亚甲蓝光化学灭活对血浆丙型肝炎病毒基因组核酸降解的研究

目的研究丙型肝炎病毒(HCV)基因组核酸在亚甲蓝光化学法(methelene blue photochemistry,MB-P)灭活病毒前后的变化,在全基因组水平分析MB-P对基因组各结构区段的降解作用。方法含HCV的血浆中加入终浓度为1.0μmol/L的MB,经约30000Lux强度的荧光照射后,在不同作用时间点取样;将HCV全基因组序列分为互相重叠的8个区段,分别进行RT-PCR,分析基因组核酸的完整性;同时运用实时定量PCR(real time-PCR,RT-PCR)技术观察核酸降解的动力学变化。结果基因组各区段RT-PCR结果发现,经过不同的光照时间,HCV基因组各区段的稳定性不同,第2、4、5、6区段对MB-P作用较敏感,基因组5’端区段和3’端区段经MB-P作用后的稳定性高于基因组其它区段;RT-PCR结果显示,随着光照时间延长,可被检测到的病毒核酸拷贝数逐渐下降。结论MB-P灭活过程中HCV基因组核酸被降解,而且基因组不同区段对光化学作用的反应性不同,提示RNA降解可能是病毒灭活的重要机制;检测病毒核酸稳定性以监测病毒灭活具有一定临床实用价值。     

Neopterin levels during the early phase of human immunodeficiency virus, hepatitis C virus, or hepatitis B virus infection

BACKGROUND: A study was conducted to assess the diagnostic sensitivity of neopterin screening of blood donors with regard to the detection of window-phase specimens of human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) infection. STUDY DESIGN AND METHODS: In total, 1002 diagnostic window-phase specimens from 98 seroconversion panels (29 HIV-1, 52 HCV, and 17 HBV) were analyzed with viral antigen detection, viral nucleic acid amplification testing (NAT), and neopterin quantitation assays. The study was completed by the analysis of 92 anti-hepatitis B core antigen (HBc)-reactive and 103 alanine aminotransferase (ALT)-elevated blood donor specimens. RESULTS: A significant association between elevated neopterin concentrations and the very early phase of HIV-1 infection was found. No significant correlation could be observed between neopterin levels and the early phase of HCV or HBV infection. Neopterin concentration was not increased in specimens from blood donors with anti-HBc reactivity or ALT elevation. CONCLUSIONS: Neopterin screening of blood donors may identify window-phase cases of HIV, but not of HCV or HBV infection. The diagnostic sensitivity of neopterin screening during the HIV window phase is similar to that of the p24 antigen test. With the introduction of viral NATs in blood screening, there is no additional benefit of neopterin screening with regard to the three blood-borne viruses HIV, HCV, and HBV. Acute phases of other infectious agents, however, have been reported to be detected by neopterin enzyme-linked immunosorbent assays.     

Detection of hepatitis C virus RNA in patients with chronic hepatitis C virus infections during and after therapy with alpha interferon.

In 24 patients with hepatitic C virus (HCV) infection who participated in a randomized trial with alpha 2B interferon, HCV RNA analysis by the polymerase chain reaction with two separate primer sets was performed at weeks 0, 4, and 24 and during a follow-up period of 6 to 9 months. Prior to therapy all patients were HCV RNA positive. During therapy, HCV RNA decreased to an undetectable level (< 1 chimpanzee infectious dose per ml) in nine patients at week 4. After week 4, no additional cases of HCV RNA disappearance (< 1 chimpanzee infectious dose per ml) were observed. During follow-up, HCV RNA could not be detected in four of the six patients with a sustained alanine aminotransferase response. These results suggest the probable predictive value of HCV RNA levels for detecting the failure of therapy in an early stage of HCV infection.     

血浆中丙型肝炎病毒核酸在不同保存条件下的稳定性

目的探讨不同保存条件和时间对丙型肝炎病毒(HCV)RNA稳定性的影响。方法将22份血浆样本置于-20℃保存4周,4℃保存12d,室温(20~25℃)保存7d,反复冻融5次,采用荧光定量聚合酶链反应测定HCV RNA水平,考察HCV RNA稳定性。结果样本在-20℃保存4周HCV RNA平均下降幅度小于或等于0.14lg,±95%CI≤0.20lg;4℃保存12dHCV RNA平均下降幅度小于或等于0.39lg,4℃保存12d时95%CI下限为-0.50lg,12d时±95%CI≤0.24lg;室温保存7dHCV RNA平均下降幅度小于或等于0.40lg,室温保存7d处理组95%CI下限为-0.53lg,7d时±95%CI≤0.29lg;反复冻融5次HCV RNA平均下降幅度小于或等于0.10lg,±95%CI≤0.15lg。结论血浆样本在-20℃保存4周、4℃保存9d、室温保存5d和反复冻融5次时,对HCV RNA水平影响不明显,但4℃保存12d或室温保存7d后,RNA水平显著降低,所以应避免在这种条件和时间下保存和运输血浆。     

Hepatitis B virus,hepatitis C virus

Medical workers should have anti-HBV antibody to protect HBV infection in the hospital. If they have not anti-HBV antibody, they should receive HBV vaccination. HBV vaccination program is as follows: 10 micrograms, s.c., 0, 1, 6 months. In case of HBV contamination, 1,000 IU hepatitis B immune globulin(HBIG) and/or 10 micrograms HB vaccine should be administered judging from HBV markers of contaminated subjects and HBV load of patients. The HCV vaccine is not available. In case of HCV contamination, it is unnecessary to treat just after accident. If acute hepatitis C is evolved in those subjects during follow-up, it is recommended to treat with interferon. Eradication of HCV by interferon among patients with acute hepatitis C will be almost 100%.     

