Analytical performance of the VERIS MDx system HCV assay for detecting and quantifying HCV RNA

BackgroundThe diagnosis of HCV relies on the detection of viral RNA.ObjectiveTo evaluate the performance of the VERIS/MDx System HCV Assay, a new automated system for quantifying HCV RNA, and to compare with the COBAS^® Ampliprep/COBAS^® Taqman™ (CAPCTM) HCV Test version 2.0.Study designThe limit of detection was determined by Probit analysis with the 3rd International WHO HCV standard and precision by assaying in duplicate control samples with HCV RNA concentrations of 7.9; 5.0; 3.4; 1.6 and 0 log IU/ml over 20 days. Analytical specificity was assessed by assaying 180 samples from negative anti-HCV and HCV RNA blood donors and linearity with replicates of serial dilutions of a clinical plasma (6.4–0.6 log IU/ml). We compared the VERIS MDx HCV and CAPCTM HCV assays by testing 209 samples.ResultsThe limit of detection was 6.1 IU/ml [CI 95%: 5.0–8.3] and the precision, given by the standard deviation, was ≤0.11 log IU/ml. Specificity was 100%. The linearity ranged from 1.5 to 6.4 log IU/ml. Passing-Bablok regression analysis gave: VERIS log IU/ml = −0.33 + [1.04× CAPCTM] log IU/ml, with biases for the 25th, 50th, 75th percentiles of 0.18, −0.10 and −0.06 log IU/ml. The two assays were well correlated (ρ = 0.92, p < 0.001) and Bland-Altman analysis gave biases of 0.12, log IU/ml for genotype 1, −0.19 for genotype 2, −0.26 for genotype 3, and −0.77 for genotype 4.ConclusionThe VERIS MDx HCV assay performed well. But, we observed an under-quantification of the genotype 4 samples.     

Comparison of HCV core antigen and anti-HCV with HCV RNA results

Background

The measurement of anti-HCV antibodies using immunological methods and the confirmation of viral nuclear acid based on molecular methods is important in diagnosis and follow-up of the HCV infection.

Objectives

In this study, we aimed to analyse HCV core Antigen positivity among anti-HCV antibody positive sera to determine the significance of testing of HCV core Ag for the laboratory diagnosis of HCV infection, by considering the correlation between serum HCV core Ag and HCV RNA levels.

Methods

115 patients suspected of having hepatitis C and who were positive for anti-HCV antibody were investigated using chemiluminescent and molecular methods. Anti-HCV antibody, HCV core Ag and HCV RNA levels were detected by the Vitros ECiQ immunodiagnostic system, Architect i2000 system and RT-PCR, respectively.

Results

The sensitivity, specificity, positive and negative predictive values and accuracy rate of HCV core Antigen assay were detected as 86.5%(83/96), 100%(19/19), 100%(83/83), 59.4%(19/32), 88.7%(102/115) respectively.

Conclusion

HCV core Ag assay could be used for diagnosis of HCV infection as it is easy to perform, cost-effective, has high specificity and positive predictive value. However, it should be kept in mind that it may have lack of sensitivity and negative predictive value.     

