病毒性肝炎均属消化道传染病吗?

答：初中生物第二册工21页在叙述消化道传染病时,例举了病毒性肝炎,这往往给人一个错觉,病毒性肝炎均属消化道传染病。这样理解是不对的,因为按目前人们对病毒性肝炎的认识,它可分为五种类型,即甲型、乙型、丙型、丁型、戊型。其中甲型和戊型病毒型肝炎是通过饮水和食物传播的属消化道传染病。乙型和丁型病毒性肝炎是通过血液和血液制品传播的,应属血液传染病;丙型病毒性肝炎传播途径是血液、血液制品、皮肤损伤和生活接触,因此,它既属血液传染病又属体表传染病。所以,病毒性肝炎的分类,不能一概而定,应视类型的不同而有所不同…     

病毒性肝炎树鼩动物模型研究与建模策略

病毒性肝炎是由肝炎病毒引起的肝脏疾病。在我国,病毒性肝炎高度流行,其中又以乙型肝炎病毒(Hepatitis B virus,HBV)和丙型肝炎病毒(Hepatitis C virus,HCV)危害较大。动物模型是研究疾病感染与发病机制,进行药物与疫苗研究的必要工具。目前病毒性肝炎实验动物模型的研究已取得长足的发展,主要集中于病毒在动物体内的感染特性及发病规律方面。本文仅就病毒性肝炎动物模型,尤其乙型、丙型肝炎树鼩动物模型的研究及建模策略进行综述。     

丙型肝炎病毒分子生物学研究进展

丙型肝炎病毒(HCV)是经血源传播的一类肝炎病毒。1989年美国Chiron公司Choo等率先将HCV cDNA克隆成功,使HCV成为第一个利用分子生物学技术而发现的病毒。近两年来,HCV研究的进展十分迅速,已成为病毒性肝炎研究领域中的一个热点。本文就HCV分子生物学的研究进展作一综述。     

消化道传播病毒性肝炎研究进展

病毒性肝炎是由多种不同肝炎病毒引起的,以肝脏损害为主要表现,具有广泛流行性和严重传染性的一类疾病,严重危害人类健康,是我国目前重大的公共卫生问题之一。迄今鉴定出的具有明确致病性的肝炎病毒主要是甲型肝炎病毒(HAV)、乙型肝炎病毒(HBV)、丙型肝炎病毒(HCV)、丁型肝炎病毒(HDV)和戊型肝炎病毒(HEV),分别引起甲、乙、丙、丁、戊型肝炎。病毒性肝炎按传播途径的不同可以分为两类,一类是经肠道外传播的病毒性肝炎,包括乙、丙、丁型肝炎;另一类是经肠道(即消化道)传播的肝炎病毒,包括甲肝和戊肝,其发病有季节性,可呈暴发流行。本文旨在对经消化道传播的病毒型肝炎(甲肝、戊肝)的病原学、流行病学特征及其影响因素、控制和预防作一综述,以期对其流行和科学防控研究提供参考。     

慢性病毒性肝炎研究进展

近年,慢性病毒性肝炎研究领域有较大进展,慢性乙型肝炎病毒（HBV）感染,虽然有了应用广泛、历史较久、且效果较好的疫苗,但迄今仍是世界范围肝硬化和肝癌的主要诱因。传染途径可经产道、性接触和非肠道途径（包括静脉吸毒、血制品等）。成年病人有少有变慢性,但一岁以下患儿90％变成慢性肝炎。慢性肝损伤的临床表现可以是轻微的炎症重到晚期肝硬化,程度不等。α干扰素（IFNα）是治疗活动性肝炎的产宰药物,单核苷酸类药物（lamivudine和adefovir）也具有同样的疗效。晚期肝病和肝癌患者可进行移植,但异常伴发移植物的感染。乙型肝炎免疫球蛋白和新型抗病毒药物联合应用,可降低移植物感染的严重性。丙型肝炎病毒（HCV）在20世纪后期感染了大约1％的世界人口。这中RNA病毒非经口传播,绝大多数病人变成慢性肝炎,约20％逐渐演变成肝硬化或肝癌。用IFNα和病毒唑（Ribavirin）联合治疗,约40％病人的病理表现有所改善。肝移植对某些病例是适宜的,但移植物感染仍是悬而未决的问题,新发现的庚型肝炎病毒（HGV）和TT病毒目前认为并不引起严重的肝损害。     

