The role of HBIg as hepatitis B reinfection prophylaxis following liver transplantation

Exchanges in the 'a' determinant of the hepatitis B virus surface antigen revisited

The hepatitis B virus surface antigen's (HBsAg) 'a' determinant comprises a sequence of amino acid residues located in the major hydrophilic region of the S protein, whose exchanges are closely associated with compromising the antigenicity and immunogenicity of that antigen. The HBsAg is generally present in the bloodstream of individuals with acute or chronic hepatitis B virus (HBV) infection. It is classically known as the HBV infection marker, and is therefore the first marker to be investigated in the laboratory in the clinical hypothesis of infection by this agent. One of the factors that compromises the HBsAg detection in the bloodstream by the assays adopted in serological screening in both clinical contexts is the loss of S protein antigenicity. This can occur due to mutations that emerge in the HBV genome regions that encode the S protein, especially for its immunodominant region - the 'a' determinant. These mutations can induce exchanges of amino acid residues in the S protein's primary structure, altering its tertiary structure and the antigenic conformation, which may not be recognized by anti-HBs antibodies, compromising the infection diagnosis. In addition, these exchanges can render ineffective the anti-HBs antibodies action acquired by vaccination, compromise the effectiveness of the chronically HBV infected patient's treatment, and also the HBsAg immunogenicity, by promoting its retention within the cell. In this review, the residues exchange that alter the S protein's structure is revisited, as well as the mechanisms that lead to the HBsAg antigenicity loss, and the clinical, laboratory and epidemiological consequences of this phenomenon.

Polyclonal hyper immunoglobulin: A proven treatment and prophylaxis platform for passive immunization to address existing and emerging diseases

Passive immunization with polyclonal hyper immunoglobulin (HIG) therapy represents a proven strategy by transferring immunoglobulins to patients to confer immediate protection against a range of pathogens including infectious agents and toxins. Distinct from active immunization, the protection is passive and the immunoglobulins will clear from the system; therefore, administration of an effective dose must be maintained for prophylaxis or treatment until a natural adaptive immune response is mounted or the pathogen/agent is cleared. The current review provides an overview of this technology, key considerations to address different pathogens, and suggested improvements. The review will reflect on key learnings from development of HIGs in the response to public health threats due to Zika, influenza, and severe acute respiratory syndrome coronavirus 2.

An Overview of the Current Hepatitis B Treatment Strategies after Liver Transplantation

Currently, liver transplantation (LT) is considered as the only option for the treatment of patients with various causes of liver failure, including patients with chronic hepatitis B virus (HBV) infections. Overall, patients with HBV who undergo LT are at increased risk of hepatitis B infection recurrence. Although the current knowledge regarding the pathophysiology of this infection has been dramatically increased over the past few decades, it is still considered a complex disease process with varying degrees of clinical characteristics and changing patterns over time. There are various treatment strategies for preventing HBV recurrence in the LT setting. Generally, these regimens include oral nucleoside/ nucleotide analogues (NAs), hepatitis B immune globulin (HBIG), and vaccines or the combination of these drugs. The treatment strategy of choice should be based on cost-effectiveness, along with other patients underlying conditions. In this case, studies indicate that potent NAs are more cost-effective than HBIG in most case scenarios. In this article, we aimed to review the general medications used in the prophylaxis of the recurrence of HBV infection after LT.

The efficiency of low-dose hepatitis B immunoglobulin plus nucleos(t)ide analogs in preventing posttransplant hepatitis B virus recurrence

Background/aim

In this study, the efficiency of using low-dose hepatitis B immunoglobulin (HBIG) plus antiviral treatment according to individual needs has been evaluated in posttransplant hepatitis B virus (HBV) patients.

Materials and methods

We retrospectively evaluated 179 patients who were admitted between 2009 and 2014. Five thousand IU intravenous HBIG was given in the anhepatic phase, and 400 IU/day intramuscular (IM) HBIG was given in the posttransplant period. After HBsAg seroconversion, 400 IU IM HBIG was continued as prophylaxis every two weeks.

Results

The average follow-up period was 26 (2–65) months. Seventy patients had hepatocellular carcinoma (HCC). The HBV recurrence was 4.5% in the first year, and 5.8% in the third year. The HBsAg became negative in 11 (2–63) days, and anti-HBs became positive in 9 (1–31) days. HBsAg positivity occurred in 6 patients during the follow-up period. Five of these patients were those who underwent transplantation due to HCC. In 5 of the HCC patients, in whom HBsAg became positive, tumor recurrence was observed after 0.3–9.9 months. HBsAg positivity was more frequently detected in patients with HCC (P = 0.009).

Conclusion

The HBV recurrence should be evaluated as a predictor of the HCC recurrence in patients who were transplanted due to HCC.

