75,88,90). HCV-genotype 7 has been isolated in Canada from a Central African immigrant (61).

In Central Africa and the Middle East, HCV genotype 4 (HCV-4) frequencies account for 82.9% in Central sub-Saharan Africa, 65.3% in North Africa and Middle East, and 0.6% in Western sub-Saharan Africa (69). HCV-4 is a very heterogeneous genotype with more reported genetic divergence and subtypes than other genotypes. Eighteen subtypes (4a, 4c, 4d, 4e, 4f, 4g, 4h, 4k, 4l, 4m, 4n, 4o, 4p, 4q, 4r, 4s, 4t, 4u) have been identified in different geographic regions (76). Distinct geographical distribution together with antigenic and biological differences between HCV types reflects long periods of endemic infection in certain geographical regions (90). This difference in subtypes' distribution in different geographic regions helps in tracing the origin of HCV infection in a given region (87).

HCV-4 is continuing epidemic in Egypt, with the highest reported prevalence of HCV infection worldwide. Estimated anti-HCV antibody prevalence among the Egyptian population between 15 and 59 years of age is 10%, and the number of chronically infected Egyptians is 7% (55). HCV infection in Egypt is characterized by low genetic diversity; HCV-4 is the predominant genotype accounting for 93.1% of HCV infections and most of the Egyptian isolates belong to subtype-4a in 80.6% of cases (19,69,77), likely due to the rapid amplification of subtype-4a during the twentieth century as a result of iatrogenic antischistosomal therapy mass campaigns (25). These campaigns resulted in establishment of large reservoir of chronic HCV infection which is responsible for the continued endemic transmission of HCV and the high prevalence of HCV in Egypt (46).

Certain risk factors related to prevailing social and cultural behavior are responsible for maintaining the high rates of HCV-4 transmission in Egypt; medical procedures performed without appropriate cleaning or disinfection of the used equipment, such as circumcision, dentistry practices, wound treatment, and deliveries performed by informal healthcare providers, were identified as important risk factors for HCV transmission in Egypt (20,91,94).

HCV-4 is responsible for 100% of HCV infections in Central and West African countries, such as Liberia, Uganda, Democratic Republic of the Congo (DRC), and Gabon, and for most of HCV infections in Cameroon (38,63,65,69,105,107). In DRC, high diversity of HCV-4 subtypes was observed with subtypes 4c, 4k, 4h, and 4r and new subtypes 4drc and DRC1427 recently identified (36). HCV-4 strains in Central Africa and Cameroon are extremely heterogeneous (63,65,77,87,90,107).

In Middle East countries, HCV prevalence in Saudi Arabia accounts for 3% to 5% with predominance of genotype 4 (60%), subtype 4a (48%) followed by 4d (39%). HCV-4 accounts for 36–46% of HCV infections in Lebanon, 59% in Syria, 52.9% in Iraq, 54.2% in Kuwait, and 64.1% in Palestine, while 27% of HCV-infected hemodialysis patients in Jordan have HCV-4 (3,5,8,69,83).

HCV-4 has become increasingly prevalent in some southern European countries on the Mediterranean Sea particularly Italy, France, Greece, and Spain, with prevalence rates of 10% to 24% reported in some areas, and genotypes 4d and 4a are the major subtypes reported in southern Europe (4,24,42,64).

Natural Course of HCV Genotype-4 Infection

All HCV genotypes have the same natural history (38). Acute HCV infection develops in a period of 6 to 10 weeks after exposure to the virus, and most infected individuals (∼80%) are asymptomatic at the acute stage and are unaware of being infected (53,65). Thus, HCV has been referred to as the “silent epidemic” (112). Unfortunately, around 70–90% of infected people fail to clear the virus during the acute phase of the disease becoming chronic HCV carriers (18,106).

Chronic HCV infection is a slowly progressing lifelong infection that may remain asymptomatic in 60–80% of patients up to 20 years until evidence of liver failure becomes clinically apparent (18,53). Chronic persistent nature of the disease is the cause of the serious complications associated with HCV infection (32). Liver cirrhosis develops in 5–20% of chronic HCV patients and is complicated by hepatocellular carcinoma (HCC) in 1–5% of persons with chronic hepatitis C (32).

Certain factors are identified to influence hepatic fibrosis progression; geographic and environmental factors (50), host factors as TGF B1 phenotype or PNPLA-3 are correlated with fibrosis progression rate (111), genetic determinants that influence HCV specific cellular immunity like HLA expression probably guide the inflammatory response (33).

More rapid fibrosis progression is seen in male patients older than 40–55 years (92), old age at time of infection acquisition is associated with higher rates of fibrosis progression irrespective of duration of the infection, and in HCV-4 infection male patients were 2.9 times more liable to have progressive liver disease and HCC development (14,66,73).

Alcohol intake enhances HCV replication, disease progression, liver injury, and progression to cirrhosis (12,29,32) through immune dysregulation, pro-inflammatory and profibrotic cytokine stimulation, oxidative stress, and steatosis (80). Tobacco use was identified as an independent risk factor for fibrosis and has been linked to HCC induced by chronic hepatitis (58,68).

Mode of HCV transmission has been suggested to affect disease progression; chronic HCV infection caused by blood transfusions was associated with rapidly progressive disease, compared to infection caused by intravenous drug abuse and that may be related to higher HCV loads transmitted during blood transfusion (15,44,98).