对两种第三代丙肝试剂检测的不同功能区抗体组份研究

目的　比较第二代和第三代丙肝试剂对丙肝不同功能区抗体的检出能力。方法　用两种第二代抗 Ｈ Ｃ Ｖ Ｅ Ｉ Ａ 试剂（ Ｋ２ 中国制造, Ａ２ 美国制造） 及两种第三代主流试剂（ Ａ３ 德国制造, Ｏ３ 美国制造） 对１２１ 份来源于全国各地的供血员血样进行了检测。结果　该１２１ 份样品经 Ｒ Ｉ Ｂ Ａ Ｈ Ｃ Ｖ３ ．０ 试剂及 Ｐ Ｃ Ｒ 方法确证, 其中４３ 份为阳性样品,７８ 份为阴性样品。两种第二代试剂 Ｋ２ , Ａ２阳性检出符合率为３６／４３ 和３７／４３ , 两种第三代试剂 Ａ３ , Ｏ３ 阳性检出符合率分别为４０／４３ 和３９／４３ 。在４３ 份阳性样品中,２０ 份既含有抗 Ｈ Ｃ Ｖ 核心抗体, 也含有抗 Ｈ Ｃ Ｖ Ｎ Ｓ３ 抗体,用 Ｋ２ , Ａ２ , Ａ３ , Ｏ３ 四种试剂分别检出１８ 、１８ 、１９ 和２０ 份。１４ 份含有抗 Ｈ Ｃ Ｖ Ｎ Ｓ３ 抗体而不含有抗 Ｈ Ｃ Ｖ 核心抗体的样品中,用两种第二代试剂（ Ｋ２ , Ａ２） 分别检出９ 份和１０ 份, 而用两种第三代试剂（ Ａ３ , Ｏ３） 则全部检出。与此相反,９ 份含有抗 Ｈ Ｃ Ｖ 核心抗体而不含抗 Ｈ Ｃ Ｖ Ｎ Ｓ３ 抗体的样品, 用两种第二代试剂（ Ｋ２ , Ａ２）均可检出, 而用两种第三代试剂（ Ａ３ , Ｏ３） 却     

Total HCV core antigen assay. A new marker of HCV viremia and its application during treatment of chronic hepatitis C

The present study assesses the clinical usefulness of the hepatitis C core antigen assay for monitoring of patients being treated for chronic hepatitis C virus (HCV) infection. Eighty-six serum samples were selected at random from 16 patients and levels of HCV RNA and HCV core antigen were determined simultaneously and in parallel to compare both techniques. The data obtained were compared by Pearson’s correlation and the coefficients calculated by Fisher transformation and by calculating the difference and standard error. A good linear correlation was observed between both techniques. Maximum correlation, with significant difference, was found between patients infected with the 1a genotype and other genotypes. In conclusion, the HCV core antigen assay is useful for the diagnosis of early infection; however, its use for determining the exact timing of viral elimination during treatment is clearly unsuitable.     

Clinical significance of hepatitis C viral RNA status and its correlation to antibodies to structural HCV antigens in anti-HCV reactive patients with normal liver tests

Extensive serological testing and HCV RNA determination by RT-PCR was performed in serum, PBMCs, and liver tissue in thirteen anti-HCV reactive patients with persistently normal liver tests. Absolute concordance in the status of HCV RNA between serum, PBMCs, and liver was noted. Five patients were HCV RNA positive but only three had mild histological changes. Eight patients were HCV RNA negative in all three sites and had virtually normal liver histology. Patterns of reactivity in RIBA™ 2.0 strip immunoblot assay did not differentiate viremic from nonviremic patients. ELISA testing using multiple individual HCV recombinant antigens from the structural and non-structural regions of HCV demonstrated mean antibody titers to the structural antigens, in particular HCV E2 antibodies, to be significantly lower in HCV RNA negative patients. The status of HCV RNA in the serum appears to infer the status of HCV RNA in the liver and PBMCs in patients with persistently normal liver tests. Patients with persistently normal liver tests and undetectable HCV RNA have probably spontaneously cleared HCV infection. © 1996 Wiley-Liss, Inc.     

