Hepatitis B Surface Antigen and Hepatitis C Virus Antibodies among Drug Users in Burkina Faso

Introduction: The epidemiology of both hepatitis B virus (HBV) and hepatitis C virus (HCV) infections among drug users (DUs) is little known in West Africa. The study aimed to assess the prevalence of hepatitis B and C viruses among drug users in Burkina Faso. Methodology: This was a cross-sectional biological and behavioral survey conducted between June and August 2022, among drug users in Ouagadougou and Bobo Dioulasso, the two main cities of Burkina Faso. A respondent-driven sampling (RDS) was used to recruit drug users. Hepatitis B surface antigen was determined using lateral flow rapid test kits and antibodies to hepatitis C virus in serum determined using an Enzyme-Linked Immunosorbent Assay. Data were entered and analyzed using Stata 17 software. Weighted binary logistic regression was used to identify the associated factors of hepatitis B and C infections and a p-value Results: A total of 323 drug users were recruited with 97.5% males. The mean age was 32.7 years old. The inhaled or smoked mode was the most used by drug users. The adjusted hepatitis B and hepatitis C prevalence among study participants were 11.1% and 2.3% respectively. The marital status (p = 0.001), and the nationality (p = 0.011) were significantly associated with hepatitis B infection. The type of drug used was not significantly associated with hepatitis B infection or hepatitis C infection. Conclusion: The prevalence of HBsAg and anti-HCV antibodies among DUs are comparable to those reported in the general population in Burkina Faso. This result suggests that the main routes of contamination by HBV and HCV among DUs are similar to those in the population, and could be explained by the low use of the injectable route by DUs in Burkina Faso.

Current and future antiviral drug therapies of hepatitis B chronic infection

Despite significant improvement in the management of chronic hepatitis B virus(HBV) it remains a public health problem, affecting more than 350 million people worldwide. The natural course of the infection is dynamic and involves a complex interplay between the virus and the host's immune system. Currently the approved therapeutic regimens include pegylated-interferon(IFN)-α and monotherapy with five nucleos(t)ide analogues(NAs). Both antiviral treatments are not capable to eliminate the virus and do not establish long-term control of infection after treatment withdrawal. IFN therapy is of finite duration and associates with low response rates, liver decompensating and numerous side effects. NAs are well-tolerated therapies but have a high risk of drug resistance development that limits their prolonged use. The imperative for the development of new approaches for the treatment of chronic HBV infection is a challenging issue that cannot be over-sided. Research efforts are focusing on the identification and evaluation of various viral replication inhibitors that target viral replication and a number of immunomodulators that aim to restore the HBV specific immune hyporesponsiveness without inducing liver damage. This review brings together our current knowledge on the available treatment and discusses potential therapeutic approaches in the battle against chronic HBV infection.

Chronic hepatitis B:New potential therapeutic drugs target

liverrelated morbidity and mortality worldwide.It impacts nearly 300 million people.The current treatment for chronic infection with the hepatitis B virus(HBV)is complex and lacks a durable treatment response,especially hepatitis B surface antigen(HBsAg)loss,necessitating indefinite treatment in most CHB patients due to the persistence of HBV covalently closed circular DNA(cccDNA).New drugs that target distinct steps of the HBV life cycle have been investigated,which comprise inhibiting the entry of HBV into hepatocytes,disrupting or silencing HBV cccDNA,modulating nucleocapsid assembly,interfering HBV transcription,and inhibiting HBsAg release.The achievement of a functional cure or sustained HBsAg loss in CHB patients represents the following approach towards HBV eradication.This review will explore the up-to-date advances in the development of new direct-acting anti-HBV drugs.Hopefully,with the combination of the current antiviral drugs and the newly developed direct-acting antiviral drugs targeting the different steps of the HBV life cycle,the ultimate eradication of CHB infection will soon be achieved.