Persistent infection mechanism of GB virus C/hepatitis G virus differs from that of hepatitis C virus

OBJECTIVE: Changes in the deduced amino acid sequence of the envelope 2 (E2) region of the GB virus C/hepatitis G virus (GBV-C/HGV) were analyzed to investigate whether or not the region contributes to persistent infection with the virus. METHODS: Eight patients with acute hepatitis C and 1 patient with acute hepatitis of unknown etiology were included in the study. GBV-C/HGV RNA was detected in 6 patients, including the patient with hepatitis of unknown origin. The nucleotide sequence of the E2 region of hepatitis C virus (HCV) and GBV-C/HGV was determined by direct sequencing of polymerase chain reaction products in 5 patients with HCV infection and in 6 patients with GBV-C/HGV infection twice during the period of early infection and several months or years later in each patient. RESULTS: The mean substitution rate of the deduced amino acid sequence in the E2 region was over 100 times lower (p < 0.001) in GBV-C/HGV (0.01 +/- 0.04/month/100 sites) than in HCV (2.4 +/- 1.7/month/100 sites). The amino acid sequence of the loop domain of GBV-C/HGV-E2 did not change in any of the 6 patients. On the other hand, the sequence of the hypervariable region of HCV-E2 changed remarkably (5.9 +/- 4.3/month/100 sites). No amino acid substitution in the loop domain was observed in 7 additional patients who showed persistent GBV-C/HGV viremia for more than 2 years. CONCLUSION: These results indicate that changes in the amino acid sequence of the E2 region are not involved in the mechanism of persistent GBV-C/HGV infection.     

Prevention of mother-to-child transmission of hepatitis B virus and hepatitis C virus

About 240 million people worldwide are chronically infected with hepatitis B virus (HBV). Vertical transmission is the most important mechanism of infection persistence in endemic areas. About 150 million people worldwide are chronically infected with hepatitis C virus (HCV). Mother-to-child transmission of HCV, which occurs in 3–10% of cases, is the leading route of infection in childhood. This review focuses on strategies to reduce the vertical transmission of HBV and HCV. The at-birth prophylaxis of newborns of HBV-infected mothers with specific immunoglobulin and vaccine plus administration of antivirals (tenofovir or telbivudine) in the third trimester of pregnancy (in case of high maternal viral load) greatly reduces the risk of transmission. In contrast, currently there is no drug able to reduce the vertical transmission of HCV infection. We discuss the possibility of reducing mother-to-child HCV transmission using newly available antivirals or antivirals in the pipeline for the treatment of hepatitis C.     

Incidence of hepatitis C virus RNA in anti-HCV negative plasma pools in Croatia.

The risks of transmitting viral infection by blood and products derived from plasma have long been known and still remain an area of concern. Blood banks and transfusion centres are faced with the imminent introduction of nucleic acid amplification testing (NAT) of plasma pools as used by the plasma industry. In this paper, we show a part of our results of a validation study of an in-house method for routine polymerase chain reaction (PCR) screening for hepatitis C virus (HCV) RNA in plasma pools and the results of testing 2,718 anti-HCV negative plasma pools for the presence of HCV RNA. The European Committee for Proprietary Medical Products (CPMP) recommended that from 1 July 1999, only batches derived from plasma pools tested and found non-reactive for HCV RNA, using validated test methods of suitable sensitivity and specificity, should be batch released by authorities. The quality and efficiency of NAT detection of HCV RNA is among others influenced by the efficacy of RNA isolation, the primer selection and the use of control samples. Using modern molecular biology techniques (sensitive and specific in-house amplification methods for detection of HCV RNA and automated sequencing), we analysed samples of plasma pools from different Croatian transfusion centres. By detection of HCV RNA in an NIBSC working reagent (genotype 3) and a Pelispy HCV RNA run control (genotype 1) we determined a high reproducibility and sensitivity (below 100 International Units (IU)/ml) for our in-house method. By direct sequencing PCR cDNAs we proved the specificity of the test system and the possibility of determining the HCV genotype when the method was used for PCR screening of HCV RNA in single donations. Of 2,718 anti-HCV negative plasma pools we have found that 2.1$ were HCV RNA positive. Results of our investigation confirm the necessity of testing HCV RNA in plasma pools to further increase the safety of human plasma-derived drugs.     