抗-HCV和HCV-RNA检测及其与ALT的相关性分析

目的探讨化学免疫发光法（CLIA）定量检测抗-HCV和FQ-PCR法检测HCV-RNA含量与丙氨酸氨基转移酶（ALT）水平的相关性。方法用CLIA定量筛选抗-HCV阳性的100例病人标本,以荧光定量PCR法检测HCV-RNA含量和酶速率法检测ALT浓度水平,并对所得数据进行统计分析。结果在100份抗-HCV阳性标本中,检出HCV-RNA阳性者76例,阳性率为76%。随着抗-HCV的S/CO值增高,HCV-RNA检出率增高较明显;ALT水平与HCV-RNA含量无显著相关性（P〉0.05）,但ALT异常率与HCV-RNA含量呈正相关。结论在HCV诊断与疗效观察中,血清抗HCV、HCV-RNA和ALT指标各有利弊,3者有机结合能正确诊断和预测肝脏损伤及评价疗效。     

Evaluation of Xpert HIV-1 Qual assay for resolution of HIV-1 infection in samples with negative or indeterminate Geenius HIV-1/2 results

BackgroundDiagnosis of HIV infection is a multistage algorithm. Following screening with 4^th generation combination immunoassay, confirmation of HIV infection is performed with an antibody assay that differentiates HIV-1 from HIV-2 infection. In the newly updated algorithm, samples that are nonreactive or indeterminate in the differentiation assay are to be tested with an HIV-1 nucleic acid amplification (NAAT) test for resolution. Xpert HIV-1 Qual is a new NAAT assay approved for the identification of HIV infection in whole and dried blood.ObjectivesTo assess the performance of Xpert HIV-1 Qual supplementary assay in resolving the clinical status of serum samples reactive by 4^th generation immunoassays and indeterminate or negative by Geenius HIV-1/2 confirmatory assay.Study designIn a retrospective study, samples from 97 individuals for whom the true HIV-1 status was already known (by follow-up samples) and which were negative or indeterminate by HIV-1/2 Geenius assay were tested with Xpert Qual HIV-1 assay.ResultsXpert Qual assay correctly classified all 97 samples from HIV-1 positive (n = 49) and negative (n = 48) individuals. The sensitivity and specificity of Xpert Qual when using the true HIV status as a reference were 100% (92.7–100% at 95% confidence interval [CI] and 92.6–100% at 95% CI, respectively).ConclusionsApplying Xpert Qual HIV-1 assay in the new HIV multi-stage diagnostic algorithm correctly classified 100% of HIV-1 infections including 49 from HIV-1 carriers who have not yet seroconverted. With this assay the total time required for acute HIV diagnosis could be significantly reduced.     

Hepatitis E virus seroprevalence in acute viral hepatitis in a developed country confirmed by a supplemental assay

Hepatitis E virus (HEV) infection is prevalent among cases of acute viral hepatitis in young adults in developing countries. HEV infection is not restricted to endemic areas, but would appear to be worldwide in distribution. In order to document the incidence of HEV infection in acute hepatitis cases in a developed country, IgG and IgM anti-HEV antibodies and HEV RNA were tested in 101 Caucasian patients with acute viral hepatitis; 92 of these cases had markers of acute viral hepatitis other than HEV. Forty-seven (46.5%) cases had IgG anti-HEV; IgM anti-HEV and HEV viremia were not detected. As the incidence of anti-HEV was higher than would be expected, the possibility of the occurrence of false positive results was subsequently investigated. Supplemental antibody testing, using a broadly reactive epitope region, reduced the frequency of anti-HEV to 17%. Therefore, supplemental antibody testing confirms the hepatitis E virus seroprevalence in a developed country. Since IgM anti-HEV and HEV viremia were not detected, persons with IgG anti-HEV may be “subclinical HEV cases,” or have long-lived antibodies in their circulation. © 1996 Wiley-Liss, Inc.     