Past,present,and future of long-term treatment for hepatitis B virus

The estimated world prevalence of hepatitis B virus(HBV)infection is 316 million.HBV infection was identified in 1963 and nowadays is a major cause of cirrhosis and hepatocellular carcinoma(HCC)despite universal vaccination programs,and effective antiviral therapy.Long-term administration of nucleos(t)ide analogues(NA)has been the treatment of choice for chronic hepatitis B during the last decades.The NA has shown a good safety profile and high efficacy in controlling viral replication,improving histology,and decreasing the HCC incidence,decompensation,and mortality.However,the low probability of HBV surface antigen seroclearance made necessary an indefinite treatment.The knowledge,in recent years,about the different phases of the viral cycle,and the new insights into the role of the immune system have yielded an increase in new therapeutic approaches.Consequently,several clinical trials evaluating combinations of new drugs with different mechanisms of action are ongoing with promising results.This integrative literature review aims to assess the knowledge and major advances from the past of hepatitis B,the present of NA treatment and withdrawal,and the future perspectives with combined molecules to achieve a functional cure.

Current therapeutic strategies for recurrent hepatitis B virus infection after liver transplantation

Hepatitis B virus (HBV)-related liver disease is the leading indication for liver transplantation (LT) in Asia,especially in China.With the introduction of hepatitis B immunoglobulin (HBIG) and oral antiviral drugs,the recurrent HBV infection rate after LT has been evidently reduced.However,complete eradication of recurrent HBV infection after LT is almost impossible.Recurrent graft infection may lead to rapid disease progression and is a frequent cause of death within the fi rst year after LT.At present,the availability of new oral medications,especially nucleoside or nucleotide analogues such as adefovir dipivoxil,entecavir and tenofovir disoproxil fumarate,further strengthens our ability to treat recurrent HBV infection after LT.Moreover,since combined treatment with HBIG and antiviral agents after liver re-transplantation may play an important role in improving the prognosis of recurrent HBV infection,irreversible graft dysfunction secondary to recurrent HBV infection in spite of oral medications should no longer be considered an absolute contraindication for liver re-transplantation.Published reviews focusing on the therapeutic strategies for recurrent HBV infection after LT are very limited.In this article,the current therapeutic strategies for recurrent HBV infection after LT and evolving new trends are reviewed to guide clinical doctors to choose an optimal treatment plan in different clinical settings.

Risk factors for hepatocellular carcinoma in patients with drug-resistant chronic hepatitis B

AIM:To investigate the risk factors and characteristics of hepatocellular carcinoma(HCC) in the patients with drug-resistant chronic hepatitis B(CHB).METHODS:A total of 432 patients with drug-resistant CHB were analyzed retrospectively from January 2004to December 2012. The patients were divided into two groups:the HCC group(n = 57) and the non-HCC group(n = 375). Two groups compared using logistic regression for various patients and viral characteristics in order to identify associated risk factors for HCC.Secondarily,patient and tumor characteristics of HCC patients with na ve CHB(N group,n = 117) were compared to the HCC group(R group,n = 57) to identify any difference in HCC characteristics between them.RESULTS:A significant difference was found for age,platelet count,alpha-fetoprotein(AFP),positivity of HBeAg,seroconversion rate of HBeAg,virologic response,the Child-Pugh score,presence of rtM204I,and the duration of antiviral treatment in non-HCC and HCC group. Cirrhosis,age(> 50 years),HBeAg(+),virologic non-responder status,and rtM204I mutants were independent risk factors for the development of HCC. The R group had lower serum C-reactive protein(CRP) and AFP levels,earlier stage tumors,and a shorter mean tumor surveillance period than the N group. However,the total follow-up duration was not significantly different between the two groups.CONCLUSION:13.2% of patients with drug-resistant CHB developed HCC. Age,cirrhosis,YIDD status,HBeAg status,and virologic response are associated with risk of HCC. Patients with drug-resistant CHB and these clinical factors may benefit from closer HCC surveillance.

