Antiviral therapy for hepatitis B virus infections: new targets and technical challenges.

There are presently only two licensed therapies for treating liver disease caused by infection with the hepatitis B virus (HBV). These are interferon-alpha and lamivudine. Neither agent was specifically developed as an antiviral compound for treating patients infected with HBV. Both therapies are limited in the clinic by a low response rate and in the case of lamivudine, selection of drug-resistant mutants, whilst troublesome side effects limit the use of interferon-alpha. Several promising nucleoside/nucleotide analogues are undergoing clinical trials, including adefovir dipivoxil and entecavir, both of which appear to be active against lamivudine- resistant HBV. In addition to these nucleoside/nucleotide analogues, it will be important to develop new agents with different modes of action, which can be added to the antiviral cocktails that will be required to adequately suppress and hopefully eliminate HBV replication.     

The woodchuck: A model for therapeutic vaccination against hepadnaviral infection

Interferon-α and nucleoside analogues are available for the treatment of chronic hepatitis B virus (HBV) infection but do not lead to a satisfactory result. New findings about the immunological control of HBV during acute infection suggest the pivotal role of T-cell mediated immune responses. Several preclinical and clinical trials were undertaken to explore the possibility of stimulating specific immune responses in chronically infected animals and patients by vaccination. However, vaccination with commercially available HBV vaccines in patients and immunization in woodchucks with core or surface proteins of woodchuck hepatitis virus (WHV) did not result in effective control of HBV and WHV infection, suggesting that new formulations of therapeutic vaccines are needed. Some new approaches combining antiviral treatments with nucleoside analogues, DNA vaccines and protein vaccines were tested in the woodchuck model. It could be shown that therapeutic vaccinations are able to stimulate specific B- and T-cell responses and to achieve transient suppression of viral replication. These results suggest the great potential of therapeutic vaccination in combination with antivirals to reach an effective and sustained control of HBV infection.     

Immune balance in Hepatitis B Infection: Present and Future Therapies

Chronic hepatitis B virus (HBV) infection affects millions of people worldwide and about half a million people die every year. India represents the second largest pool of chronic HBV infections with an estimated 40 million chronically infected patients. Persistence or clearance of HBV infection mainly depends upon host immune responses. Chronically infected individuals remain in immune tolerant phase unless HBV flares and leads to the development of chronic active hepatitis or acute‐on‐chronic liver failure. Strategies based on inhibition of viral replication (nucleoside analogues) or immune modulation (interferons) as monotherapy, or in combination in sequential therapies, are currently being used globally for reducing HBV viral load and mediating HBsAg clearance. However, the immune status and current therapies for promoting sustained virological responses in HBV‐infected patients remain suboptimal. Elimination of cccDNA is major challenge for future therapies, and new molecules such as NTCP, Toll‐like receptor (TLR)7 agonist (GS9620) and cyclophilin have emerged as potential targets for preventing HBV entry and replication. Other than these, HBV cccDNA elimination is the major target for future therapies.     

Advances in immunomodulating therapy of HBV infection

Patients with chronic hepatitis B virus (HBV) infection have a higher risk of developing liver cirrhosis and hepatocellular carcinoma. Interferon-alpha, lamivudine and adefovir dipivoxil are the three approved treatment for chronic HBV infection and offers the only means of preventing the development of these complications. However, the efficacy of these agents, in terms of loss of Hepatitis B e antigen with or without seroconversion to Hepatitis B e antibody, normalization of serum alanine transaminase levels, loss of serum HBV DNA, and improvement in liver histology can only be achieved in 20-30% of those treated. Long-term treatment with either lamivudine or adefovir dipivoxil can result in the development of drug resistant mutants leading to an increased length of treatment with additional nucleoside analogues. These limitations of the current antiviral therapies underline the need for alternative therapies. Specific and nonspecific immunotherapeutic strategies to restore effective virus-specific T cell responses in those with chronic HBV infection offers an interesting alternative approach. These immunotherapeutic therapies include the adoptive transfer of HBV immunity, pegylated interferon and therapeutic vaccine therapies.     

32例慢性乙型肝炎患者HBV P区的多位点耐药突变分析

目的 深入了解核苷(酸)类似物对乙型肝炎病毒基因组P区耐药性突变的影响,分析其对该区诱导耐药突变的作用.方法 对服用核苷(酸)类似物并且发生病毒学突破的患者,采用PCR产物直接测序法,进行HBV基因组P区耐药性基因测序分析.结果 发现P区可出现多点耐药突变,导致临床上发生交叉耐药和多重耐药.结论 应选用高耐药基因屏障的药物进行初始抗病毒治疗.对长期服用核苷(酸)类似物的患者,应定期监测HBV DNA,以便早期发现病毒学突破并及时干预.

