The high morbidity of HBV reactivation following allogeneic hematopoietic stem cell transplantation (allo-HSCT) is partially due to the intense immunologic potency of complex therapeutic regimens, the use of antithymocyte globulin and calcineurin inhibitors to prevent graft versus-host disease (GVHD), prolonged immune reconstitution, and hematological malignancies infected with hepatitis B virus (HBV). Immunosuppression results in the reactivation of HBV replication from covalently closed circular DNA (cccDNA) residing in hepatocytes. However, the role of viral mutations during HBV reactivation needs to be validated. All individuals scheduled to receive allo-HSCT or wish to donate stem cells should be screened for hepatitis B surface antigen (HBsAg), antibodies to hepatitis B core (anti-HBc), and HBV-DNA. HBsAg-positive recipients of allo-HSCT have a high risk of HBV reactivation; thus, they should receive prophylactic antiviral therapy. The high barrier to resistance nucleos(t)-ide analogs (NAs) seems to be superior to the low barrier agents. Resolved-HBV recipients have a lower risk of HBV reactivation than HBsAg-positive recipients. Although prophylactic antiviral therapy remains controversial, regular monitoring of alanine transaminase (ALT) and HBV-DNA combined with preemptive antiviral treatment may be an optimized strategy. However, optimal antiviral therapy duration and time intervals for monitoring remain to be established. Accepting stem cells from HBsAg-positive donors is associated with a risk of developing HBV-related hepatitis. The overall intervention strategy, including donors and recipients, may decrease the risk of HBV-related hepatitis following HSCT from HBsAg positive stem cells. In this review, we summarize the issues of HBV in allo-HSCT, including HBV reactivation mechanism, HBsAg-positive recipients, HBV-resolved infection recipients, and donor-related factors, and discuss their significance.

Viral hepatitis affects millions of people worldwide, and host immunity is the key determinant of patient outcome. Viral hepatitis can be life threatening in patients with haematological malignancy, including haemopoietic stem cell transplant recipients, because of the virus itself, or through a need to decrease the dose of chemotherapy. A past or currently infected haemopoietic stem cell donor could also transmit viral hepatitis. The burden of viral hepatitis in patients with haematological malignancies and the weak evidence on which previous guidelines are based has prompted the European Conference on Infection in Leukaemia (ECIL-5) to convene a group of experts in the fields of viral hepatitis and of haematological malignancy to specifically address previously unconsidered issues and grade the available quality of evidence according to the Infectious Diseases Society of America grading system. The group recommends that all patients should be screened for hepatotropic viruses before haematological treatment and that patients or haemopoietic stem cell donors with markers of past or current viral hepatitis should be assessed by an expert. Screening, vaccination, and treatment rules are reported in this Review.

Serologic evidence of resolved hepatitis B virus (HBV) infection has been associated with reactivation of hepatitis after allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the true impact of this finding is unknown. We conducted a retrospective matched-control analysis of the outcomes of 76 patients with positive HBV core antibody (HBcAb) and negative HBV surface antigen (HBsAg) at the time of allo-HSCT for hematologic or solid malignancies. Control patients (matched controls), with negative serology for HBV and other viral hepatitides, were matched by age, diagnosis, disease risk, intensity of conditioning regimen, and donor type. In addition, the HBcAb-positive patients and all seronegative patients (all controls, n = 1858) undergoing transplantation during the same period were compared to adjust for other confounding effects. Patient characteristics and baseline hepatic function studies were similar in the HBcAb-positive and matched control groups. The cumulative incidence of hepatitis B reactivation (defined as the emergence of HBsAg in serum) was 11.6% at 3 years. There were no significant differences in overall survival, relapse, nonrelapse mortality, and incidence of acute graft-versus-host disease between the HBcAb-positive and control groups. Our data suggest that seropositivity for HBcAb and seronegativity for HBsAg at the time of transplantation does not seem to adversely affect outcome after allo-HSCT.