Meta-analysis of combined therapy for adult hepatitis B virus-associated glomerulonephritis

AIM: To investigate the efficacy and safety of combined antiviral and immunosuppressant therapy in adult hepatitis B virus-associated glomerulonephritis (HBVGN) patients. METHODS: A computerized literature search was carried out in the PubMed database, Embase, the Cochrane Library, Chinese BioMedical Literature on disc, Chinese Medical Current Contents, Chinese National Knowledge Infrastructure, Wanfang and VIP (Chinese Technological Journal of Database) to collect articles between June 1980 and December 2010 on therapy with immunosuppressants, e.g., glucorticosteroids, mycophenolate mofetil and leflunomide, combined with antivirals, e.g., interferon, lamivudine, entecavir and adefovir dipivoxil, in adult HBV-GN patients. The primary outcomes were remission of proteinuria, clearanceof HBV e-antigen, and elevation of serum albumin. The secondary outcomes were blood levels of alanine aminotransferase, serum creatinine, and HBV-DNA titer. Meta-analysis was performed using Review Manager 5.1. Fixed or random effect models were employed to combine the results after a heterogeneity test. The effects of the combined therapy were analyzed for different doses of glucorticosteroid and different types of HBV-GN. RESULTS: Twelve clinical trials with 317 patients were included. A significantly higher incidence of HBV-GN was found in male patients (relative risk = 2.40, 95% CI: 1.98-2.93). Combined therapy reduced the proteinuria significantly with a mean difference of 4.19 (95% CI: 3.86-4.53) and increased the serum albumin concentration significantly with a mean difference of -11.95 (95% CI: -12.97-10.93) without significant alterations of liver function (mean difference: 4.62, 95% CI: -2.55-11.79) and renal function (mean difference: 10.29, 95% CI: 0.14-20.45). No signif icant activation of HBV-DNA replication occurred (mean difference: 0.12, 95% CI: -0.37-0.62). There was no significant difference between the high dose glucorticosteroid group and the low dose glucorticosteroid group in terms of proteinuria remission (P = 0.76) and between different pathological types of HBV-GN [membranous glomerulonephritis (MN) vs mesangial proliferative glomerulonephritis, P = 0.68; MN vs membranoproliferative glomerulonephritis, P = 0.27]. CONCLUSION: Combined antiviral and immunosuppressant therapy can improve the proteinuria in HBVGN patients without altering HBV replication or damaging liver and renal functions.

Molecular diagnosis and treatment of drug-resistant hepatitis B virus

Oral antiviral agents have been developed in the last two decades for the treatment of chronic hepatitis B(CHB).However,antiviral resistance remains an important challenge for long-term CHB therapy.All of the clinically available oral antiviral agents are nucleoside or nucleotide analogues that target the activity of viral reverse transcriptase(RT),and all are reported to have resistant mutations.Since the hepatitis B virus(HBV)RT,like other viral polymerases,lacks proofreading activity,the emergence of drug-resistance occurs readily under selective pressure from the administration of antiviral agents.The molecular diagnosis of drug-resistant HBV is based on sequence variations,and current diagnostic methods include sequencing,restriction fragment polymorphism analysis,and hybridization.Here,we will discuss the currently available molecular diagnosis tools,in vitro phenotypic assays for validation of drug-resistant HBV,and treatment options for drug-resistant HBV.

Current trends in management of hepatitis B virus reactivation in the biologic therapy era

Hepatitis B virus (HBV) reactivation represents an emerging cause of liver disease in patients undergoing treatment with biologic agents. In particular, the risk ofHBV reactivation is heightened by the use monoclonalantibodies, such as rituximab (anti-CD20) and alemtuzumab (anti-CD52) that cause profound and longlasting immunosuppression. Emerging data indicatethat HBV reactivation could also develop following theuse of other biologic agents, such as tumor necrosis factor (TNF)-α inhibitors. When HBV reactivation is di-agnosed, it is mandatory to suspend biologic treatmentand start antiviral agents immediately. However, preemptive antiviral therapy prior to monoclonal antibodyadministration is crucial in preventing HBV reactivationand its clinical consequences. Several lines of evidencehave shown that risk of HBV reactivation is greatlyreduced by the identifi cation of high-risk patients andthe use of prophylactic antiviral therapy. In this article, we discuss current trends in the management of HBV reactivation in immunosuppressed patients receiving biologic therapy, such as rituximab, alemtuzumab and TNF-α antagonists.