False-positive reactivity of anti-human leukocyte antigen antibodies detected using the single-antigen bead assay

The single-antigen bead assay (SABA) demonstrates high sensitivity and specificity for detecting anti-human leukocyte antigen (HLA) antibodies. However, SABA may produce false-positive results for anti-HLA antibodies. Herein, we analyzed the data of patients with complement-dependent cytotoxic crossmatch^?/flow cytometric crossmatch^?/SABA^+/? results to determine false-positive results for anti-HLA antibodies. We also determined the prevalence of false-positive results by comparing false-positive data from our laboratory and national allele frequency data obtained with high-resolution HLA typing. For HLA-A, -B, -C, and -DR, a ratio of positive frequency to allele frequency of ≥3 in our laboratory was considered a false-positive result. For HLA-DQA1/DQB1 and HLA-DPA1/DPB1, we considered the positive frequency of ≥3 as a false positive result due to lack of haplotype frequency data. SABA results from 284 patients (78.0%) demonstrated false reactivity. The antibody against HLA-C*17:01 displayed the highest frequency ratio (298.3). If false-positive reactivity is suspected, results should be confirmed using different methods. If confirmation tests are unfeasible, comparing the allele frequency with the positive rate of detected anti-HLA antibodies and using a ratio ≥3 may facilitate the interpretation of SABA results. The positive rate of anti-HLA antibodies can be validated using the HLA allele frequency of the population to determine false-positive results.     

HCV replication in mononuclear cells stimulates anti-HCV-secreting B cells and reflects nonresponsiveness to interferon-α

Recently, it was demonstrated in chronic hepatitis C that the release of IgG and IgM anti-HCV antibodies by mononuclear cells (PBMCs) correlated with inflammatory activity, HCV persistence in serum, and negative outcome from antiviral therapy. Thus, persistent antigenic stimulation of the antibody-secreting B cells has been suggested. In this study, PBMCs were derived from 13 patients with chronic hepatitis C. Nucleic acids were extracted by the guanidine-thiocy-anate-method, and plus- and minus-stranded HCV-RNAs were determined using primers from the 5′-untranslated region of HCV. Simultaneously, unstimulated PBMCs were cultured for 8 days and anti-HCV antibodies were detected in the supernatants by EIA and RIBA. Seven patients (53.8%) had both plus- and minus-stranded HCV-RNA in PBMCs, while anti-HCV antibodies were secreted in vitro. One of 2 patients with plus- but not minus-stranded HCV- RNA in PBMCs was anti-HCV positive in vitro, whereas 4 patients without HCV-infected PBMCs were anti-HCV negative in vitro. Eight patients received antiviral therapy with interferon-α2b. Four nonresponders and 1 partial responder had plus- and minus-stranded HCV- RNA in PBMCs and anti-HCV secretion in vitro. On the other hand, 2 complete responders and another partial responder showed neither HCV infection of PBMCs nor anti-HCV secretion in vitro. In conclusion, infection of PBMCs by HCV is observed frequently in patients with chronic hepatitis C, and may be related to the high rate of nonresponders to antiviral treatment. The close correlation of anti-HCV secretion in vitro and viral replication suggests that the humoral response to HCV is triggered by viral antigens that are expressed on infected mononuclear cells. © 1995 Wiley-Liss, Inc.     

Effect of genotypes on the quantification of hepatitis C virus (HCV) RNA in clinical samples using the amplicor HCV monitor test and the quantiplex HCV RNA 2.0 assay (bDNA)

The Amplicor HCV Monitor test and the Quantiplex HCV RNA 2.0 (bDNA) assay are two commercially available assays for the quantification of hepatitis C virus (HCV) RNA in clinical samples. A direct comparison of the two assays was carried out using sera frozen previously from patients known to be chronically infected with HCV. Overall, 61 samples from 51 patients were tested simultaneously by the two methods: 67% (28/42) of the patients were infected by HCV genotype/serotype 1, 10 % (4/42) with type 2, and 24% (10/42) with type 3. When the absolute value from each assay was examined, the Quantiplex assay gave a consistently higher reading and the mean logarithmic difference between the two assays was 1.4 (1.0 in type 1, 2.0 in type 2, and 2.2 in type 3). When analyzed according to genotype, strong correlation was observed between the two assays for type 1 (r = 0.83, 95% CI 0.63–0.93, P < 0.01), but not for nontype 1 samples. Despite the difference in absolute level reported by the two assays, there was a consistent trend of change in HCV RNA concentration by both assays in patients whose consecutive samples were analyzed and the differences between the two assays in consecutive samples were within 0.4 log of each other. The results suggested that with samples containing genotype 1, the Amplicor assay was more sensitive than the Quantiplex assay by about one log. However, the sensitivities of the two assays with nontype 1 samples were much closer probably due to the failure of the Amplicor assay to quantify nontype 1 genotypes effectively. J. Med. Virol. 55:191–196, 1998. © 1998 Wiley-Liss, Inc.     