Immunized against hepatitis B virus (HBV) recipients are at risk of developing HBV postallogeneic stem cell transplantation because of the potential loss of their HBV immunity. The aim of the study was to evaluate: (1) the HbsAb eradication incidence posttransplant and potential risk factors, (2) the impact of donor's immunity on HbsAb loss, (3) the incidence of hepatitis B in patients with HbsAb disappearance. We studied, retrospectively, in 26 vaccinated and 56 naturally immunized recipients, the posttransplant HbsAb titers for a median period of 36 (6-132) months. The probability of HbsAb loss and HBV-related hepatitis was determined in all recipients. The impact of donor's immunity origin in the HBsAb disappearance was evaluated in the subgroup of, actively or naturally, immunized recipients/donors pairs. The 5-year probability of HbsAb disappearance was 90% for all patients with 18% probability of developing hepatitis at 12 years, for those who lost HbsAb. Marrow graft, antithymocyte globulin administration, age<30 years and chronic graft-versus-host disease were significant risk factors for HbsAb loss. In the subgroup of immunized recipients/donors, the donor's active immunization significantly affected this loss. Allotransplanted patients are at high risk of losing protection against HBV. The adoptive transfer of active HBV immunity does not seem to offer sustained protection posttransplant.

This review describes the woodchuck and the woodchuck hepatitis virus (WHV) as an animal model for pathogenesis and therapy of chronic hepatitis B virus (HBV) infection and disease in humans. The establishment of woodchuck breeding colonies, and use of laboratory-reared woodchucks infected with defined WHV inocula, have enhanced our understanding of the virology and immunology of HBV infection and disease pathogenesis, including major sequelae like chronic hepatitis and hepatocellular carcinoma. The role of persistent WHV infection and of viral load on the natural history of infection and disease progression has been firmly established along the way. More recently, the model has shed new light on the role of host immune responses in these natural processes, and on how the immune system of the chronic carrier can be manipulated therapeutically to reduce or delay serious disease sequelae through induction of the recovery phenotype. The woodchuck is an outbred species and is not well defined immunologically due to a limitation of available host markers. However, the recent development of several key host response assays for woodchucks provides experimental opportunities for further mechanistic studies of outcome predictors in neonatal- and adult-acquired infections. Understanding the virological and immunological mechanisms responsible for resolution of self-limited infection, and for the onset and maintenance of chronic infection, will greatly facilitate the development of successful strategies for the therapeutic eradication of established chronic HBV infection. Likewise, the results of drug efficacy and toxicity studies in the chronic carrier woodchucks are predictive for responses of patients chronically infected with HBV. Therefore, chronic WHV carrier woodchucks provide a well-characterized mammalian model for preclinical evaluation of the safety and efficacy of drug candidates, experimental therapeutic vaccines, and immunomodulators for the treatment and prevention of HBV disease sequelae.

Reactivation of hepatitis B virus (HBV) infection following allogeneic bone marrow transplantation is a rare phenomenon.

Reverse seroconversion, defined as the clearance of antibody to hepatitis B surface antigen (HBsAb) and the appearance of hepatitis B surface antigen (HBsAg) in a patient with resolved HBV infection (i.e., a HBsAg-negative, HBsAb-positive, hepatitis B core antibody-positive patient) following receipt of a bone marrow transplant is described. A review of related cases in the literature was undertaken to identify clinical features associated with this phenomenon.

We present a case of reactivation of HBV infection in a 47-year-old man after receipt of an allogeneic bone marrow transplant for acute myelogenous leukemia. Before undergoing bone marrow transplantation, the presence of HBsAb and hepatitis B core antibody and the absence of HBsAg indicated clearance of natural HBV infection. The donor was HBsAg and HBsAb negative. Twenty-nine months after bone marrow transplantation, the patient developed transaminitis and evidence of active HBV infection (the patient had test results positive for HBsAg, negative for HBsAb, and positive for HBV DNA). A total of 28 other cases of reverse seroconversion have been described in the literature, 11 of which provided adequate information to be summarized in detail together with the present case. Reactivation of HBV infection following bone marrow transplantation appears to occur almost exclusively in patients who have received marrow from an HBsAb-negative donor and have experienced graft-versus-host disease, the onset of which is associated with tapering of immunosuppressive therapy.