Hepatitis B virus infection reactivation in patients under immunosuppressive therapies:Pathogenesis,screening,prevention and treatment

With a 5.3%of the global population involved,hepatitis B virus(HBV)is a major public health challenge requiring an urgent response.After a possible acute phase,the natural history of HBV infection can progress in chronicity.Patients with overt or occult HBV infection can undergo HBV reactivation(HBVr)in course of immunosuppressive treatments that,apart from oncological and hematological diseases,are also used in rheumatologic,gastrointestinal,neurological and dermatological settings,as well as to treat severe acute respiratory syndrome coronavirus 2 infection.The risk of HBV reactivation is related to the immune status of the patient and the baseline HBV infection condition.The aim of the present paper is to investigate the risk of HBVr in those not oncological settings in order to suggest strategies for preventing and treating this occurrence.The main studies about HBVr for patients with occult hepatitis B infection and chronic HBV infection affected by non-oncologic diseases eligible for immunosuppressive treatment have been analyzed.The occurrence of this challenging event can be reduced screening the population eligible for immunosuppressant to assess the best strategies according to any virological status.Further prospective studies are needed to increase data on the risk of HBVr related to newer immunomodulant agents employed in non-oncological setting.

Long-term alpha interferon and lamivudine combination therapy in non-responder patients with anti-HBe-positive chronic hepatitis B:Results of an open,controlled trial

AIM: To investigate the safety and efficacy of long-term combination therapy with alpha interferon and lamivudine in non-responsive patients with anti-HBe-positive chronic hepatitis B.METHODS: 34 patients received combination treatment (1 month lamivudine, 12 month lamivudine+interferon, 6month lamivudine), 24 received lamivudine (12 months),24 received interferon (12 months). Interferon was administered at 6 MU tiw and lamivudine at 100 mg orally once daily. Patients were followed up for 6 months after treatment.RESULTS: At the end of treatment, HBV DNA negativity rates were 88 % with lamivudine+interferon, 99 % with lamivudine and 55 % with interferon, (P=0.004, combination therapy vs. interferon, and P=0.001 lamivudine vs.interferon), and serum transaminase normalization rates were 84 %, 91% and 53 % (P=0.01 combination therapy vs. interferon, and P=0.012 lamivudine vs. interferon). Six months later, HBV DNA negativity rates were 44 % with lamivudine+interferon, 33 % with lamivudine and 25 % with interferon, and serum transaminase normalization rates were 61%, 42 % and 45 %, respectively, without statistical significance. No YMDD variants were observed with lamivudine+interferon (vs. 12 % with lamivudine). The combination therapy appeared to be safe. CONCLUSION: Although viral clearance and transaminase normalization are slower with long-term lamivudine+interferon than that with lamivudine alone, the combination regimen seems to provide more lasting benefits and to protect against the appearance of YMDD variants. Studies with other regimens regarding sequence and duration are needed.

Treatment of hepatitis B virus-associated glomerulonephritis:A meta-analysis

AIM:To evaluate the efficacy of antiviral or corticosteroid treatment on hepatitis B virus-associated glomerulonephritis(HBV-GN) . METHODS:Six and five trials were used respectively to evaluate the efficacy of either antiviral or corticosteroid treatment on HBV-GN.Pediatric patients were pooled separately to assess their response to the above treatment modalities.The primary and secondary outcomes were remission of proteinuria and clearance of Hepatitis B e-antigen(HBeAg) ,respectively.A fixed or random effect model was established to collect the data. RESULTS:The remission rate of proteinuria(RR=1.69,95%CI:1.08-2.65) and the clearance rate of HBeAg(RR =6.44,95%CI:3.11-13.35) were significantly higher in antiviral treatment group than in control group.The proteinuria remission was significantly associated with HBeAg clearance(P=0.002) .However,the difference in proteinuria remission rate was not statistically significant between corticosteroid treatment group and controlgroup(RR=1.45,95%CI:0.68-3.11) .Antiviral therapy could significantly promote the HBeAg clearance in pediatric patients,but neither antiviral nor corticosteroid therapy could significantly decrease proteinuria in pediatric patients compared to controls. CONCLUSION:Antiviral but not corticosteroid treatment can decrease proteinuria and promote HBeAg clearance in HBV-GN patients.