Concomitant schistosomiasis in the Egyptian patients might explain the higher fibrosis scores in Egyptian patients; previous studies showed that patients with chronic HCV-4 and schistosomiasis coinfection have an accelerated rate of hepatic fibrosis progression (39,40).

HIV/HCV coinfection increases the rate of hepatic fibrosis progression by 3-folds leading to more advanced liver fibrosis as HIV induced immunologic alterations are supposed to promote hepatic fibrosis (27,99). Patients with HBV/HCV coinfection are at higher risk of progressive and decompensated liver disease and HCC owing to the synergistic carcinogenic interaction exerted by both viruses (16,56).

Insulin resistance measured by the homeostasis model assessment index (HOMA-IR) is reported as independent factor associated with severity of fibrosis and is more prevalent in genotypes 1 and 4 than in genotypes 2 and 3 HCV infections (35,59,60). The relation of insulin resistance to hepatic fibrosis progression was explained by the stimulatory effect of hyperinsulinemia and hyperglycemia on hepatic stellate cells leading to activation of connective tissue growth factor and accumulation of extracellular matrix proteins, stimulation of inflammation, and steatosis (34,96).

HCC risk is 17-folds higher in HCV-infected patients compared to HCV-negative subjects, and the risk is directly related to cirrhosis or advanced fibrosis (16,22). The mechanisms by which HCV may lead to HCC may be related to repeated cycles of hepatocyte destruction and regeneration over many years eventually causing neoplastic transformation and progression to HCC (104). Some studies stated that HCV-4 infection is associated with greater risk for hepatocellular carcinoma than other HCV genotypes (23,109).

In Egypt, HCC is the second cause of cancer and cancer mortality among men and the fourth in women. Egypt National Cancer Institute Registry reported that the incidence rate of HCC among males was seven times greater than Israeli Jews, having the next highest rate, and thrice more than that reported in the United States (26,62). More than 84% of Egyptian patients with HCC are positive for HCV-4 (49). High alpha-fetoprotein and serum aspartate aminotransferase levels, male gender, and presence of cirrhosis have been identified as risk factors associated with HCC development in Egyptian patients (66).

Hepatitis C Genotype-4 Treatment Options

The goal of chronic HCV treatment is to reduce hepatic inflammation and prevent fibrosis progression, cirrhosis, and HCC through the eradication of the virus in chronically infected patients, thereby decreasing infectivity and controlling disease spread (106).

The indicator of effective treatment is a sustained viral response (SVR), defined by the absence of detectable HCV RNA in the serum (by a qualitative HCV RNA assay with lower limit of detection of 50 IU/mL or less) at 24 weeks after the end of treatment (18,74). In 2011, the FDA accepted SVR-12 (HCV RNA negativity 12 weeks after end of treatment) as end point for future trials because HCV relapse usually occurs within the first 12 weeks after the end of treatment. Patients with SVR will remain HCV RNA negative for at least 5 years after stopping therapy and experience a long-term biochemical and histological outcome with a decrease in total inflammatory activity, a decrease in the reversible components of fibrosis, and reduction of HCV-related hepatocellular carcinoma (100,101). However, in rare cases, virologic relapses may occur (47,52,93).

Until recently, pegylated interferon (PEG-IFN) combined with daily oral ribavirin (RBV) was the only drug used for treatment of HCV-4. However, the response rate was not satisfactory. Around 50% of patients responded to IFN by normalizing alanine aminotransferase at the end of therapy, half of them failed to achieve SVR, and minority of patients had persistent disappearance of HCV RNA from serum (32,74).

Since the introduction of direct acting antiviral (DAA) agents in HCV treatment, better treatment efficacy has been achieved. DAA agents act directly on HCV at various points in the viral life cycle, by targeting specific nonstructural proteins of the virus and disrupting viral replication.

There are four classes of DAA agents with different targets and mechanism of action: nonstructural proteins 3/4A (NS3/4A) protease inhibitors (PIs), NS5B nucleoside polymerase inhibitors (NPIs), NS5B non-nucleoside polymerase inhibitors (NNPIs), and NS5A inhibitors (72). NS3/4A PIs block the catalytic site or theNS3/NS4A interaction thus interrupting posttranslational processing (70). NS5B NPIs mimic the natural substrates of the polymerase and become incorporated into the growing RNA chain and act as chain terminator preventing virus replication (67). NS5B NNPIs bind directly to the enzyme rendering it ineffective by inducing conformational change in the enzyme structure (67). NS5A inhibitors function by deregulating the interaction between NS5A and HCV replication sites (95).

Owing to the high rate of HCV replication and mutation, resistance to DAA agents occurs due to mutations that lead to changes in the structure of the viral enzymes on which DAA drugs act (82). Multidrug approach is required that includes DAA agents targeting different mechanisms to overcome drug resistance (37).

Association for the Study of Liver Diseases (AASLD) and the Infectious Diseases Society of America (IDSA) in collaboration with the International Antiviral Society–USA (IAS-USA) for treatment of HCV-4 infection recommend the use of DAA agent combination either alone or in addition to RBV in HCV-4 patients. Recommended drug combinations depend on whether patients are treatment naive or treatment experienced and according to the state of liver cirrhosis whether compensated or decompensated (1).

