Inhibitors of the Hepatitis C Virus Polymerase; Mode of Action and Resistance

The hepatitis C virus (HCV) is a pandemic human pathogen posing a substantial health and economic burden in both developing and developed countries. Controlling the spread of HCV through behavioural prevention strategies has met with limited success and vaccine development remains slow. The development of antiviral therapeutic agents has also been challenging, primarily due to the lack of efficient cell culture and animal models for all HCV genotypes, as well as the large genetic diversity between HCV strains. On the other hand, the use of interferon-α-based treatments in combination with the guanosine analogue, ribavirin, achieved limited success, and widespread use of these therapies has been hampered by prevalent side effects. For more than a decade, the HCV RNA-dependent RNA polymerase (RdRp) has been targeted for antiviral development. Direct acting antivirals (DAA) have been identified which bind to one of at least six RdRp inhibitor-binding sites, and are now becoming a mainstay of highly effective and well tolerated antiviral treatment for HCV infection. Here we review the different classes of RdRp inhibitors and their mode of action against HCV. Furthermore, the mechanism of antiviral resistance to each class is described, including naturally occurring resistance-associated variants (RAVs) in different viral strains and genotypes. Finally, we review the impact of these RAVs on treatment outcomes with the newly developed regimens.     

Immune responses against hepatitis C virus genotype 3a virus-like particles in mice: A novel VLP prime-adenovirus boost strategy

Chronic hepatitis C virus (HCV) infection represents a major health threat to global population. In India, approximately 15–20% of cases of chronic liver diseases are caused by HCV infection. Although, new drug treatments hold great promise for HCV eradication in infected individuals, the treatments are highly expensive. A vaccine for preventing or treating HCV infection would be of great value, particularly in developing countries. Several preclinical trials of virus-like particle (VLP) based vaccine strategies are in progress throughout the world. Previously, using baculovirus based system, we have reported the production of hepatitis C virus-like particles (HCV-LPs) encoding structural proteins for genotype 3a, which is prevalent in India. In the present study, we have generated HCV-LPs using adenovirus based system and tried different immunization strategies by using combinations of both kinds of HCV-LPs with other genotype 3a-based immunogens. HCV-LPs and peptides based ELISAs were used to evaluate antibody responses generated by these combinations. Cell-mediated immune responses were measured by using T-cell proliferation assay and intracellular cytokine staining. We observed that administration of recombinant adenoviruses expressing HCV structural proteins as final booster enhances both antibody as well as T-cell responses. Additionally, reduction of binding of VLP and JFH1 virus to human hepatocellular carcinoma cells demonstrated the presence of neutralizing antibodies in immunized sera. Taken together, our results suggest that the combined regimen of VLP followed by recombinant adenovirus could more effectively inhibit HCV infection, endorsing the novel vaccine strategy.     

河南省1例柬埔寨输入登革热病例的病原分子分型与全基因序列分析

目的鉴定河南省1例来自柬埔寨的登革热输入性病例的登革病毒(dengue virus,DENV)血清型和基因型及其序列特征和传播来源。方法患者血液标本来源于2019年国家疾病监测系统网络直报的登革热疑似病例。样品经快速检测DENV NS1抗原和IgM/IgG抗体,再提取血清中核酸,应用荧光RT-PCR法进行DENV血清型鉴定,同时用Vero和BHK-21细胞对血清标本进行病毒分离培养,阳性培养物扩增全基因组序列,进行序列系统进化分析。结果该病例实验室确诊为DENV 1型感染,并从血清标本中分离到病毒株,测序后拼接成全长10670 nt的全基因组序列,经系统进化分析,该病毒株属于DENV 1型基因Ⅰ型,与东南亚流行株具有较高同源性和较近亲缘关系。结论2019年河南省来自柬埔寨的输入性病例的病原体为DENV 1型基因I型,此为近年来东南亚输入我国的常见血清型和基因型。     

直接抗病毒药物治疗丙型肝炎合并透析患者的临床应用

丙型肝炎病毒（HCV）感染在慢性肾功能不全患者中较常见，尤其是在进行透析的患者中，HCV感染较普通患者的风险极大增加，同时还会导致肝细胞癌及肝硬化的发病率明显升高。近年来直接抗病毒药物（DAAs）在慢性丙型肝炎的治疗中取得了较好的疗效及安全性，本文通过总结DAAs在丙型肝炎合并透析患者中的应用进展，发现对于基因1~6型HCV合并透析患者，推荐使用G/P方案；由于索磷布韦（SOF）经肾脏代谢，在重度肾损害人群中的血药浓度较高，因此SOF组合方案并不推荐用于丙型肝炎合并透析患者的治疗。     