Viral hepatitis prevalence in patients with active and latent tuberculosis

AIM: To assess the prevalence of hepatitis B virus(HBV) and hepatitis C virus(HCV) infection and association with drug induced liver injury(DILI) in patients undergoing anti-tuberculosis(TB) therapy.METHODS: Four hundred and twenty nine patients with newly diagnosed TB- either active disease or latent infection- who were due to commence antiTB therapy between September 2008 and May 2011 were included. These patients were prospectively tested for serological markers of HBV, HCV and human immunodeficiency virus(HIV) infections- hepatitis B core antigen(HBc Ag), hepatitis B surface antigen(HBs Ag), hepatitis B e antigen, Ig G and Ig M antibody to HBc Ag(anti-HBc), HCV Ig G antibody and HIV antibody using a combination of enzyme-linked immunosorbent assay, Western blot assay and polymerase chain reaction techniques. Patients were reviewed at least monthly during the TB treatment initiation phase. Liver function tests were measured prior to commencement of antiTB therapy and 2-4 wk later. Liver function tests were also performed at any time the patient had significant nausea, vomiting, rash, or felt non-specifically unwell. Fisher's exact test was used to measure significance in comparisons of proportions between groups. A P value of less than 0.05 was considered statistically significant.RESULTS: Of the 429 patients, 270(62.9%) had active TB disease and 159(37.1%) had latent TB infection. 61(14.2%) patients had isolated anti-HBc positivity, 11(2.6%) were also HBs Ag positive and 7(1.6%) were HCV-antibody positive. 16/270 patients with active TB disease compared to 2/159 patients with latent TB infection had markers of chronic viral hepatitis(HBs Ag or HCV antibody positive; P = 0.023). Similarly the proportion of HBs Ag positive patients were significantly greater in the active vs latent TB infection group(10/43 vs 1/29, P = 0.04). The prevalence of chronic HBV or HCV was significantly higher than the estimated United Kingdom prevalence of 0.3% for each. We found no association between DILI and presence of serological markers of HBV or HCV. Three(5.3%) patients with serological markers of HBV or HCV infection had DILI compared to 25(9.5%) patients without; P = 0.04.CONCLUSION: Viral hepatitis screening should be considered in TB patients. DILI risk was not increased in patients with HBV/HCV.

Treatment of chronic hepatitis B patients with tyrosinemethionine-aspartate-aspartate mutations

Lamivudine is an antiviral used for the treatment of chronic hepatitis B. Several studies have reported various mutations that are induced by lamivudine therapy. These mutations in the tyrosine-methionineaspartate-aspartate(YMDD) motif are necessary and sufficient to confer high-level lamivudine resistance. During treatment with lamivudine, mutations develop in the YMDD motif of the hepatitis B virus(HBV) polymerase gene and lamivudine cannot prevent the replication of the mutant form. The virulence strain of developed mutation in the polymerase gene is lower than the original virus and they are susceptible to treatment with some other nucleoside analogs except lamivudine. Entecavir and tenofovir are potent HBV inhibitors and they can be confidently used as first line monotherapies. We read the article written by Tan et al that lamivudine therapy improved the clinical course in HBV patients with natural YMDD mutations. We think that lamivudine use for this patient group is not appropriate. These patients should use YMDD mutant form-effective drugs such as adefovir, tenofovir.