Abstract：

Objective In order to deeply understand the effects of nucleoside analogues to HBV DNA polymerase area, which initiate a state of drug resistance due to HBV genome mutation. Methods Using PCR product direct sequencing method to test the gene sequence of P area of HBV genome of the patients who taking nucleoside analogues and showing signs of virologic breakthrough. Results More resistance mutations can be find in HBV DNA polymerase area,which causing clinically cross drug resistance and multiple resistance. Conclusion We should choose higher genetic barrier for the initial treatment. And the patients long-term using of nucleoside analogues, should be regularly monitored serum HBV DNA level, in order for early detection of virological breakthrough and timely intervention.     

32例慢性乙型肝炎患者HBV P区的多位点耐药突变分析

目的 深入了解核苷（酸）类似物对乙型肝炎病毒基因组P区耐药性突变的影响,分析其对该区诱导耐药突变的作用.方法 对服用核苷（酸）类似物并且发生病毒学突破的患者,采用PCR产物直接测序法,进行HBV基因组P区耐药性基因测序分析.结果 发现P区可出现多点耐药突变,导致临床上发生交叉耐药和多重耐药.结论 应选用高耐药基因屏障的药物进行初始抗病毒治疗.对长期服用核苷（酸）类似物的患者,应定期监测HBV DNA,以便早期发现病毒学突破并及时干预.     

Molecular and clinical aspects of hepatitis D virus infections

Hepatitis D virus (HDV) is a defective virus with circular, single-stranded genomic RNA which needs hepatitis B virus (HBV) as a helper virus for virion assembly and infectivity. HDV virions are composed of a circular shape HDV RNA and two types of viral proteins, small and large HDAgs, surrounded by HBV surface antigen (HBsAg). The RNA polymerase II from infected hepatocytes is responsible for synthesizing RNAs with positive and negative polarities for HDV, as the virus does not code any enzyme to replicate its genome. HDV occurs as co-infection or super-infection in up to 5% of HBsAg carriers. A recent multi-center study highlighted that pegylated interferon α-2a (PEG-IFN) is currently the only treatment option for delta hepatitis. Nucleotide/nucleoside analogues, which are effective against HBV, have no relevant effects on HDV. However, additional clinical trials combining PEG-IFN and tenofovir are currently ongoing. The molecular interactions between HDV and HBV are incompletely understood. Despite fluctuating patterns of HBV viral load in the presence of HDV in patients, several observations indicate that HDV has suppressive effects on HBV replication, and even in triple infections with HDV, HBV and HCV, replication of both concomitant viruses can be reduced. Additional molecular virology studies are warranted to clarify how HDV interacts with the helper virus and which key cellular pathways are used by both viruses. Further clinical trials are underway to optimize treatment strategies for delta hepatitis.     

Anti-hepatitis B activity of isoquinoline alkaloids of plant origin

Hepatitis B virus (HBV) is the causative agent of B-type hepatitis in humans, a vaccine-preventable disease. Despite the availability of effective vaccines, globally, 2 billion people show evidence of past or current HBV infection, of which 350 million people are persistently infected, with an estimated annual increase of 1 million. There is no cure for chronic HBV infections, which are associated with cirrhotic liver failure and with an increased risk of developing hepatocellular carcinoma. Hepatitis antiviral research has focused primarily on the development of inhibitors of viral polymerase through the use of nucleoside analogues. Therefore, there is an urgent need for the development of non-nucleoside compounds to be used as an alternative or to complement the current therapy. To address this need, 18 isoquinoline alkaloids were evaluated for their potential antiviral activity against HBV in vitro.     

Effect of acyclovir on the uptake of 131I-labelled 1-(2'fluoro-2'-deoxy-beta-D-arabinofuranosyl)-5-iodouracil in herpes infected cells

Selective uptake of nucleoside analogues by herpes simplex virus infected cells may serve as the basis for a specific non-invasive diagnostic test for herpes simplex encephalitis. We have examined the effect of acyclovir on the selective uptake of [131I] 1-(2'-fluoro-2'-deoxy-beta-D-arabinofuranosyl)-5-iodouracil in herpes simplex virus infected primary rabbit kidney cells. Infected cells treated with acyclovir continued to concentrate [131I] 1-(2'-fluoro-2'-deoxy-beta-D-arabinofuranosyl)-5-iodouracil for up to 24 h after the addition of the antiviral agent. These results indicated that therapy with acyclovir for as long as 24 h would not prevent the selective trapping of nucleoside analogues. This has important implications for the use of nucleoside analogues in diagnostic brain scans to detect herpes simplex encephalitis.     