Inactivation and partition of human T-cell lymphotrophic virus, type III, during ethanol fractionation of plasma

Because of concern about the safety of immune globulins prepared for injection, we studied the effects of ethanol fractionation of human plasma on human lymphotropic virus, type III, (HTLV-III) by spiking the products of various fractionation steps with HTLV-III. Tests of inactivation and removal indicated that the ratio of residual live virus in plasma fractions/live virus in starting plasma was about 1 × 10(-15) for precipitate II from which immune globulin for injection is manufactured. The results are reassuring regarding the potential safety of immune globulin.     

丙型肝炎病毒核心抗原检测在丙型肝炎筛检中的应用

目的探讨丙型肝炎病毒核心抗原(HCV-cAg)对丙型肝炎(简称丙肝)筛查的意义。方法收集2014年10月至2015年10月8 000例门诊及住院患者,用酶联免疫吸附试验(ELISA)检测HCV-cAg、丙型肝炎病毒抗体(HCV-Ab),并对HCVcAg或HCV-Ab阳性标本采用聚合酶链反应(PCR)法检测HCV-RNA进行确诊。结果以HCV-cAg或HCV-Ab阳性为标准,从8 000例血清样本中初步筛查出阳性样本82例,经HCV-RNA确证,其中HCV-RNA阳性73例,阴性9例,HCV-cAg的灵敏度及特异度分别为45.83%和99.98%,HCV-Ab的灵敏度及特异度分别为94.44%和99.90%,联合检测HCV-cAg与HCV-Ab的灵敏度及特异度分别为100.00%和99.86%。结论在丙肝筛检工作中,HCV-cAg与HCV-Ab二者有互补性,联合检测HCV-cAg与HCV-Ab有助于提高HCV筛查率。     

Mechanisms of hepatitis C virus infection

Hepatitis C virus (HCV) is the major causative agent of chronic non-A, non-B hepatitis. The life cycle of HCV is largely unknown because a reliable culture system has not yet been established. HCV presumably binds to specific receptor(s) and enters cells through endocytosis, as do other members of Flaviviridae. The viral genome is translated into a precursor polyprotein after uncoating, and viral RNA is synthesized by a virus-encoded polymerase complex. Progeny viral particles are released into the luminal side of the endoplasmic reticulum and secreted from the cell after passage through the Golgi apparatus. Understanding the mechanisms of HCV infection is essential to the development of effective new therapies for chronic HCV infection. Several host membrane proteins have been identified as receptor candidates for HCV. Recent advances using pseudotype virus systems have provided information surrounding the initial steps of HCV infection. An HCV RNA replicon system has been useful for elucidating the replication mechanism of HCV. In this review, we summarize our current understanding of the mechanisms of HCV infection and discuss potential antiviral strategies against HCV infection.     

New antivirals against hepatitis C virus

Recently, first direct acting antiviral (DAA) against hepatitis C virus (HCV) has just approved in Japan. It is a first generation protease inhibitor, telaprevir. Telaprevir inhibits HCV NS3 & 4A serine protease, and combination with pegylated-interferon and ribavirin has now become a standard of care (SOC) for patients with genotype 1 high viral load hepatitis C. Fortunately, more than 50 new antivirals against HCV are under development including antivirals in preclinical trials. New antivirals are classified into several categories; (1) NS3 & 4A protease inhibitor, (2) NS5B polymerase inhibitor, (3) NS5A inhibitor, (4) host factor targeting antivirals, (5) interferon-related antivirals, and others. Combination of different classes of antivirals without interferon is expected to become a future SOC for hepatitis C.     

Determinants of viral clearance and persistence during acute hepatitis C virus infection.

The virological and immunological features of hepatitis C virus (HCV) infection were studied weekly for 6 months after accidental needlestick exposure in five health care workers, four of whom developed acute hepatitis that progressed to chronicity while one subject cleared the virus. In all subjects, viremia was first detectable within 1-2 weeks of inoculation, 1 month or more before the appearance of virus-specific T cells. The subject who cleared the virus experienced a prolonged episode of acute hepatitis that coincided with a CD38+ IFN-gamma- CD8+ T cell response to HCV and a small reduction in viremia. Subsequently, a strong CD4+ T cell response emerged and the CD8+ T cells became CD38- and started producing IFN-gamma in response to HCV, coinciding with a rapid 100,000-fold decrease in viremia that occurred without a corresponding surge of disease activity. Chronic infection developed in two subjects who failed to produce a significant T cell response and in two other subjects who initially mounted strong CD4+ T cell responses that ultimately waned. In all subjects, viremia was higher at the peak of acute hepatitis than it was when the disease began, and the disease improved during the viremia. These results provide the first insight into the host-virus relationship in humans during the incubation phase of acute HCV infection, and they provide the only insight to date into the virological and immunological characteristics of clinically asymptomatic acute HCV infection, the commonest manifestation of this disease. In addition, the results suggest that the vigor and quality of the antiviral T cell response determines the outcome of acute HCV infection, that the ability of HCV to outpace the T cell response may contribute to its tendency to persist; that the onset of hepatitis coincides with the onset of the CD8+ T cell response, that disease pathogenesis and viral clearance are mediated by different CD8+ T cell populations that control HCV by both cytolytic and noncytolytic mechanisms, and that there are different pathways to viral persistence in asymptomatic and symptomatic acute HCV infection.