Differing profiles of people diagnosed with acute and chronic hepatitis B virus infection in British Columbia,Canada

AIM To describe the characteristics of people diagnosed with acute and chronic hepatitis B virus(HBV) infection in British Columbia(BC).METHODS We used data from the BC Hepatitis Testers Cohort(BCHTC),which includes all individuals tested for hepatitis C virus(HCV) or human immunodeficiency virus(HIV) or those diagnosed with HBV or active tuberculosis in BC since 1990.These data were integrated with prescription drug,medical visit,hospitalization and mortality data.HBV cases were classified as acute or chronic according to provincial guidelines.We compared characteristics of individuals by HBV infection group(acute,chronic and negative).Factors associated with acute or chronic HBV infection were assessed with multinomial logistic regression models in comparison to the HBV negative group.RESULTS46498 of the 1058056 eligible BC-HTC participants were diagnosed with HBV infection.4.3% of HBV positive individuals were diagnosed with acute HBV infections while 95.7% had chronic infections.Problematic alcohol use,injection drug use,and HIV or HCV co-infection were more common among individuals diagnosed with acute HBV compared to those with chronic infections and HBV negative individuals.In multivariable multinomial logistic regression models,we observed significant associations between acute or chronic HBV diagnosis and being male,age at HBV diagnosis or birth cohort,South and East Asian ethnicity,HCV or HIV infection,and injection drug use.The odds of acute HBV decreased with increasing age among people who inject drugs,while the opposite was true for chronic HBV.Persons with acute HBV were predominantly White(78%) while those with chronic HBV were mostly East Asian(60%).Relative to Whites,East Asians had 12 times greater odds of being diagnosed with chronic HBV infection.These odds increased with increasing socioeconomic deprivation.CONCLUSION Differences in the profiles of people diagnosed with acute and chronic HBV infection necessitate differentiated screening,prevention,care and treatment programs.

Clinical relevance of hepatitis B virus variants

The hepatitis B virus(HBV) is a global public health problem with more than 240 million people chronically infected worldwide, who are at risk for end-stage liver disease and hepatocellular carcinoma. There are an estimated 600000 deaths annually from complications of HBV-related liver disease. Antiviral therapy with nucleos/tide analogs(NA) targeting the HBV polymerase(P) can inhibit disease progression by long-term suppression of HBV replication. However, treatment may fail with first generation NA therapy due to the emergence of drugresistant mutants, as well as incomplete medication adherence. The HBV replicates via an error-prone reverse transcriptase leading to quasispecies. Due to overlapping open reading frames mutations within the HBV P can cause concomitant changes in the HBV surface gene(S) and vice versa. HBV quasispecies diversity is associated with response to antiviral therapy, disease severity and long-term clinical outcomes. Specific mutants have been associated with antiviral drug resistance, immune escape, liver fibrosis development and tumorgenesis. An understanding of HBV variants and their clinical relevance may be important for monitoring chronic hepatitis B disease progression and treatment response. In this review, we will discuss HBV molecular virology, mechanism of variant development, and their potential clinical impact.

Naturally derived anti-hepatitis B virus agents and their mechanism of action

Despite that some approved drugs and genetically engineered vaccines against hepatitis B virus(HBV)are available for HBV patients,HBV infection is still a severe public health problem in the world.All the approved therapeutic drugs(including interferonalpha and nucleoside analogues)have their limitations.No drugs or therapeutic methods can cure hepatitis B so far.Therefore,it is urgently needed to discover and develop new anti-HBV drugs,especially nonnucleoside agents.Naturally originated compounds with enormous molecular complexity and diversity offer a great opportunity to find novel anti-HBV lead compounds with specific antiviral mechanisms.In this review,the natural products against HBV are discussed according to their chemical classes such as terpenes,lignans,phenolic acids,polyphenols,lactones,alkaloids and flavonoids.Furthermore,novel mode of action or new targets of some representative anti-HBV natural products are also discussed.The aim of this review is to report new discoveries and updates pertaining to anti-HBV natural products in the last 20years,especially novel skeletons and mode of action.Although many natural products with various skeletons have been reported to exhibit potent anti-HBV effects to date,scarcely any of them are found in the list of conventional anti-HBV drugs worldwide.Additionly,in anti-HBV mechanism of action,only a few references reported new targets or novel mode of action of antiHBV natural products.