HIV/HBV Co-Infections: Epidemiology, Natural History, and Treatment: A Review Article

Hepatitis B virus (HBV) infection, one of the major health priorities, accounts approximately for 350 million chronic cases and a global total of 33 million people were living with human immunodeficiency virus (HIV) in the world.Co-infection with HIV and the HBV presents a significant challenge to health care providers, with different prevalence rates in different parts of the world. It is important to screen all HIV infected individuals for HBV infection and reverse. Infection with HBV becomes more violent in patients co-infected with human immunodeficiency syndrome. HIV/HBV co-infected individuals are at increased risk of chronic hepatitis, cirrhosis, and hepatocellular carcinoma, and of experiencing HAART toxicity. In this review, the latest statistics on epidemiology of HIV, HBV and their co-infection has been presented along with prominent characteristics of HBV. Transmission routes which are the common between HBV and HIV are described and the most important ones are described according to the regional and age features. Also, there is a series of actions being performed once HBV infections occur to prevent HIV or to diagnose if the HBV-infected individuals are also infected with HIV. As in treatment case, some of the frequent treatment methods including applying interferon and using nucleoside and nucleotide analogues have been discussed. Finally, we would explain the new recommendations for treating patients who were co-infected with HBV and HIV, including staging HBV and HIV treatment, based on the stage of each disease. It also outlines the optimal treatment options, whether the patient is treated for HBV first, HIV first, or HIV and HBV together.     

Mother‐to‐child transmission of HBV: review of current clinical management and prevention strategies

Mother‐to‐child transmission (MTCT) of HBV is responsible for approximately half of the HBV transmission routes and continues to be a challenging problem worldwide. Even after the development of effective vaccines and clear World Health Organization guidelines toward HBV several decades ago, 1–9% newborns of HBV‐carrying mothers still acquire HBV in early life as a result of in utero infection. The prevention of MTCT is of high importance, because chronically infected individuals function as a reserve for sustained HBV transmission, and 25% of them can develop asymptomatic liver cirrhosis and hepatocellular carcinoma. In this article, we review the canonical and novel HBV infection routes/mechanisms, influencing factors, diagnostic criteria, and interruption strategies for HBV MTCT. The preventative strategy of HBV MTCT has evolved from routine postpartum HB immune globulin (HBIG) plus HB vaccine schedules to administration of HBIG or nucleoside analogs during pregnancy and minimizing the exposure of maternal body fluids to the newborn during delivery. Copyright © 2014 John Wiley & Sons, Ltd.     

阿德福韦酯治疗慢性乙型病毒性肝炎96周疗效观察

目的 观察阿德福韦酯治疗慢性乙型病毒性肝炎患者96周的临床疗效.方法 选取慢性乙型病毒性肝炎患者80例,予阿德福韦酯(1mg/d)抗病毒治疗;服药12周时行HBV DNA检测,无早期应答者(病毒载量下降<2 log10拷贝/ml)予改用其他核苷类药物.疗程96周,观察血清转氨酶(ALT)复常率、HBV DNA阴转率、HBeAg消失率和HBeAg血清转换率.结果 61例有早期应答患者在治疗第96周时ALT复常率达85.25%(52/61),HBV DNA阴转率为95.08%(58/61),HBeAg消失率为51.52%(17/33),而HBeA8血清转换率为42.42%(14/33);治疗至96周时有2例发生病毒学反弹.19例于12周时因无早期应答而改用其他核苷类似物患者,96周时的ALT复常率为57.89%(11/19),HBV DNA阴转率为68.42%(13/19),HBeAg消失率及HBeAg血清转换率均为58.33%(7/12).结论 阿德福韦酯对慢性乙型肝炎患者能有效抑制HBV复制,长期服用有较好疗效;对无早期应答病例及早换药有助提高疗效.     

阿德福韦酯治疗慢性乙型病毒性肝炎96周疗效观察

目的 观察阿德福韦酯治疗慢性乙型病毒性肝炎患者96周的临床疗效.方法 选取慢性乙型病毒性肝炎患者80例,予阿德福韦酯(1mg/d)抗病毒治疗;服药12周时行HBV DNA检测,无早期应答者(病毒载量下降<2 log10拷贝/ml)予改用其他核苷类药物.疗程96周,观察血清转氨酶(ALT)复常率、HBV DNA阴转率、HBeAg消失率和HBeAg血清转换率.结果 61例有早期应答患者在治疗第96周时ALT复常率达85.25%(52/61),HBV DNA阴转率为95.08%(58/61),HBeAg消失率为51.52%(17/33),而HBeA8血清转换率为42.42%(14/33);治疗至96周时有2例发生病毒学反弹.19例于12周时因无早期应答而改用其他核苷类似物患者,96周时的ALT复常率为57.89%(11/19),HBV DNA阴转率为68.42%(13/19),HBeAg消失率及HBeAg血清转换率均为58.33%(7/12).结论 阿德福韦酯对慢性乙型肝炎患者能有效抑制HBV复制,长期服用有较好疗效;对无早期应答病例及早换药有助提高疗效.     