细胞异常信号转导:丙型肝炎病毒致病新模式

丙型肝炎病毒(HCV)感染除可致丙型肝炎外,尚可引起Ⅱ型冷球蛋白血症及非霍奇金病恶性淋巴瘤等.同为HCV感染,但却为何表现以不同细胞(肝细胞、淋巴细胞)病变为特征的疾病形式?目前认为此因HCV在不同类型细胞内引发信号转导途径不同所致,因而继"病毒增殖侵害"与"宿主免疫病理反应"的致病机制之后,又提出了细胞异常信号转导为HCV致病模式的观点.     

探寻新型HCV同源病毒的自然宿主

丙型肝炎病毒(hepatitis C virus,HCV)感染是一个世界性的公共卫生问题,该病毒感染后可引起急、慢性肝炎。由于HCV的宿主范围较窄,一直未找到合适的动物模型来研究该病毒的致病机制、免疫预防等,至今也无证据表明动物源的HCV同源病毒可能跨种传播给人类。最近,研究者在小型野生动物(如啮齿类动物、蝙蝠)和家养动物(如犬、马、牛)中相继发现了新型HCV同源病毒(HCV样病毒和GBV样病毒),这些病毒分别属于丙型肝炎病毒属(hepacivirus)或持续性G病毒属(pegivirus),研究这些病毒的基因组结构和生物学特征有助于HCV的起源及其致病机制和免疫等研究。本综述从HCV基本特征、相关病毒谈起,着重介绍新型HCV同源病毒,并探寻其自然宿主,进而讨论了人类重要病原之一HCV的起源问题。     

丙型肝炎病毒致病新模式: 包膜蛋白2对MAPK/ERK途径的激活

细胞信号转导异常可揭示人类疾病发生的本质, 一些病毒的致病机制即源于其蛋白所致宿主细胞内信号转导的紊乱. 丙型肝炎病毒(HCV)感染是引起人类严重肝脏疾病的主要病因, 但致病机制尚未明确. HCV包膜蛋白2(E2蛋白)能介导病毒吸附并结合至靶细胞表面, 此乃HCV感染的前提及首发事件. 推测HCV E2蛋白经与其受体(人CD81)的相互作用而将病毒感染信号传递至宿主细胞内, 使细胞增殖和分化异常, 从而导致感染细胞发生早期病变. 为进一步验证此致病机制, 研究了HCV E2蛋白等诸因素对差异表达人CD81的U937, Molt-4细胞内MAPK/ERK途径的影响, 结果表明, HCV E2蛋白可特异性激活细胞内MAPK/ERK途径, 而HCV E2单抗、CD81单抗、 慢性HCV感染患者血清或MAPK/ERK途径上游MEK1的抑制剂(PD98059)均不同程度地减弱或抑制HCV E2蛋白对MAPK/ERK的激活. 此外, PD98059尚可抑制HCV E2蛋白对MAPK/ERK途径下游转录因子Elk-1的活化. 研究认为, HCV E2蛋白经其相应受体引发的宿主细胞跨膜信号转导异常很可能是HCV的致病机制之一.     

锁核酸SPC3649在HCV抗感染治疗中的研究进展

丙型肝炎病毒(HCV)是由约9.6kb个核苷酸组成的单股正链RNA病毒,属于黄病毒科丙型肝炎病毒属,被分为7个基因型及若干亚型。丙型肝炎是由HCV感染引起的常见血液传播型疾病,全球约有1.8亿人感染,引起慢性肝炎、肝硬化、肝癌。至今没有针对HCV的保护性疫苗,目前批准的标准治疗方式主要是聚乙二醇-干扰素(PEG-IFN)和利巴韦林(RBV)的联合疗法。目前这种疗法对不同基因型的感染患者的作用效果差异很大,对HCV基因2型及3型的患者,80%可以获得持续的病毒学应答反应(SVR),然而     

哪些病原体感染与优生优育有关?