Although HBV reverse seroconversion is an uncommon event, understanding the clinical features associated with the development of HBV reverse seroconversion may provide insight into how such a potentially fatal complication may be avoided.

Medical advances such as allogeneic transplantation can expose patients to periods of marked immunosuppression, during which viral infections are an important cause of morbidity and mortality. Control of infection will depend ultimately on the restoration of adequate antiviral immunity, and cellular immunotherapy is an attractive approach to improving immune protection. Developments in basic immunology have led to a greater understanding of the nature of protective immunity in immunocompetent donors, and this knowledge is now being used to direct immunotherapeutic protocols. Moreover, immunological techniques that have recently been developed as research tools, such as peptide-HLA tetramers and cytokine-secretion assays, have potential application for clinical use in this setting.

Between June 1994 and February 2003, a total of 111 human immunodeficiency virus (HIV)-infected patients with chronic hepatitis B virus (HBV) coinfection and 387 HIV-infected patients without HBV or hepatitis C virus coinfection were prospectively observed to assess the impact of HBV infection on outcomes of HIV-infected patients. After a median duration of observation of 25 months, coinfected patients were more likely to develop hepatitis (adjusted hazard ratio [AHR], 2.54; 95% confidence interval [CI], 1.69-3.82) and hepatic decompensation (adjusted odds ratio [AOR], 9.94; 95% CI, 1.89-52.35). Although similar proportions of the 2 patient groups had an increase in the CD4 count by > or =100x10(6) cells/L (AOR, 0.78; 95% CI, 0.45-1.36) and development of new opportunistic illnesses (AOR, 0.94; 95% CI, 0.53-1.66), HBV-infected patients had an increased risk for virologic failure (AOR, 1.76; 95% CI, 1.03-2.99) and death (AHR, 1.71; 95% CI, 1.19-2.47) after highly active antiretroviral therapy was initiated.

Suppression of the immune system and reconstitution of the donor's immune system may affect the course of a chronic viral infection in the recipients. The aim of this study is to evaluate changes in hepatitis B virus (HBV) serology after bone marrow transplantation (BMT). HBV serology and hepatic function tests were examined in 45 children before and after BMT. Before BMT, 40 patients were HBsAg negative and 5 positive. There were no HBsAg positive donors. HBsAg disappeared in two patients and anti-HBs became positive in one. Donors of these patients were anti-HBs positive. In a third patient, acute HBV infection developed and lasted without complication. This patient also seroconverted to anti-HBs. Anti-HBs disappeared in 7 of 21 anti-HBs positive patients. Among 18 patients who were HBsAg and anti-HBs negative, 11 seroconverted to anti-HBs positivity. Our findings support the notion that having an anti-HBs positive donor is important for adoptive immunity transfer and for preventing HBV replication.

Significant advances have been made in the treatment of both hepatitis B and C. Cure for the majority is becoming reality. Combination regimens are now established therapy in hepatitis C and the near future will see the adoption of a similar approach to hepatitis B. Interferon alpha therapy remains important, with the development of more efficacious pegylated forms. In this article we review current therapy and discuss future strategies of the therapy for chronic viral hepatitis.

Immune dysregulation and immunosuppression regimens impact on the ability of transplant recipients to respond to immunizations. The distinct challenges of immunizations to benefit stem cell transplant recipients and solid organ transplant recipients are discussed separately. Recommended vaccines for stem cell transplant recipients and solid organ transplant candidates are suggested. New approaches to consider to enhance immune responses of transplant recipients are discussed.

Interferon-alpha therapy has proved effective for up to 40% of patients with adult-acquired chronic hepatitis B virus (HBV) infection and for 20-25% of those with chronic hepatitis C virus (HCV) infection. Nucleoside analogues, such as lamivudine and famciclovir, are showing promise as antiviral agents for chronic HBV and the combination of interferon-alpha and ribavirin is proving to be successful therapy for 40-50% of patients with chronic HCV. In this article we review current therapy and discuss future strategies of the therapy of chronic viral hepatitis.