Low-level hepatitis C viremia and humoral immune response to NS4 in chronic hepatitis B virus-hepatitis C virus coinfection

Impact of previous hepatitis B infection on the clinical outcomes from chronic hepatitis C? A population-level analysis

Chronic coinfection with hepatitis C virus (HCV) and hepatitis B virus (HBV) is associated with adverse liver outcomes. The clinical impact of previous HBV infection on liver disease in HCV infection is unknown. We aimed at determining any association of previous HBV infection with liver outcomes using antibodies to the hepatitis B core antigen (HBcAb) positivity as a marker of exposure. The Scottish Hepatitis C Clinical Database containing data for all patients attending HCV clinics in participating health boards was linked to the HBV diagnostic registry and mortality data from Information Services Division, Scotland. Survival analyses with competing risks were constructed for time from the first appointment to decompensated cirrhosis, hepatocellular carcinoma (HCC) and liver-related mortality. Records of 8513 chronic HCV patients were included in the analyses (87 HBcAb positive and HBV surface antigen [HBsAg] positive, 1577 HBcAb positive and HBsAg negative, and 6849 HBcAb negative). Multivariate cause-specific proportional hazards models showed previous HBV infection (HBcAb positive and HBsAg negative) significantly increased the risks of decompensated cirrhosis (hazard ratio [HR]: 1.29, 95% CI: 1.01-1.65) and HCC (HR: 1.64, 95% CI: 1.09-2.49), but not liver-related death (HR: 1.02, 95% CI: 0.80-1.30). This is the largest study to date showing an association between previous HBV infection and certain adverse liver outcomes in HCV infection. Our analyses add significantly to evidence which suggests that HBV infection adversely affects liver health despite apparent clearance. This has important implications for HBV vaccination policy and indications for prioritization of HCV therapy.

Hepatitis B reactivation during or after direct acting antiviral therapy - implication for susceptible individuals

INTRODUCTION

The FDA issued a warning following 24 cases of HBV reactivation during DAA therapy for HCV, including individuals with inactive, occult and past HBV infection. Clinical presentations ranged from asymptomatic fluctuations in HBV DNA to fulminant hepatic failure, liver transplantation and death. The mechanism is unknown. Areas covered: HCV/HBV coinfection is common, particularly in regions endemic for HBV. HCV and HBV utilize host factors to support replication; both viruses evade/impair host immunity. Clinical presentations of HBV reactivation during DAAs are summarized. Other causes of HBV reactivation are revisited and recent data regarding HBV reactivation are presented. Expert opinion: HBV reactivation during DAAs for HCV occurs, with life-threatening consequences in some individuals. The risk of HBV reactivation is observed in all HBV stages. The rapid removal of HCV likely alters and liberates host-viral ± viral-viral interactions that lead to increased HBV replication. As immune reconstitution occurs with HCV removal, host recognition of HBV DNA likely ensues followed by vigorous host immune responses leading to liver injury (HBV flare). These cases highlight the importance of HBV testing prior to initiating DAA therapy, the need for close monitoring of HBV during therapy and timely administration of anti-HBV therapy to prevent serious sequelae.

HBV/HCV dual infection impacts viral load, antibody response, and cytokine expression differently from HBV or HCV single infection

Hepatitis B virus/hepatitis C virus (HBV/HCV) dual infection is common among high-risk individuals. To characterize the virological and immunological features of patients with HBV/HCV dual infection, we enrolled 1,049 individuals who have been identified as injection drug users. Patients were divided into single and dual infection groups according to the serological markers. We found the average HCV RNA level was significantly lower; however, HBV viral load was significantly higher in HBV/HCV dual-infected patients (n = 42) comparing HCV single infection (n = 340) or HBV single infection (n = 136). The level of anti-HBs in patients who experienced spontaneous HBV clearance was higher than that in HCV single-infected patients with HBV spontaneous clearance. The level of anti-HCV E2 in HBV/HCV dual infection was lower than that detected in HCV single infection. Serum levels of IL-6, IL-8, and TNF-α were significantly lower in HBV/HCV dual-infected patients than in patients infected with HBV or HCV alone. Taken together, two viral replications are imbalanced in dual infected patients. The anti-HBs and anti-HCV E2 antibody production were impaired and proinflammatory IL-6, IL-8, and TNF-α also downregulated due to dual infection. These findings will help further understanding the pathogenesis of HBV/HCV dual infection.