问：哪些病原体感染与优生优育有关？ 答：随着人们对母婴保健关注程度的提高,宫内感染造成的影响越来越多的引起了人们的重视。许多研究均已证实,孕期感染的一些病原体不仅威胁母体健康,还可以可通过垂直传播途径,造成胎儿感染。许多病原体与早产及流产的发生相关......     

Clinical and epidemiologic characteristics of hepatitis C in a gastroenterology/hepatology practice in Ottawa.

OBJECTIVE: To examine the clinical and epidemiologic features of hepatitis C virus (HCV) infection in a gastroenterology/hepatology practice in Ottawa. DESIGN: Retrospective chart review. PATIENTS: Sixty-three consecutive patients found to be anti-HCV positive. Their charts were analysed with respect to risk factors, history of hepatitis, serum aspartate aminotransferase (AST) levels and the presence of hepatitis B markers. The long-term sexual partners of 29 patients agreed to undergo HCV antibody testing. RESULTS: Of the patients 48 (76%) had been exposed to HCV parenterally: 27 used intravenous drugs, and 21 had received blood or blood products. Eleven patients did not have any known risk factor (sporadic infection), but eight of them had lived in countries where hepatitis C may be more prevalent; the other three had locally acquired infection. The mean serum AST level at the first visit was 140 (normally less than 40) IU/L. At least one hepatitis B marker was identified in 33% of the patients. None of the sexual partners who were tested were anti-HCV positive. CONCLUSION: Most cases of hepatitis C in Ottawa are acquired through parenteral exposure; sexual transmission is rare. Sporadic infection in the Ottawa region is rare but may be more common in people from countries with a higher prevalence rate of hepatitis C. Most cases of hepatitis C are asymptomatic.     

Investigating the endemic transmission of the hepatitis C virus

The hepatitis C virus (HCV) infects at least 3% of people worldwide and is a leading global cause of liver disease. Although HCV spread epidemically during the 20th century, particularly by blood transfusion, it has clearly been present in human populations for several centuries. Here we attempt to redress the paucity of investigation into how long-term endemic transmission of HCV has been maintained. Such transmission not only represents the 'natural' route of infection but also contributes to new infections today. As a first step, we investigate the hypothesis that HCV can be mechanically transmitted by biting arthropods. Firstly, we use a combined bioinformatic and geographic approach to build a spatial database of endemic HCV infection and demonstrate that this can be used to geographically compare endemic HCV with the range distributions of potential vector species. Second, we use models from mathematical epidemiology to investigate if the parameters that describe the biting behaviour of vectors are consistent with a proposed basic reproduction number (R0) for HCV, and with the sustained transmission of the virus by mechanical transmission. Our analyses indicate that the mechanical transmission of HCV is plausible and that much further research into endemic HCV is needed.     

HIV/HCV co-infection: natural history

HIV and HCV share common transmission pathways, but HCV is more efficiently transmitted through blood than with sexual exposure. Thus HCV coinfection is frequent in HIV seropositives, mainly in those with history of injection drug use and/or transfusion. HIV coinfection increases HCV replication rate, the rate of HCV vertical transmission and accelerates the course of hepatitis C towards cirrhosis and hepatocellular carcinoma. The evidence of an effect of HCV on HIV disease progression is less convincing. The results of several studies suggest that HCV coinfection does not hasten the progression of HIV infection towards AIDS. However two recent studies showed that HCV coinfection is independently associated with a lower restoration of CD4 counts during combination antiretroviral treatment. However this finding should be confirmed by additional studies.     