DAA treatment options for HCV-4 are shown in table 1. Treatment recommendations are based on several multicentric clinical trial results carried out on HCV-4 patients in several countries. In the SYNERGY trial, sofosbuvir/ledipasvir for a duration of 12 weeks was evaluated in 21 HCV-4 infected patients; 20/21 patients completed treatment and achieved 100% SVR12 (43).

Table 1.

American Association for the Study of Liver Diseases and the Infectious Diseases Society of America Recommendations for Treating HCV-4

Treatment-naive patients without/with compensated liver cirrhosis (recommended)	All patients who have decompensated liver cirrhosis (recommended)	PEG-IFN/RBV treatment experienced patients without cirrhosis (recommended)	PEG-IFN/RBV treatment experienced patients with compensated cirrhosis (recommended)	PEG-IFN/RBV treatment experienced patients with compensated cirrhosis (alternative)
Daily fixed-dose combination of paritaprevir (150 mg)/ritonavir (100 mg)/ombitasvir (25 mg) and weight-based RBV for 12 weeks Daily fixed-dose combination of sofosbuvir (400 mg)/velpatasvir (100 mg) for 12 weeks Daily fixed dose combination of elbasvir (50 mg)/grazoprevir (100 mg) for 12 weeks Daily fixed dose combination of ledipasvir (90 mg)/sofosbuvir (400 mg) for 12 weeks	Patients with HCV infection who have decompensated cirrhosis (moderate or severe hepatic impairment); Child Turcotte Pugh (class B or C) should be referred to a medical practitioner with expertise in that condition (ideally in a liver transplant center).	Daily fixed-dose combination of paritaprevir (150 mg)/ritonavir (100 mg)/ombitasvir (25 mg) and weight-based RBV for 12 weeks for patients in whom prior treatment with PEG-IFN/RBV has failed. Daily fixed-dose combination of sofosbuvir (400 mg)/velpatasvir (100 mg) for 12 weeks for patients, in whom prior treatment with PEG-IFN/RBV has failed. Daily fixed-dose combination of elbasvir (50 mg)/grazoprevir (100 mg) for 12 patients who experienced virologic relapse after prior PEG-IFN/RBV therapy. Patients with prior on-treatment virologic failure (failure to suppress or breakthrough) while on PEG-IFN/RBV should be treated for 16 weeks and have weight-based RBV added to the treatment regimen. Daily fixed-dose combination of ledipasvir (90 mg)/sofosbuvir (400 mg) for 12 weeks for patients in whom prior treatment with PEG-IFN/RBV treatment has failed.	Daily fixed-dose combination of paritaprevir (150 mg)/ritonavir (100 mg)/ombitasvir (25 mg) and weight-based RBV for 12 weeks for patients in whom prior treatment with PEG-IFN/RBV has failed. Daily fixed-dose combination of sofosbuvir (400 mg)/velpatasvir (100 mg) for 12 weeks for patients in whom prior treatment with PEG-IFN/RBV has failed. Daily fixed-dose combination of elbasvir (50 mg)/grazoprevir (100 mg) for 12 weeks for patients who experienced virologic relapse after prior PEG-IFN/RBV therapy. Patients with prior on-treatment virologic failure (failure to suppress or breakthrough) while on PEG-IFN/RBV should be treated for 16 weeks and have weight-based RBV added to the treatment regimen. Daily ledipasvir (90 mg)/sofosbuvir (400 mg) and weight-based RBV for 12 weeks in whom prior treatment with PEG-IFN/RBV has failed and who are eligible for RBV.	Daily fixed-dose combination of ledipasvir (90 mg)/sofosbuvir (400 mg) for 24 weeks for patients in whom prior treatment with PEG-IFN/RBV has failed.

HCV-4, HCV genotype 4; PEG-IFN, pegylated interferon; RBV, ribavirin.

SOLAR-1 and SOLAR-2 trials studied the use of sofosbuvir/ledipasvir in patients with decompensated liver disease or posttransplantation. In the SOLAR-1 study, 5 HCV-4 infected patients were studied among 331 patients of other genotypes. In SOLAR-2, 32 HCV-4 infected patients were studied (divided into group 1: posttransplant patients without cirrhosis or with compensated cirrhosis and group 2: pre- or posttransplant patients with decompensated cirrhosis). Treatment duration was either for 12 or 24 weeks +/−RBV. Group 1 achieved SVR12 in 91% of patients treated for 12 weeks, and SVR12 was 100% in patients treated for 24 weeks. In group 2, SVR12 was 57% in patients with 12-week treatment duration and 86% in patients treated for 24 weeks (10).

Another study included 44 patients (22 treatment naive and 22 IFN-experienced patients) infected with HCV-4 infection that were treated with sofosbuvir/ledipasvir. Excellent SVR12 and SVR24 rates were achieved reaching 95.5% in treatment naive patients and 90.9% in IFN-experienced patients (2).

In the French ANRS CO22 HEPATHER study, the use of sofosbuvir and daclatasvir plus RBV for 12 weeks reached 100% SVR in HCV-4 infected patients (13).