Evaluation of a modified commercial assay in detecting antibody to hepatitis C virus in oral fluids and dried blood spots

Oral fluid testing is an effective alternative to serum antibody testing for surveillance of human immunodeficiency virus (HIV) and hepatitis B infections, and is being extended to hepatitis C infections. The objective of this study was to determine and compare the sensitivity and specificity of a modified commercial assay for the detection of antibody to hepatitis C virus (anti-HCV) in oral fluids collected by two different oral fluid collection devices (the Epitope OraSure trade mark and Sarstedt Salivette ) and in dried fingerprick blood spots. In this study, 253 anti-HCV seropositive patients and 394 blood donors (all anti-HCV negative) were recruited between August 2000 and January 2001. Each participant provided oral fluid specimens by OraSure and Salivette, and at least one dried blood spot. Serum specimens were collected from the patients whenever possible. For those injecting drug users who did not provide a serum specimen, HCV status was established on the basis of previous testing. All the nonserum samples were tested for the presence of anti-HCV, using a modified Ortho HCV 3.0 SAVe enzyme-linked immunosorbent assay (ELISA) protocol. The recommended preliminary cutoffs for the modified ELISA were suboptimal. Further, the sensitivity, specificity, and positive and negative predictive values could be improved by varying the cutoff and taking into account the likely prevalence of HCV in the population under investigation. For instance, given a population with a 50% prevalence of anti-HCV, the optimal sensitivities of the modified assay on OraSure, Salivette, and dried blood spots were 92%, 83%, and virtually 100%, respectively, in contrast to 83%, 59%, and 99% using the preliminary cutoffs. The respective optimal specificities were 99%, 93%, and 100%. In conclusion, oral fluids collected by the OraSure device provide an extremely useful method to conduct public health surveillance of not only HIV, but also hepatitis C, among injecting drug users. In addition, dried blood spot specimens may be useful for surveillance and could be employed as a first line diagnostic specimen.     

Performance evaluation of the Artus hepatitis C virus QS-RGQ assay

Accurate determination of hepatitis C virus RNA level is essential for evaluating the response to antiviral therapy, to determine the duration of treatment, and to predict treatment outcome. Currently, two real-time based polymerase chain reaction assays are used widely to monitor the hepatitis C RNA level: the Abbott RealTime HCV assay and the Cobas Taqman HCV assay. Recently, a third assay has become commercially available: the Artus HCV QS-RGQ assay, which uses the QIAsymphony SP/AS platform for sample preparation and PCR-setup, and the Rotor-Gene Q for amplification and detection. In this study, the performance of the Artus HCV QS-RGQ assay was tested on 105 plasma samples and compared to that of the Cobas Taqman HCV assay. Linear regression analysis showed a good agreement between the two assays. A slightly better sensitivity was observed with the Cobas Taqman assay, while higher hepatitis C viral RNA levels were measured by the Artus HCV QS-RGQ assay in samples positive for hepatitis C genotypes 4. Taken together, the data suggest that the Artus HCV QS-RGQ assay is useful in a diagnostic setting. The combination with the versatile QIAsymphony SP/AS system may represent a major advantage for clinical virological laboratories aiming at optimizing their workflow.     