Innate Immune Function in Placenta and Cord Blood of Hepatitis C – Seropositive Mother-Infant Dyads

Vertical transmission accounts for the majority of pediatric cases of hepatitis C viral (HCV) infection. In contrast to the adult population who develop persistent viremia in ∼80% of cases following exposure, the rate of mother-to-child transmission (2–6%) is strikingly low. Protection from vertical transmission likely requires the coordination of multiple components of the immune system. Placenta and decidua provide a direct connection between mother and infant. We hypothesized that innate immune responses would differ across the three compartments (decidua, placenta and cord blood) and that hepatitis C exposure would modify innate immunity in these tissues. The study was comprised of HCV-infected and healthy control mother and infant pairs from whom cord blood, placenta and decidua were collected with isolation of mononuclear cells. Multiparameter flow cytometry was performed to assess the phenotype, intracellular cytokine production and cytotoxicity of the cells. In keeping with a model where the maternal-fetal interface provides antiviral protection, we found a gradient in proportional frequencies of NKT and γδ-T cells being higher in placenta than cord blood. Cytotoxicity of NK and NKT cells was enhanced in placenta and placental NKT cytotoxicity was further increased by HCV infection. HCV exposure had multiple effects on innate cells including a decrease in activation markers (CD69, TRAIL and NKp44) on NK cells and a decrease in plasmacytoid dendritic cells in both placenta and cord blood of exposed infants. In summary, the placenta represents an active innate immunological organ that provides antiviral protection against HCV transmission in the majority of cases; the increased incidence in preterm labor previously described in HCV-seropositive mothers may be related to enhanced cytotoxicity of NKT cells.     

The natural course of chronic hepatitis C

Abstract: In 1988, investigators from the Chiron Company (USA) detected the non-A, non-B agent and named it hepatitis C virus (HCV). An anti-HCV antibody assay (ELISA) and subsequently confirmation tests (immunoblot and polymerase chain reaction) were developed. HCV exposure results in a chronic infection in a majority of cases. This chronic infection is associated with slowly progressive chronic liver disease. Chronic HCV infection is, like HBV, also associated with the development of hepatocellular carcinoma. Most HCV carriers are infected by parenteral routes. Intravenous drug users have the highest risk of becoming infected. Intrafamiliar spread is seen in certain parts of the world but sexual and perinatal transmission does not play an important role in spreading the infection. Antiviral therapy (alpha-interferon) in patients with chronic hepatitis C will normalize liver function tests in about 25% of the cases.     

Hepatitis C virus infection from blood and blood products

Abstract: The addition of second-generation HCV epitopes in antibody detection assays has increased the sensitivity and specificity of blood donor testing, to prevent post-transfusion hepatitis non-A, non-B (PTH-NANB), later characterized as Hepatitis C. However, it is not clear whether all HCV infectious donors are detected by second generation anti-HCV testing. Prospective studies on PTH-NANB were left with some unresolved cases. The use of second-generation anti-HCV assays in blood banks presented a problem with a relatively large number of indeterminate reactivities in supplemental assays such as RIBA-2. These indeterminate reactivities may be solved by the use of polymerase chain reaction (PCR). PCR is more and more used as an extra confirmatory assay to resolve RIBA indeterminate results on blood donors. However, a European study on the proficiency of HCV PCR in different countries revealed that only a minority of the reference laboratories perform this test faultness. Lately, third generation RIBA was developed, which was originally designed to resolve RIBA-2 indeterminate cases. RIBA-3 was shown to be more sensitive and specific in early HCV infection and blood donors than RIBA-2. Third generation anti-HCV testing will become standard practice. Some questions, however, remain unanswered. Do we miss any rare HCV infectious donors, of other genotypes, with third-generation assays, based only on the type 1 sequence of HCV? Can we improve HCV detection in the early phase of infection? What is the role of sporadic HCV transmission? How can we standardize HCV nucleic acid detection methods?     