The use of sofosbuvir with simeprevir for 12 weeks was evaluated in a large multicenter observational study in Egypt that included 583 patients with HCV-4 infection. Out of a total of 583 patients, 342 (59%) were treatment naive. Out of a total of 583 patients, 558 (95.7%) achieved SVR12 (21). In another study conducted on 50 Egyptian patients, 20/50 were relapsers on a previous treatment for HCV. Sofosbuvir and simeprevir treatment achieved SVR12 in 100% of patients, while SVR24 was 96.6% in treatment naive patients, 100% in relapser noncirrhotic patients, and 90% in relapser cirrhotic patients (28). Other studies included HCV-4 Egyptian patients treated with sofosbuvir plus weight-based RBV (1,000 mg [<75 kg] to 1,200 mg [≥75 kg]). SVR12 of treatment-naive patients treated for 12 weeks and 24 weeks was 79% (11/14) and 100% (14/14), respectively (79), and was 84% (21/25) and 92% (22/24), respectively (17).

The use of paritaprevir/ritonavir/ombitasvir (PrO) was evaluated in multiple clinical trials. In PEARL-I, patients received daily fixed-dose combination of PrO with or without weight-based RBV for 12 weeks. SVR12 rates were 100% (42/42) in the group receiving RBV and 90.9% (40/44) in the group not receiving RBV (71). In AGATE-I trial, PrO+RBV treatment for 16 weeks was assessed in HCV-4 treatment-experienced patients with compensated cirrhosis and SVR12 was 100% (7). AGATE-II trial evaluated treatment duration of 12 weeks versus 24 weeks in 160 HCV-4 infected Egyptian patients. SVR 12 was higher in patients who received treatment for 12 weeks and achieved 94–97% SVR12 compared to 93% in patients who received treatment for 24 weeks (102).

In the C-EDGE trial, elbasvir/grazoprevir for 12 weeks achieved 100% SVR12 rates (110).

Liver transplantation is indicated in patients with life-threatening cirrhosis who manifest clinically evident end-stage liver disease or those who developed HCC (101). End-stage liver disease secondary to HCV infection is the major indication for liver transplantation worldwide (97).

After transplantation, however, liver grafts are rapidly reinfected and the risk of progression to cirrhosis reappears (81); a higher viral load and the presence of antibody to hepatitis B core antigen could be risk factors for reinfection (54); reinfection can be also related to persistence of HCV-RNA in the peripheral blood mononuclear cells despite clearance from serum (9,108).

In a study by Wali et al. (103), HCV-4 was associated with significantly greater fibrosis progression rates than nongenotype 4, and the 5-year cumulative risk for development of severe fibrosis was found to be higher in patients with HCV-4 than in nongenotype 4 patients (85% vs. 24%). In addition, confluent necrosis was observed in more than 50% of HCV-4 patients and in less than 25% of nongenotype 4 patients (103). In a study on Egyptian patients, HCV clinical recurrence occurred in 31% of patients and was mostly mild where most of the patients had fibrosis score less than F2 (97).

Conclusion

HCV-4 previously considered difficult to treat virus is now a potentially curable disease. Previously, treatment was limited to the use of the suboptimal regimen of interferon plus RBV achieving moderate efficacy with numerous side effects. In the past few years, the introduction of DAA agents showed promising treatment outcomes with high rates of SVR and few side effects. This improvement in treatment modalities is owed to the understanding of different aspects characterizing HCV-4. Several DAA agents proved great efficacy in HCV-4 treatment; however, the choice of the preferred drug combination relies on several aspects, including patients' clinical condition, tolerability, drug availability, treatment duration, and cost especially in resource-limited countries where HCV-4 is prevalent.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

References

AASLD-IDSA. Recommendations for testing, managing, and treating hepatitis C. www.hcvguidelines.org (Accessed April 29, 2017 ).

Abergel

, Asselah

, Metivier

, et al. Ledipasvir-sofosbuvir in patients with hepatitis C virus genotype 5 infection: an open-label, multicentre, single-arm, phase 2 study. Lancet Infect Dis, 2016; 16:459–464.

Al Ashgar

, Khan

, Al-Ahdal

, et al. Hepatitis C genotype 4: genotypic diversity, epidemiological profile, and clinical relevance of subtypes in Saudi Arabia. Saudi J Gastroenterol, 2013; 19:28–33.

Ansaldi

, Bruzzone

, Salamaso

, et al. Different seroprelavence and molecular epidemiology pattern of hepatitis C virus infection in Italy. J Med Virol, 2005; 76: 327–332.

Antaki

, Haddad

, Kebbewar

, et al. The unexpected discovery of a focus of hepatitis C virus genotype 5 in a Syrian province. Epidemiol Infect, 2008; 137:79–84.

Antiretroviral Therapy Cohort Collaboration. Causes of death in HIV-1-infected patients treated with antiretroviral therapy, 1996–2006: collaborative analysis of 13 HIV cohort studies. Clin Infect Dis, 2010; 50:1387–1396.

Asselah

, Hassanien

, Qaqish

, et al. P1345: a randomized, open-label study to evaluate efficacy and safety of ombitasvir/paritaprevir/ritonavir coadministered with ribavirin in adults with genotype 4 chronic hepatitis C infection and cirrhosis. J Hepatol, 2015; 62:S861.

Bdour

. Hepatitis C virus infection in Jordanian hemodialysis units: serological diagnosis and genotyping. J Med Microbiol, 2002; 51:700–704.

Chang

, Young

, Yang

, et al. Hepatitis C virus RNA in peripheral blood mononuclear cells: comparing acute and chronic hepatitis C virus infection. Hepatology, 1996; 23:977–981.

10.

Charlton

, Everson

, Flamm

, et al. Ledipasvir and sofosbuvir plus ribavirin for treatment of HCV infection in patients with advanced liver disease. Gastroenterology, 2015; 149:649–659.