Serotyping and genotyping of hepatitis C virus (HCV) strains in chronic HCV infection

Hepatitis C virus (HCV) genotypes can be established by methods based on PCR typing and serological typing. The accuracy of these methods depends on their sensitivity and specificity. These should be compared with the reference method, direct sequencing, and analysis of viral genomes. Among the serologic methods recently developed, the performance of a new serotyping assay (RIBA HCV 3.0 SIA, Chiron corporation, Emeryville) was assessed using a panel of 147 well-characterized French isolates from chronic hepatitis C patients. Definitive genotypes of the isolates were established by direct sequencing in 5′ NC and in some cases in NS-5B. HCV serotypes 1, 2, and 3 were determined by measuring type specific antibodies to core and NS-4 derived peptide antigens. Of the 147 sera, serotypic-specific antibodies were detected in 136 (sensitivity, 92.5%). The specificity of the RIBA SIA HCV serotyping assay was 92.6% (including samples with mixed results); without these, the specificity was 80.1%. Analysis of the 28 discrepant samples showed that (1) a different serotype was found in 18 samples including five for genotype 1, three for genotype 2, two for genotype 3, five for genotype 4, and three for genotype 5, and that (2) ten patients showed a reactivity with mixed serotypes, one had circulating antibodies to type 1 or 2, and nine had circulating antibodies to type 1 or 3. In summary, except for genotypes 4 and 5, the results of the test were well correlated (85.7%) with those of direct sequence genotyping. The former test is rapid and does not require the strict HCV RNA storage and preservation conditions of the latter. This new method may thus be considered as an alternative for HCV typing. However, although it is convenient, its lower sensitivity compared to the molecular typing method and the discrepant results limit its routine use in a clinical context. J. Med. Virol. 52:391–395, 1997. © 1997 Wiley-Liss, Inc.     

用ELISA方法检测埃可病毒感染的特异性IgM抗体

目的 研究埃可病毒感染的无菌性脑膜炎的诊断方法。方法 采用埃可病毒混合抗原包被酶标板，用抗人γ链处理人脑脊液标本，通过酶标二抗及底物显色，建立了抗埃可病毒IgM的间接ELISA检测方法；并用特异性试验、对照和重复性试验证实方法的可靠性和实用性。结果 在临床诊断为无菌性脑膜炎的78例患者脑脊液中有14例阳性（17.9%)，而细菌性脑膜炎的36例患者脑脊液中仅有1例阳性（2.8%)，28例脑外伤患者脑脊液均为阴性，ELISA阳性的5份脑脊液中和试验4例阳性，而ELISA阴性的5份脑脊液中和试验均为阴性；该方法与脊髓灰质炎病毒、柯萨奇A组病毒7型和柯萨奇B组病毒1-6型无交叉反应；ELISA阳性的6份标本经特异性IgM破坏和阻断试验均全部转为阴性。结论 本方法快速，简便、可靠、适合于临床早期特异性诊断。     

Loss of serum HCV RNA at week 4 of interferon-α therapy is associated with more favorable long-term response in patients with chronic hepatitis C

To determine the virological factors associated with a favorable long-term response to interferon-α (IFN) therapy in chronic hepatitis C virus (HCV) infection, 61 Japanese patients with chronic HCV infection were treated with IFN for 24 weeks (780 million units in total) and followed for 8 to 16 months after cessation of therapy. Ten patients dropped out because of severe side effects. Of the 51 patients who completed IFN therapy, 23 showed complete and sustained response (CR→SR), 13 complete response with early relapse (CR→Rel), and 15 no response to IFN (NR). For the pretreatment serum HCV RNA level, 20/23 who had CR→SR had <l0⁶ eq/ml compared to 3/13 CR→Rel and 1/15 NR (P< 0.01). Serologically defined HCV type 2 infection was also associated with a better opportunity to develop CR→SR compared to CR→Rel of NR (P<0.01). Loss of serum HCV RNA at week 4 of IFN therapy was also associated with a more favorable long-term response [17/19 CR→SR were HCV RNA negative compared to 3/11 CR→Rel (P<0.01)and2/13NR(P<0.01)]. n contrast, normalization of serum alanine ami-notransferase (ALT) levels at week 4 was found in 9/19 CR→SR compared to 8/11 CR→Re1 (P= NS), and 0/13 in NR (P<0.01). Six months after cessation of IFN therapy, 3/25 CR→SR patients were HCV RNA positive despite normalization of serum ALT levels. These data indicated that in addition to pretreatment serum HCV RNA levels and HCV type, the kinetics of response to IFN (at week 4) were also predictive of subsequent long-term response to IFN in patients with chronic HCV infection. © 1995 Wiley-Liss, Inc. © 1995 Wiley-Liss, Inc.     