丙型肝炎病毒受体SR-BⅠ的研究进展

丙型肝炎病毒（HCV）是经血液传播而引起急、慢性肝炎的主要致病因子之一,是导致肝硬化、肝细胞癌等终末期肝病的主要原因。位于HCV包膜E2蛋白N端的第1高变区（HVR1）,是介导E2蛋白与B族I型清道夫受体（SR-BⅠ）结合及HCV感染细胞的关键肽段。研究表明,HCV可能利用了SR-BⅠ受体的某些生理功能入侵细胞,进行细胞-细胞间传播。因此,HVR1与SR-BⅠ相互作用的研究除了能深入了解HCV吸附和入侵细胞机制,同时也为治疗和预防HCV感染提供了新的靶点。     

Hepatitis G virus (GBV-C) infection among Brazilian patients with chronic liver disease and blood donors

Background: The recently discovered hepatitis G virus (HGV) belongs, as hepatitis C virus (HCV), to the Flaviviridae family. HGV has been isolated from the serum of patients with non A-E hepatitis. However, the association of HGV with hepatitis is uncertain.Objective: To determine the HGV prevalence in blood donors and in patients with liver disease and to evaluate a possible correlation between HGV infection and liver disease.Study design: Sera from a total of 113 consecutive patients with chronic liver disease were submitted to a series of liver enzymes and function tests and analyzed for the presence of HBsAg, anti-HBs, anti-HBc, anti-HCV, HCV RNA and HGV RNA. Prevalence of HGV RNA was determined in a group of 87 blood donors.Results: Nine (10%) sera from blood donors and 15 (13%) sera from patients with chronic liver disease were HGV RNA positive. Some 28 (25%) patients were HCV RNA positive, with genotypes 1a, 1b and 3 present in 10, 12 and 5 patients, respectively. A total of 20 (18%) patients were HBsAg carriers. Five (4%) patients were double infected (one with HBV+HCV, one with HBV+HGV and three with HCV+HGV).Conclusion: The proportion (10%) of HGV-infected blood donors was very high when compared with other countries. The results did not allow to establish HGV as an etiologic agent for chronic liver disease. The parenteral route was the presumed means of HGV transmission for only one-third of the patients.     

Seroepidemiology of hepatitis C virus in Beijing, China

To investigate the seroprevalence of hepatitis C virus (HCV) in China we tested sera from healthy individuals without hepatitis and no history of parenteral blood exposure and from patients admitted to a hepatitis hospital in Beijing. Sera were tested for anti-HCV by first-generation enzyme immunoassay; selected positives were tested with two second-generation EIAs, one utilizing recombinant antigens and the other synthetic peptides. We found anti-HCV with the following frequencies: 10 of 164 (6%) individuals with no disease; 2 of 36 (5.5%) patients with acute non-A non-B hepatitis (NANBH); 26 of 39 (67%) patients with post-transfusion NANBH; 10 of 34 (29%) patients with chronic hepatitis negative for hepatitis B surface antigen (HBsAg); 3 of 30 (10%) patients with chronic HBsAg-positive hepatitis; 0 of 19 patients with acute HBsAg-positive hepatitis. Of 24 repeat-positive sera, 19 were positive by both and 4 by one second-generation tests. We conclude that hepatitis C infection is common in China, that it contributes substantially to the incidence of post-transfusion hepatitis, and that HCV plays a significant role in both acute and chronic hepatitis. Further studies are needed to extend these observations and to define the predominant routes of transmission of HCV in China.     

Influence of backward bifurcation in a model of hepatitis B and C viruses

In the 1990s, liver transplantation for hepatitis B and C virus (HBV and HCV) related-liver diseases was a very controversial issue since recurrent infection of the graft was inevitable. Significant progress has been made in the prophylaxis and treatment of recurrent hepatitis B/C (or HBV/HCV infection) after liver transplantation. In this paper, we propose a mathematical model of ordinary differential equations describing the dynamics of the HBV/HCV and its interaction with both liver and blood cells. A single model is used to describe infection of either virus since the dynamics in-host (infected of the liver) are similar. Analyzing the model, we observe that the system shows either a transcritical or a backward bifurcation. Explicit conditions on the model parameters are given for the backward bifurcation to be present. Consequently, we investigate possible factors that are responsible for HBV/HCV infection and assess control strategies to reduce HBV/HCV reinfection and improve graft survival after liver transplantation.