Adefovir- or Lamivudine-Induced Renal Tubular Dysfunction after Liver Transplantation

To reduce hepatitis B virus reinfection after liver transplantation (LT), patients often receive antihepatitis B immunoglobulin (HBIG) alone or combined with antiviral nucleoside/nucleotide analogs (NUCs); however, proximal renal tubular dysfunction (RTD) that was induced by NUCs in liver recipients was rarely reported. Here, we analyzed RTD and renal impairment (RI) following adefovir (ADV) and lamivudine (LAM) treatment in liver recipients. We retrospectively reviewed medical records of patients treated with HBIG alone (group 1, n = 42) or combined with ADV or LAM (group 2, n = 21) after LT. We compared RTD and RI incidence during the 12 months after LT. An RTD diagnosis required manifestation of at least 3 of the following features: hypophosphatemia, RI, hypouricemia, proteinuria, or glucosuria. No significant differences were observed regarding sex, age, donor type, model of end-stage liver score, and estimated glomerular filtration rate at pre-LT between the 2 groups. Hepatitis B virus recurrence within 12 months was 4.8% in both groups (P = 1.000); however, the RTD incidence was 0% in group 1 and 19.0% in group 2 (P = 0.010). RI occurrence did not differ between the groups. The only risk factor for RI was HBIG administration combined with both LAM and ADV (odds ratio 11.27, 95% confidence interval 1.13-112.07, P = 0.039, vs HBIG alone). RTD occurred more frequently in patients treated with HBIG combined with LAM or ADV compared with HBIG alone. Thus, LAM or ADV therapy can induce RTD after LT, and when administered, liver recipients should be monitored.

A new scheme with infusion of hepatitis B immunoglobulin combined with entecavir for prophylaxis of hepatitis B virus recurrence among liver transplant recipients

OBJECTIVE

Liver transplantation significantly increases recurrence of hepatitis B virus (HBV) among high-risk patients. Hepatitis B immunoglobulin (HBIG) and antiviral nucleotide analogues are effective prophylaxis reagents in preventing HBV recurrence. However, HBV recurrence still occurs with these treatments.

METHODS

To explore a more cost-effective prophylaxis protocol in patients after liver transplantation, we treated patients with an initial high dose of 10 000 IU HBIG during the anhepatic phase and a second high dose of HBIG at an optimal time point during surgery. The patients were treated with the traditional European protocol as a control, in which one dose of 10 000 IU HBIG was infused during the anhepatic phase and multiple doses of 10 000 IU HBIG were administered daily for 1 week after liver transplantation.

RESULTS

There were two mortalities among 50 patients treated with the new protocol and nine mortalities among 52 patients treated with the European protocol within 3 years after liver transplantation. The new prophylaxis method markedly improved the 3-year survival without HBV recurrence in 50 treated patients. However, there were five recurrences in 52 patients treated with the European protocol. High-risk factors such as HBV DNA+, positive hepatitis B e antigen, and hepatocellular carcinoma were all detected among five patients with HBV recurrence. The suppressed HBV recurrence was associated with significantly lower serum alanine aminotransferase and aspartate aminotransferase in the new protocol-treated patients tested at 1 month and 1 week after liver surgery compared with those treated with the European protocol.

CONCLUSION

Infusion of two high doses of HBIG during surgery in combination with entecavir significantly prevented HBV recurrence and improved the 3-year survival after liver transplantation.

Tenofovir-emtricitabine therapy for the prevention of hepatitis B recurrence in four patients after liver transplantation

In patients infected with chronic hepatitis B virus (HBV) that goes untreated, therapeutic options are limited once the disease decompensates, and orthotopic liver transplantation is often the only treatment available to save the patient's life. After liver transplantation, combined therapy with hepatitis B immune globulin (HBIG) and a nucleos(t)ide analog is the standard of practice for the prevention of HBV recurrence. Historically, nucleos(t)ide analogs such as lamivudine and adefovir have been used with low-dose HBIG for the prevention of HBV recurrence after liver transplantation. However, these analogs are ineffective when used alone due the emergence of resistance mutations. Newer nucleos(t)ide analogs such as tenofovir disoproxil fumarate have demonstrated higher resistance thresholds and effective viral suppression when paired with low-dose HBIG. In this case series, we evaluated the safety and efficacy of switching four patients from low-dose HBIG plus nucleos(t)ide analog therapy for the prevention of HBV recurrence to a combination tenofovir-emtricitabine regimen. At the end of follow-up, all patients remained hepatitis B surface antigen negative and had HBV DNA levels of less than 10 IU/ml. Additionally, no tenofovir-associated nephrotoxicity was observed among the four patients. Tenofovir-emtricitabine monotherapy in lieu of HBIG plus nucleos(t)ide analog therapy demonstrated prevention of HBV recurrence without tenofovir-associated nephrotoxicity after 9 months of follow-up in all four patients and up to 15 months in one patient.