11.

Cooke

, Lemoine

, Thursz

, et al. Viral hepatitis and the Global Burden of Disease: a need to regroup. J Viral Hepat, 2013; 20:600–601.

12.

Corrao

, and Arico

. Independent and combined action of hepatitis C virus infection and alcohol consumption on the risk of symptomatic liver cirrhosis. Hepatology, 1998; 27:914–919.

13.

De Ledinghen

, Fontaine

, Dorival

, et al. Safety and efficacy of sofosbuvir containing regimens in the French observational cohort ANRS CO22 HEPATHER. J Hepatol, 2015; 62(S2):631–632.

14.

de Torres

, and Poynard

. Risk factors for liver fibrosis progression in patients with chronic hepatitis C. Ann Hepatol, 2003; 2:5–11.

15.

Di Bisceglie

, Goodman

, Ishak

, et al. Long-term clinical and histopathological follow-up of chronic post transfusion hepatitis. Hepatology, 1991; 14:969–974.

16.

Donato

, Boffetta

, and Puoti

. A meta-analysis of epidemiological studies on the combined effect of hepatitis B and C virus infections in causing hepatocellular carcinoma. Int J Cancer, 1998; 75:347–354.

17.

Doss

, Shiha

, Hassany

, et al. Sofosbuvir plus ribavirin for treating Egyptian patients with hepatitis C genotype 4. J Hepatol, 2015; 63:581–585.

18.

EASL International Consensus Conference on hepatitis

. Paris, 26-27 February 1999. Consensus statement. J Hepatol. 1999; 31 Suppl 1:3–8.

19.

Elkady

, Tanaka

, Kurbanov

, et al. Genetic variability of hepatitis C virus in South Egypt and its possible clinical implication. J Med Virol, 2009; 81:1015–1023.

20.

El Katsha

, Labeeb

, Watts

, et al. Informal health providers and the transmission of hepatitis C virus: pilot study in two Egyptian villages. East Mediterr Health J, 2006; 12:758–767.

21.

El-Khayat

, Fouad

, Maher

, et al. Efficacy and safety of sofosbuvir plus simeprevir therapy in Egyptian patients with chronic hepatitis C: a real-world experience. Gut, 2016 [Epub ahead of print]; DOI: 10.1136/gutjnl-2016-312012.

22.

El-Serag

. Hepatocellular carcinoma and hepatitis C in the United States. Hepatology, 2002; 36:S74–S83.

23.

Ezzat

, Abdel-Hamid

, Eissa

, et al. Associations of pesticides, HCV, HBV and hepatocellular carcinoma in Egypt. Int J Hyg Environ Health, 2005; 208:32939.

24.

Fernandez-Arcas

, Lopez-Siles

, Trapero

, et al. High prevalence of hepatitis C virus subtypes 4c and 4d in Malaga (Spain): phylogenetic and epidemiological analyses. J Med Virol, 2006; 78:1429–1435.

25.

Frank

, Mohamed

, Strickland

, et al. The role of parenteral antischistosomal therapy in the spread of hepatitis C virus in Egypt. Lancet, 2000; 355:887–891.

26.

Freedman

, Edwards

, Ries

LAG

, et al. Cancer incidence in four member countries (Cyprus, Egypt, Israel, and Jordan) of the middle east cancer consortium (MECC) compared with US SEER. Bethesda, MD: National Cancer Institute, NIH Pub. No. 06-5873, 2006.

27.

Graham

, Baden

, Yu

, et al. Influence of human immunodeficiency virus infection on the course of hepatitis C virus infection: a meta-analysis. Clin Infect Dis, 2001; 33:562–569.

28.

Hanno

, Elwazzan

, Ibrahim

, et al. A real life study on treatment of Egyptian patients with HCV genotype IV with simeprevir and sofosbuvir. Health, 2016; 8:780–786.

29.

Harris

, Gonin

, Alter

, et al. The relationship of acute transfusion associated hepatitis to the development of cirrhosis in the presence of alcohol abuse. Ann Intern Med, 2001; 134:120–124.

30.

Hatzakis

, Chulanov

, Gadano

, et al. The present and future disease burden of hepatitis C virus (HCV) infections with today's treatment paradigm—volume 2. J Viral Hepat, 2015; 22 Suppl 1:26–45.

31.

Hnatyszyn

. Chronic hepatitis C and genotyping: the clinical significance of determining HCV genotypes. Antiviral Ther, 2005; 10:1–11.

32.

Houghton

. Hepatitis C viruses. In: Fields

, Knipe

, and Howley

, eds. Fields Virology. 3rd ed. Philadelphia, PA: Lippincott-Raven, 1996:1035–1058.

33.

Hraber

, Kuiken

, and Yusim

. Evidence for human leukocyte antigen heterozygote advantage against hepatitis C virus infection. Hepatology, 2007; 46:1713–1721.

34.

Hsu

, Liu

, et al. Association of metabolic profiles with hepatic fibrosis in chronic hepatitis C patients with genotype 1 or 2 infection. J Gastroenterol Hepatol, 2010; 25:970–977.

35.

Hui

, Sud

, Farrell

, et al. Insulin resistance is associated with chronic hepatitis C virus infection and fibrosis progression. Gastroenterology, 2003; 125:1695–1704.

36.