Application of hepatitis B virus replication mouse model

AIM:To evaluate the value of the hepatitis B virus(HBV) replication mouse model with regard to several aspects of the study of HBV biology.METHODS:To evaluate the HBV replication mouse model in detecting the efficacy of anti-HBV agents,the interferon inducer polyinosinic-polytidylin acid(polyIC) and nucleotide analogues adefovir and entecavir were administered to mice injected with wild type pHBV4.1,and the inhibiting effect of these agents on HBV DNA replication was evaluated.To identify the model's value in a replication ability study of HBV drug-resistant mutants and a HBx-minus mutant,telbivudine resistance mutants(rtM204I,ayw subtype),adefovir resistance mutants(rtA181V + rtN236T,ayw subtype) and HBxminus mutants were injected respectively,and their corresponding HBV DNA replication intermediates in mouse liver were assessed.RESULTS:Compared with the wild type HBV replication mouse model without antiviral agent treatment,the HBV DNA replication intermediates of the polyICtreated group were decreased 1-fold;while in the entecavir-and adefovir-treated groups,the levels of HBV DNA replication intermediates were inhibited 13.6-fold and 1.4-fold,respectively.For the mouse models injected with telbivudine resistance mutant,adefovir resistance mutant and HBx-minus mutant,HBV DNA replication intermediates could still be detected,but the levels of HBV DNA replication intermediates of these mutants decreased 4.5-fold,5.6-fold and 2.9-fold respectively,compared with the mouse model with wild type HBV plasmid.CONCLUSION:The HBV replication mouse model we established was a useful and convenient tool to detect the efficacy of antiviral agents and to study the replication ability of HBV mutants in vivo.

Search for a cure for chronic hepatitis B infection: How close are we?

Chronic hepatitis B(CHB) remains a significant unmet medical need, with 240 million chronically infected persons worldwide. It can be controlled effectively with either nucleoside/nucleotide-based or interferonbased therapies. However, most patients receiving these therapies will relapse after treatment withdrawal. During recent years, the advances in molecular biology and immunology have enabled a better understanding of the viral-host interaction and inspired new treatment approaches to achieve either elimination of the virus from the liver or durable immune control of the infection. This review aims to provide a brief overview on the potential new therapies that may overcome the challenge of persistent CHB infection in the near future.

Clinical implications of hepatitis B virus mutations:Recent advances

Hepatitis B virus(HBV)infection is a major cause of acute and chronic hepatitis,and of its long-term complications.It is the most variable among DNA viruses,mostly because of its unique life cycle which includes the activity of error-prone enzyme,reverse transcriptase,and the very high virion production per day.In last two decades,numerous research studies have shown that the speed of disease progression,reliability of diagnostic methods and the success of antiviral therapy and immunization are all influenced by genetic variability of this virus.It was shown that mutations in specific regions of HBV genome could be responsible for unwanted clinical outcomes or evasion of detection by diagnostic tools,thus making the monitoring for these mutations a necessity in proper evaluation of patients.The success of the vaccination programs has now been challenged by the discovery of mutant viruses showing amino acid substitutions in hepatitis B surface antigen(HBsAg),which may lead to evasion of vaccine-induced immunity.However,the emergence of these mutations has not yet raised concern since it was shown that they develop slowly.Investigations of HBV genetic variability and clinical implications of specific mutations have resulted in significant advances over the past decade,particularly in regard to management of resistance to antiviral drugs.In the era of drugs with high genetic barrier for resistance,on-going monitoring for possible resistance is still essential since prolonged therapy is often necessary.Understanding the frequencies and clinical implications of viral mutations may contribute to improvement of diagnostic procedures,more proper planning of immunization programs and creating the most efficient therapeutic protocols.