Clinical evaluation of the COBAS Ampliprep/COBAS TaqMan for HCV RNA quantitation in comparison with the branched-DNA assay

Diagnosis and monitoring of HCV infection relies on sensitive and accurate HCV RNA detection and quantitation. The performance of the COBAS AmpliPrep/COBAS TaqMan 48 (CAP/CTM) (Roche, Branchburg, NJ), a fully automated, real-time PCR HCV RNA quantitative test was assessed and compared with the branched-DNA (bDNA) assay. Clinical evaluation on 576 specimens obtained from patients with chronic hepatitis C showed a good correlation (r = 0.893) between the two test, but the CAP/CTM scored higher HCV RNA titers than the bDNA across all viral genotypes. The mean bDNA versus CAP/CTM log10 IU/ml differences were -0.49, -0.4, -0.54, -0.26 for genotype 1a, 1b, 2a/2c, 3a, and 4, respectively. These differences reached statistical significance for genotypes 1b, 2a/c, and 3a. The ability of the CAP/CTM to monitor patients undergoing antiviral therapy and correctly identify the weeks 4 and 12 rapid and early virological responses was confirmed. The broader dynamic range of the CAP/CTM compared with the bDNA allowed for a better definition of viral kinetics. In conclusion, the CAP/CTM appears as a reliable and user-friendly assay to monitor HCV viremia during treatment of patients with chronic hepatitis. Its high sensitivity and wide dynamic range may help a better definition of viral load changes during antiviral therapy.     

抗肠道病毒EV71型外壳蛋白VP1单克隆抗体的制备和鉴定

目的 制备具有中和活性的抗肠道病毒EV71型外壳蛋白VP1的单克隆抗体.方法 人工合成SP55和SP70(分别包含VP1的第163-177,208-222位氨基酸)两段VP1的多肽,分别免疫BALB/c小鼠,常规杂交瘤技术进行细胞融合,用间接酶联免疫吸附试验(ELISA)筛选阳性杂交瘤细胞并测定效价.用分泌的单抗和EV71病毒在RD细胞上进行中和试验以检验其中和活性.结果 得到2株能稳定分泌抗肠道病毒EV71型VP1蛋白单克隆抗体的杂交瘤细胞株,2株单抗的中和效价分别为1:8和1:16.结论 成功制备出2株具有中和活性的抗肠道病毒EV71型VP1蛋白单克隆抗体,为其下一步应用打下基础.     

Total HCV core antigen assay: a new marker of hepatitis C viremia for monitoring the progress of therapy

The ability of the total hepatitis C virus (HCV) core antigen assay was evaluated for monitoring the therapeutic responses of HCV-infected patients treated with interferon. The ability to detect and quantitate an independent structural protein component of HCV, in the presence of circulating antibodies, makes this assay a valuable new tool in diagnosis and treatment monitoring. Measurement of total core antigen showed a strong dynamic correlation with HCV RNA data and may serve as an alternative direct marker of viral infection. In addition, with the advent of additional treatment protocols, a rapid, reliable assay for changes in HCV load may permit more frequent patient assessment and tailoring of the therapeutic regimen.