Iles

, Raghwani

, Harrison

, et al. Phylogeography and epidemic history of hepatitis C virus genotype 4 in Africa. Virology, 2014; 464–465:233–243.

37.

Jazwinski

, and Muir

. Direct-acting antiviral medications for chronic hepatitis C virus infection. Gastroenterol Hepatol, 2011; 7:154–162.

38.

Kamal

, and Nasser

. Hepatitis C genotype 4: what we know and what we don't yet know. Hepatology, 2008; 47:1371–1383.

39.

Kamal

, Graham

, He

, et al. Kinetics of intrahepatic hepatitis C virus (HCV)-specific CD4+ T cell responses in HCV and Schistosoma mansoni coinfection: relation to progression of liver fibrosis. J Infect Dis, 2004; 189:1140–1150.

40.

Kamal

, Turner

, He

, et al. Progression of fibrosis in hepatitis C with and without schistosomiasis: correlation with serum markers of fibrosis. Hepatology, 2006; 43:771–779.

41.

Karoney

, and Siika

. Hepatitis C virus (HCV) infection in Africa: a review. Pan Afr Med J, 2013; 14:44.

42.

Katsoulidou

, Sypsa

, Tassopoulos

, et al. Molecular epidemiology of hepatitis C virus (HCV) in Greece: temporal trends in HCV genotype-specific incidence and molecular characterization of genotype 4 isolates. J Viral Hepat, 2006; 13:19–27.

43.

Kohli

, Kapoor

, Sims

, et al. Ledipasvir and sofosbuvir for hepatitis C genotype 4: a proof-of-concept, single-centre, open-label phase 2a cohort study. Lancet Infect Dis, 2015; 15:1049–1054.

44.

Koretz

, Abbey

, Coleman

, et al. Non-A, non-B post-transfusion hepatitis. Looking back in the second decade. Ann Intern Med, 1993; 119:110–115.

45.

Lauer

, and Walker

. Hepatitis C virus infection. N Engl J Med, 2001; 345:41–52.

46.

Lavanchy

, and McMahon

. Worldwide prevalence and prevention of hepatitis C. In: Liang

, and Hoofnagle

, eds. Hepatitis C. San Diego, CA: Academic Press, 2000:185–202.

47.

Lawitz

, Poordad

, Kowdley

, et al. 12-week interferon-free regimen of ABT-450/R, ABT-072, and ribavirin was well tolerated and achieved sustained virologic response in 91% treatment-naive HCVIL28B-CC genotype-1-infected subjects. J Hepatol, 2013; 59:18–23.

48.

Lawitz

, Poordad

, Pang

, et al. Sofosbuvir and ledipasvir fixed-dose combination with and without ribavirin in treatment-naive and previously treated patients with genotype 1 hepatitis C virus infection (LONESTAR): an open-label, randomised, phase 2 trial. Lancet, 2014; 383:515–523.

49.

Lehman

, and Wilson

. Epidemiology of hepatitis viruses among hepatocellular carcinoma cases and healthy people in Egypt: a systematic review and meta analysis. Int J Cancer, 2009; 124:690–697.

50.

Lim

, and Kim

. The global impact of hepatic fibrosis and end-stage liver disease. Clin Liver Dis, 2008; 12:733–746.

51.

Magiorkinis

, Magiorkinis

, Paraskevis

, et al. The global spread of hepatitis C virus 1a and 1b: a phylodynamic and phylogeographic analysis. PLoS Med, 2009; 6:e1000198.

52.

Manns

, Pockros

, Norkrans

, et al. Long-term clearance of hepatitis C virus following interferon α-2b or peginterferon α-2b, alone or in combination with ribavirin. J Viral Hepat, 2013; 20:524–529.

53.

Mast

, Alter

, and Margolis

. Strategies to prevent and control hepatitis B and C virus infections: a global perspective. Vaccine, 1999; 17:1730–1733.

54.

Mehrez

, Farrag

, El Sahhar

, et al. Pattern of recurrent hepatitis C in deceased vs living donor liver transplantation: an Egyptian experience. Euroasian J Hepato-Gastroenterol, 2013; 3:111–116.

55.

Ministry of Health and Population [Egypt], El-Zanaty and Associates [Egypt], and International. Egypt Demographic and Health Survey 2014. Cairo, Egypt and Rockville, MD: Ministry of Health and Population and ICF International, 2015.

56.

Mohamed

, al Karawi

, and Mesa

. Dual infection with hepatitis C and B viruses: clinical and histological study in Saudi patients. Hepatogastroenterology, 1997; 44:1404–1406.

57.

Mohd Hanafiah

, Groeger

, Flaxman

, et al. Global epidemiology of hepatitis C virus infection: new estimates of age-specific antibody to HCV seroprevalence. Hepatology, 2013; 57:1333–1342.

58.

Mori

, Hara

, Wada

, et al. Prospective study of hepatitis B and C viral infections, cigarette smoking, alcohol consumption, and other factors associated with hepatocellular carcinoma risk in Japan. Am J Epidemiol, 2000; 151:131–139.

59.

Moucari

, Asselah

, Cazals-Hatem

, et al. Insulin resistance in chronic hepatitis C: association with genotypes 1 and 4, serum HCV RNA level, and liver fibrosis. Gastroenterology, 2008; 134:416–423.

60.

Moucari

, Ripault

, Martinot-Peignoux

, et al. Insulin resistance and geographical origin: major predictors of liver fibrosis and response to peginterferon and ribavirin in HCV-4. Gut, 2009; 59:1662–1669.