Synthetic antigens representing the antigenic variation of human hepatitis C virus

Immune responses against hepatitis C virus (HCV) have been studied by numerous groups. However, details concerning the production of antibodies to antigenically variable epitopes remain to be elucidated. Since the sequences of the variable regions of several HCV proteins are different among the virus strains infecting patients, we decided to design peptide combinations that represent the theoretical maximum antigenic variation of each epitope to be used as capture antigens. We prepared six peptide mixtures (hypervariable epitope constructs; HECs) representing six different epitopes from structural and non-structural proteins of HCV from genotypes 1-6. Plasma from 300 HCV patients was tested to determine if their antibodies recognize the synthetic constructs. All the patients were chronically infected with diverse HCV genotypes and did not receive antiviral treatment. Antibodies to one or more of the HECs were detected in all of the HCV-infected individuals. Immunogenicity of the HCV HECs was also evaluated in outbred and inbred mice. Strong HEC-specific antibodies were produced, and cellular responses were also induced that were Th-1 rather than Th-2. Our results show that HCV HECs are both antigens that can be used to detect the broad cross-reactivity of antibodies from HCV-infected patients, and strong immunogens that can induce antigen-specific humoral and cellular immune responses in mice.

Liver transplantation for hepatitis B and C virus-related cirrhosis: mid-term results

Hepatitis C virus (HCV) recurrence after orthotopic liver transplantation (OLT) is almost universal; cirrhosis develops in up to 30% of cases. Currently there is interest in the midterm outcomes of HCV patients with concomitant hepatitis B virus (HBV) infection among OLT recipients. We therefore retrospectively analyzed our database of patients who underwent OLT for HCV-HBV-related cirrhosis. Between April 1992 and December 2008, 350 patients underwent OLT, including 20 (5.7%) transplanted for HBV-HCV cirrhosis. We assessed patient and graft survivals at 1 and 5 years, as well as the progression of fibrosis. Protocol liver biopsies were available yearly after OLT. The survival curves were analyzed by the Kaplan-Meier approach and chronic hepatitis evaluated according to the Ishak scoring system. At a median follow-up of 68.4 +/- 53 months, the 1- and 5-year patient and graft survival rates were 80% and 70%, respectively. The 5-year fibrosis progression rate was 0.17 +/- 0.08 units of fibrosis. The only patient who developed histologic cirrhosis within 10 years of follow-up showed a lamivudine-resistant HBV recurrence. Patients transplanted for HBV-HCV coinfection showed a lower fibrosis progression rate compared with HCV monoinfected subjects.

Management of patients co-infected with HBV and HCV

HBV and HCV are both hepatotrophic pathogens that share common routes of transmission, namely through exposure to infected blood and body fluids. Available natural history studies suggest dual infection with HBV and HCV increases the risk of progressive liver disease, and the risk of cirrhosis and liver cancer. Owing to the dynamic nature of these chronic infections, with fluctuations in viral level and disease activity, close monitoring is needed to determine the appropriate time to intervene with treatment. The clinical profile most commonly encountered is for active HCV infection (HCV RNA-positive) with or without active HBV infection (HBsAg-positive with variable HBV DNA levels). For these patients, treatment with pegylated interferon and ribavirin is the treatment of choice. For those with HBV-predominant disease (and HCV RNA-undetectable), the treatment is identical to that with HBV infection alone. For patients unresponsive to these initial treatments, there are no specific guidelines, and additional studies to define the treatment algorithms for nonresponders or relapsers are needed.