阿德福韦酯治疗慢性乙型病毒性肝炎96周疗效观察

目的 观察阿德福韦酯治疗慢性乙型病毒性肝炎患者96周的临床疗效.方法 选取慢性乙型病毒性肝炎患者80例,予阿德福韦酯（1mg/d）抗病毒治疗;服药12周时行HBV DNA检测,无早期应答者（病毒载量下降〈2 log10拷贝/ml）予改用其他核苷类药物.疗程96周,观察血清转氨酶（ALT）复常率、HBV DNA阴转率、HBeAg消失率和HBeAg血清转换率.结果 61例有早期应答患者在治疗第96周时ALT复常率达85.25%（52/61）,HBV DNA阴转率为95.08%（58/61）,HBeAg消失率为51.52%（17/33）,而HBeA8血清转换率为42.42%（14/33）;治疗至96周时有2例发生病毒学反弹.19例于12周时因无早期应答而改用其他核苷类似物患者,96周时的ALT复常率为57.89%（11/19）,HBV DNA阴转率为68.42%（13/19）,HBeAg消失率及HBeAg血清转换率均为58.33%（7/12）.结论 阿德福韦酯对慢性乙型肝炎患者能有效抑制HBV复制,长期服用有较好疗效;对无早期应答病例及早换药有助提高疗效.     

Induction of micronuclei in mouse bone marrow cells: an evaluation of nucleoside analogues used in the treatment of AIDS

Various nucleoside analogues are being used or are being considered for use as therapeutic drugs to inhibit replication of the HTLV-III/LAV virus in infected human cells. Here, the ability of seven nucleoside analogues, a combination of two analogues, and two other therapeutic compounds to induce genotoxic and cytotoxic damage in vivo was evaluated in the mouse bone marrow micronucleus test. Using a 3-consecutive-day oral treatment protocol, almost all of the test chemicals induced a significant increase in the frequency of micronucleated polychromatic erythrocytes (MN-PCE) in male B6C3F1 mice, ranked in decreasing potency as 6-thioguanine greater than Cytarabine HCl greater than 3'-azido-3'-deoxythymidine (AZT)/2',3'-dideoxycytidine combination = AZT greater than Ribavirin = 2',3'-didehydro-3'-deoxythymidine greater than 2',3'-dideoxyadenosine = 2',3'-dideoxycytidine. The frequency of MN-PCE was not increased significantly by treatment with 2',3-dideoxyinosine (DDI) or pentamidine isethionate (PI). The differential ability of AZT and DDI to induce MN in mouse bone marrow was verified from peripheral blood smears prepared from subchronic (90 day) oral studies. The lack of genotoxic activity by DDI was route-specific since, when tested by intraperitoneal injection, a small but significant increase in MN-PCE was observed. A number of these chemicals induced a significant depression in erythropoiesis. However, there was not a significant correlation between the increase in MN-PCE and the depression in the percentage of PCE. This lack of a correlation suggests that factors other than DNA damage may contribute to the inhibition in the rate of erythropoiesis. The presence of increased levels of micronuclei in bone marrow PCE following treatment with various nucleoside analogues suggests that intrinsic genotoxic activity in mammalian cells should be one factor considered during drug selection for AIDS therapy.     

比较α-干扰素不同联合治疗方案对儿童HBeAg阳性慢性乙型肝炎的疗效

目的评估两种不同的α-干扰素联合治疗对儿童HBeAg阳性慢性乙型肝炎的临床疗效。方法选择HBeAg阳性慢性乙型肝炎儿童120例,随机分为3组,每组各40例:第1组(A组)为α-干扰素(IFN-α)组;第2组(B组)为IFN-α 拉米夫定(LAM)组。第3组(C组)为α-干扰素(IFN-α) 乙肝疫苗组。其中干扰素疗程6个月,拉米夫定疗程6个月,所有病例均观察至12个月。结果治疗结束时丙氨酸转氨酶(ALT)复常率3组无差异。治疗6个月和12个月时B组HBeAg阴转率和HBV DNA的阴转率明显高于A组和B组,差异有统计学意义(P<0.05)。结论α-干扰素与拉米夫定联合治疗对HBeAg阳性慢性乙型肝炎儿童的病毒学应答(VR)疗效明显优于单用α-干扰素组和α-干扰素 乙肝疫苗组。