61.

Murphy

, Willems

, Deschenes

, et al. Use of sequence analysis of the NS5B region for routine genotyping of hepatitis C virus with reference to C/E1 and 5′ untranslated region sequences. J Clin Microbiol, 2007; 45:1102–1112.

62.

National Cancer Registry of Egypt. Magnitude of hepatocellular carcinoma in Egypt. 2010. www.nci.edu.eg

63.

Ndjomou

, Pybus

, and Matz

. Phylogenetic analysis of hepatitis C virus isolates indicates a unique pattern of endemic infection in Cameroon. J Gen Virol, 2003; 84:2333–2341.

64.

Nicot

, Legrand-Abravanel

, Sandres-Saune

, et al. Heterogeneity of hepatitis C virus genotype 4 strains circulating in south-western France. J Gen Virol, 2005; 86:107–114.

65.

Njouom

, Nerrienet

, Dubois

, et al. The hepatitis C virus epidemic in Cameroon: genetic evidence for rapid transmission between 1920 and 1960. Infect Genet Evol, 2007; 7:361–367.

66.

Omran

, Awad

, Mabrouk

, et al. Application of data mining techniques to explore predictors of HCC in Egyptian patients with HCV-related chronic liver disease. Asian Pac J Cancer Prev, 2015; 16:381–385.

67.

Pawlotsky

, Chevaliez

, McHutchison

. The hepatitis C virus life cycle as a target for new antiviral therapies. Gastroenterology, 2007; 132:1979–1998.

68.

Pessione

, Ramond

, Njapoum

, et al. Cigarette smoking and hepatic lesions in patients with chronic hepatitis C. Hepatology, 2001; 34:121–125.

69.

Petruzziello

, Marigliano

, Loquercio

, et al. Global epidemiology of hepatitis C virus infection: an up-date of the distribution and circulation of hepatitis C virus genotypes. World J Gastroenterol, 2016; 22:7824–7840.

70.

Pockros

. New direct-acting antivirals in the development for hepatitis C virus infection. Therap Adv Gastroenterol, 2010; 3:191–202.

71.

Pol

, Reddy

, Hezode

, et al. Interferon-free regimens of ombitasvir and ABT 450/r with or without ribavirin in patients with HCV genotype 4 infection: PEARL-I study results. [Abstract 1928] 65th Annual Meeting of the American Association for the Study of Liver Diseases (AASLD); Boston, MA. November 7–11, 2014.

72.

Poordad

, and Dieterich

. Treating hepatitis C: current standard of care and emerging direct-acting antiviral agents. J Viral Hepat, 2012; 19:449–464.

73.

Pradat

, Voirin

, Tillmann

, et al. Progression to cirrhosis in hepatitis C patients: an age-dependent process. Liver Int, 2007; 27:335–339.

74.

Proceedings of the International Workshop on epidemiology, diagnosis and management of hepatitis C infection. Med Community, 1996; 6–7:1–32.

75.

Pybus

, Barnes

, Taggart

, et al. Genetic history of hepatitis C virus in East Asia. J Virol, 2009; 83:1071–1082.

76.

Rapicetta

, Argentini

, Dettori

, et al. Molecular heterogeneity and new subtypes of HCVgenotype 4. Res Virol, 1998; 149:293–297.

77.

Ray

, Arthur

, Carella

, et al. Genetic epidemiology of hepatitis C virus throughout Egypt. J Infect Dis, 2000; 182:698–707.

78.

Razavi

, Elkhoury

, Elbasha

, et al. Chronic hepatitis C virus (HCV) disease burden and cost in the United States. Hepatology, 2013; 57:2164–2170.

79.

Ruane

, Ain

, Stryker

, et al. Sofosbuvir plus ribavirin for the treatment of chronic genotype 4 hepatitis C virus infection in patients of Egyptian ancestry. J Hepatol, 2015; 62:1040–1046.

80.

Safdar

, and Schiff

. Alcohol and hepatitis C. Semin Liver Dis, 2004; 24:305–315.

81.

Samuel

, and Feray

. Recurrence of hepatitis C virus infection after liver transplantation. J Hepatol, 1999; 31:217–221.

82.

Sentandreu

, Jiménez-Hernández

, Torres-Puente

, et al. Evidence of recombination in intrapatient populations of hepatitis C virus. PLoS One, 2008; 3:e3239.

83.

Sharara

, Ramia

, Ramlawi

, et al. Genotypes of hepatitis C virus (HCV) among Lebanese patients: comparison of data with that from other middle Eastern countries. Epidemiol Infect, 2007; 135:427–432.

84.

Shepard

, Finelli

, and Alter

. Global epidemiology of hepatitis C virus infection. Lancet Infect Dis, 2005; 5:558–567.

85.

Shobokshi

, Serebour

, Skakni

, et al. Hepatitis C genotypes and subtypes in Saudi Arabia. J Med Virol, 1999; 58:44–48.

86.

Simmonds

, Alberti

, Alter

, et al. A proposed system for the nomenclature of hepatitis C viral genotypes. Hepatology, 1994; 19:1321–1324.

87.

Simmonds

. Genetic diversity and evolution of hepatitis C virus—15 years on. J Gen Virol, 2004; 85(Pt 11):3173–3188.

88.