Longer survival of liver transplant recipients with hepatitis virus coinfections

Hepatitis virus coinfections [HBV plus HCV coinfection (HBV/HCV) or HBV plus HDV coinfection (HBV/HDV)] may progress more rapidly to cirrhosis than hepatitis B or C monoinfections in immunocompetent patients. Only limited information is available on the outcome of coinfected patients after liver transplantation. We studied survival rates of 204 patients with viral hepatitis transplanted at our center between 1972 and 1997. HBV/HDV and HBV/HCV coinfections were present in 23 and nine individuals, respectively, while 97 patients had monoinfection by HCV and 75 had HBV monoinfection. Survival of coinfected patients was significantly longer than that of monoinfected patients (14.4 +/- 0.9 vs. 8.5 +/- 0.6 yr; p = 0.0003). The same was true for graft survival (p = 0.0002). In Cox's regression, viral coinfection (p = 0.0001), absence of hepatocellular carcinoma (HCC) (p = 0.00001) and no retransplantation (p = 0.02) were independently associated with patient survival. After exclusion of patients with HCC (n = 62), survival of coinfected patients was still significantly longer than that of monoinfected individuals (p = 0.002). The improved outcome was similar for both HBV/HDV and HBV/HCV coinfections. In contrast to immunocompetent patients, individuals with multiple hepatitis virus infections had an improved outcome after liver transplantation. Thus, viral coinfections may be associated with ameliorated courses of diseases under certain conditions.

Viral interaction and clinical implications of coinfection of hepatitis C virus with other hepatitis viruses

Coinfection with other hepatitis viruses modifies the viral profile in serum and leads to more liver damage and more rapid progression during the course of hepatitis C virus infection. The viral interference is not only carried out by virus-virus or by virus-cell interactions but also by an enhanced immune response. A superinfecting viral infection does not crossactivate protective immune responses to the pre-existing virus albeit the latter can become undetectable. The induced cytokine stimulation might enhance the hepatic inflammation. Moreover, hepatitis B virus coinfection increases the risk of development of hepatocellular carcinoma in hepatitis C virus patients through common necro-inflammatory pathways or by direct oncogenic activity of hepatitis B virus. Viral interaction also complicates the management of the coinfection because hepatitis C virus impairs the humoral response to hepatitis A virus and hepatitis B virus vaccines, and because pharmacological suppression of hepatitis C virus endangers dually infected patients with reactivation of coinfected hepatitis B virus. Optimized strategies and follow-up are thus necessary in the treatment of infection with multiple viruses. It seems thus necessary to look for markers of hepatitis B virus and/or hepatitis D virus infection in chronic hepatitis patients positive for hepatitis C virus antibodies but negative for hepatitis C virus RNA, and equally well to search for hepatitis C virus RNA in HBsAg-negative/anti-HBc-positive patients with a low level of serum hepatitis B virus DNA.

Optimizing management strategies in special patient populations

Chronic hepatitis B infection presents a number of challenges to clinicians. There are additional considerations when defining management strategies for individuals with advanced liver disease, or coinfection, or those at high risk of developing hepatocellular carcinoma (HCC). Treatment of decompensated cirrhosis is particularly important. Evidence suggests that suppression of viral replication through nucleos(t)ide analog therapy leads to longer time to transplantation, improved liver function, and improved survival times. The use of interferon in patients with decompensated hepatitis B is associated with serious complications and is currently contraindicated for these patients by the AASLD Practice Guidelines. Hepatitis B coinfection is often associated with more extensive disease. In patients with HBV/HCV coinfection, one disease is usually dominant and consequently should be the focus of therapy. HIV/HBV coinfection increases the risk of progressive liver disease. Therapeutic agents active against both viruses should be utilized at the correct dose to limit the development of resistance. Agents specific for HBV, e.g., entecavir, enable hepatitis to be treated while avoiding the risk of HIV resistance developing. Dual infection with HBV and HDV is particularly challenging. Nucleos(t)ide analogs are ineffective in treating HDV infection, and there is limited data concerning the efficacy of interferon in this setting. The association between chronic hepatitis B infection and hepatocellular carcinoma (HCC) is well established. In patients at high risk of HCC, screening regimes may be effective. Furthermore, there is an increasing body of evidence indicating that effective suppression of viral replication may be associated with a reduced risk of HCC.