Auditory findings associated with Zika virus infection: an integrative review

IntroductionPossible associations between Zika virus infection and hearing loss were observed during the epidemic in the Americas.ObjectiveTo describe the auditory alterations, pathogenesis and recommendations for follow-up in individuals with prenatal or acquired Zika virus infection.MethodsBibliographic research conducted in March/2018–April/2019 at the main available databases. Article selection, data extraction and quality evaluation were carried out by two independent reviewers. Studies containing auditory evaluation of patients with congenital or acquired Zika virus infection; and/or hypotheses or evidences on the pathophysiology of auditory impairment associated with Zika virus; and/or recommendations on screening and follow-up of patients with auditory impairment by Zika virus were included.ResultsA total of 27 articles were selected. Sensorineural and transient hearing loss were reported in six adults with acquired Zika virus infection. Of the 962 studied children, 482 had microcephaly and 145 had diagnostic confirmation of Zika virus; 515 of the 624 children with auditory evaluation performed only screening tests with otoacoustic emissions testing and/or automated click-stimuli auditory brainstem response testing. Studies in prenatally exposed children were very heterogeneous and great variations in the frequency of altered otoacoustic emissions and automated click-stimuli auditory brainstem response occurred across the studies. Altered otoacoustic emissions varied from 0% to 75%, while altered automated click-stimuli auditory brainstem response varied from 0% to 29.2%. Sensorineural, retrocochlear or central origin impairment could not be ruled out. One study with infected mice found no microscopic damage to cochlear hair cells. Studies on the pathogenesis of auditory changes in humans are limited to hypotheses and recommendations still include points of controversy.ConclusionThe available data are still insufficient to understand the full spectrum of the involvement of the auditory organs by Zika virus, the pathogenesis of this involvement or even to confirm the causal association between auditory involvement and virus infection. The screening and follow-up recommendations still present points of controversy.     

Expression of TRIM22 mRNA in chronic hepatitis C patients treated with direct-acting antiviral drugs

Hepatitis C is a global public health problem, and Pakistan is the second largest country in the globe with highest prevalence rate of hepatitis C virus (HCV). Until 2014, pegylated interferon (PEG-IFN) plus ribavirin (RBV) has been the standard therapy for HCV, however, owing to its adverse side effects and very low sustained virologic response (SVR) rates therapeutics trend is shifted toward direct-acting antivirals. Tripartite motif containing 22 (TRIM22) is a dynamic antiviral protein that can inhibit multiple viruses in vivo. Expression of TRIM22 mRNA has been linked to outcome of PEG-IFN and ribavirin therapy, where its higher expression leads to rapid virus clearance. However, in terms of therapy with direct-acting antiviral (DAA) or double DAA, impact of TRIM22 expression is largely unknown. These new drugs show more than 90% of SVR rates and lesser side effects and have proven to be better than IFN therapy. Endogenous IFN system suppresses various pathogens through the induction of antiviral effectors termed as interferon-stimulating genes (ISGs). We have studied the expression levels of one of these antiviral effectors, TRIM22 in response to sofosbuvir (SOF) and daclatasvir (DAC) in combination with RBV, using quantitative PCR in the peripheral blood mononuclear cells (PBMCs) of HCV-infected patients. We have observed sustained virus clearance in more than 90% of patients treated with DAA and double DAA and have seen the expression of TRIM22 to be higher in patients who attained SVR as compared to the untreated patients. We have also observed downregulation of TRIM22 in patients who failed to attain rapid virus clearance, and upregulation in those who achieved rapid clearance of virus. Genetic factors that determine the lower TRIM22 expression in these patients are needed to be explored that may also play a role in lower response to anti-HCV therapy. Endogenous IFN system and effects of antiviral proteins in response to DAA therapy is needed to be studied in order to better understand the host response toward these drugs to make them more effective.     

基于《温疫论》理论探讨新冠肺炎的辨证施治方法

2019年12月我国武汉爆发新型冠状病毒肺炎(新冠肺炎),具有较强的传染性和流行性,属于中医学"瘟疫"范畴,严重威胁人类的生命健康。面对这一突发的公共卫生事件,该文基于《温疫论》理论,从临床实际出发,对新冠肺炎的发病特点、传变以及辨证论治进行了解析。根据此次疫情的特点,新冠肺炎的病因为感受"戾气",病机为疫毒遏湿,其传变遵循《温疫论》"表里九传"规律,可分为顺传与逆传,病程具有一定的规律性与阶段性。初期邪伏膜原、疫毒遏湿,应开达膜原、祛湿化浊、宣透疏利;中期病邪可顺传于表,此时应当使用辛凉解表之剂,通过战汗透邪,使邪随汗出,若湿毒入里化热,致肺络受损,腑气不通,里实热结,当通腑泻热,攻下逐邪,给邪以出路;若失治、误治、病邪太过,可致病邪内陷心包,造成神昏谵语、躁扰不宁、四肢厥逆、脉微欲绝等内闭外脱的危重表现,治疗上注意攻补兼施,开闭固脱;恢复期,由于余邪未尽,且热病易伤阴耗气,治疗上不仅要预防余邪反复,更要滋阴补血,恢复正气。在疾病治疗过程中,吴又可提出"祛邪为第一要义、忌妄汗下法、顾护脾胃"三大法则。《温疫论》对"瘟疫"的病因病机、传变和辨证施治有着系统的认识,为后代战胜历次瘟疫提供了宝贵经验,这对于此次新冠肺炎的防治同样具有重要的指导意义。