Simmonds

. The origin and evolution of hepatitis viruses in humans. J Gen Virol, 2001; 82 (Pt 4):693–712.

89.

Smith

, Bukh

, Kuiken

, et al. Expanded classification of hepatitis C virus into 7 genotypes and 67 subtypes: updated criteria and genotype assignment Web resource. Hepatology, 2014; 59:318–327.

90.

Smith

, Pathirana

, Davidson

, et al. The origin of hepatitis C virus genotypes. J Gen Virol, 1997; 78 (Pt 2):321–328.

91.

Stoszek

, Abdel-Hamid

, Narooz

, et al. Prevalence of and risk factors for hepatitis C in rural pregnant Egyptian women. Trans R Soc Trop Med Hyg, 2006; 100:102–107.

92.

Svirtlih

, Jevtovic

, Simonovic

, et al. Older age at the time of liver biopsy is the important risk factor for advanced fibrosis in patients with chronic hepatitis C. Hepatogastroenterology, 2007; 54:2324–2327.

93.

Swain

, Lai

M-Y

, Shiffman

, et al. A sustained virologic response is durable in patients with chronic hepatitis C treated with peginterferon alfa-2a and ribavirin. Gastroenterology, 2010; 139:1593–1601.

94.

Talaat

, Kandeel

, El-Shoubary

, et al. Occupational exposure to needlestick injuries and hepatitis B vaccination coverage among health care workers in Egypt. Am J Infect Control, 2003; 31:469–474.

95.

Targett-Adams

, Graham

, Middleton

, et al. Small molecules targeting hepatitis C virus-encoded NS5A cause subcellular redistribution of their target: insights into compound modes of action. J Virol, 2011; 85:6353–6368.

96.

Taura

, Ichikawa

, Hamasaki

, et al. Association between liver fibrosis and insulin sensitivity in chronic hepatitis C patients. Am J Gastroenterol, 2006; 101:2752–2759.

97.

Terrault

, and Berenguer

. Treating hepatitis C infection in liver transplant recipients. Liver Transpl, 2006; 12:1192–1204.

98.

Tong

, el-Farra

, Reikes

, et al. Clinical outcomes after transfusion associated hepatitis C. N Engl J Med, 1995; 332:1463–1466.

99.

Tuyama

, Hong

, Saiman

, et al. Human immunodeficiency virus (HIV-1) infects human hepatic stellate cells and promotes collagen I and monocyte chemoattractant protein-1 expression: implications for the pathogenesis of HIV/HCV virus induced liver fibrosis. Hepatology, 2010; 52:612–622.

100.

van der Meer

, Veldt

, Feld

, et al. Association between sustained virological response and all-cause mortality among patients with chronic hepatitis C and advanced hepatic fibrosis. JAMA, 2012; 308:2584–2593.

101.

Veldt

, Heathcote

, Wedemeyer

, et al. Sustained virologic response and clinical outcomes in patients with chronic hepatitis C and advanced fibrosis. Ann Intern Med, 2007; 147:677–684.

102.

Waked

, Shiha

, Qaqish

, et al. Ombitasvir, paritaprevir and ritonavir plus ribavirin for chronic hepatitis C virus genotype 4 infection in Egyptian patients with or without compensated cirrhosis (AGATE-II) a multicentre, phase 3, partly randomized open-label trial. Lancet, 2016; 1:36–44.

103.

Wali

, Heydtmann

, Harrison

, et al. Outcome of liver transplantation for patients infected by hepatitis C, including those infected by genotype 4. Liver Transpl, 2003; 9:796804.

104.

Walker

. Hepatitis C virus. In: Ahmed

, and Chen

, eds. Persistent Viral Infections. Chichester, United Kingdom: Wiley, 1999:93–115.

105.

Wansbrough-Jones

, Frimpong

, Cant

, et al. Prevalence and genotype of hepatitis C virus infection in pregnant women and blood donors in Ghana. Trans R Soc Tropical Med Hyg, 1998; 92:496–499.

106.

World Health Organization. Global surveillance and control of hepatitis C. Report of a WHO Consultation organized in Collaboration with the Viral Hepatitis Prevention Board, Antwerp, Belgium. J Viral Hepatol, 1999; 6:35–47.

107.

L-Z

, Larzul

, Delaporte

, et al. Hepatitis C virus genotype 4 is highly prevalent in central Africa (Gabon). J Gen Virol, 1994; 75:2393–2398.

108.

Zayed

, Rushdy

, and Saleh

. Detection of HCV RNA in the peripheral blood mononuclear cells of serum HCV RNA-negative Egyptian patients under interferon treatment. Am J Med Sci, 2010; 340:435–438.

109.

Zein

. Clinical significance of hepatitis C virus genotypes. Clin Microbiol Rev, 2000; 13:22335.

110.

Zeuzem

, Ghalib

, Reddy

, et al. Grazoprevir-elbasvir combination therapy for treatment-naive cirrhotic and noncirrhotic patients with chronic hepatitis C virus genotype 1, 4, or 6 infection: a randomized trial. Ann Intern Med, 2015; 163:1–13.

111.

Zimmer

, and Lammert

. Genetics and epigenetics in the fibrogenic evolution of chronic liver diseases. Best Pract Res Clin Gastroenterol, 2011; 25:269–280.

112.

Zoulim

, Chevallier

, Maynard

, et al. Clinical consequences of hepatitis C virus infection. Rev Med Virol, 2003; 13:57–68.