Evaluation of the use of a combined HCV antigen/antibody assay in routine laboratory practice

BACKGROUND

Combined hepatitis C virus (HCV) antigen/antibody (Ag/Ab) assays offer the advantage of a shorter window phase compared to traditional anti-HCV antibody assays. These assays have been extensively evaluated for the screening of healthy blood donors, but not in routine laboratory practice.

METHODS

We evaluated the performance of the combined HCV Ag/Ab assay Monolisa Ultra and compared it to Monolisa anti-HCV Plus (which only detects anti-HCV antibodies) in 61 HCV RNA-positive patients (genotypes 1 to 5) and in 276 consecutive AxSYM HCV-reactive patients. Discordant sera were tested with immunoblot and PCR.

RESULTS

All 61 PCR-positive sera were positive with AxSYM, Monolisa Ultra, and Monolisa Plus. Of the 276 consecutive AxSYM-reactive patients, 177 were confirmed as HCV-positive, 78 were HCV-negative and 21 were HCV-indeterminate. There were 4 false-positive results with Monolisa Ultra compared to 1 false-positive result with Monolisa PLus. The signal/cut-off ratio in immunoblot-negative sera was significantly higher with HCV Ultra compared to HCV Plus (p < 0.01). Sensitivity and specificity in AxSYM-reactive sera were 99.4% and 94.9% for Monolisa Ultra and 99.4% and 98.7% for Monolisa Plus.

CONCLUSION

When used as a secondary test, the sensitivity of the combined HCV Ag/Ab assay Monolisa Ultra was excellent, but specificity was reduced in AxSYM-reactive sera compared to Monolisa Plus.

[Atomic force microscopy detection of serological markers of viral hepatites B and C]

The aim of the study was to demonstrate the possibility of detection of serological markers, containing the hepatitis B surface antigen (HBsAg) and hepatitis C virus core-antigen (HCVcoreAg) in human serum, by use of a new atomic force microscopy (AFM)-based nanotechnological approach. In this study, the immobilization on AFM-chip of antibodies against the hepatitis B virus surface antigen (anti-HBsAg) as well as the antibodies against the hepatitis C virus core antigen (anti-HCVcoreAg) was performed. It was shown that such approach enables to detect: HBsAg, HCVcoreAg and the viral fragments containing these antigens in the serum. Comparative analysis of detection of HBsAg- and HCVcoreAg-containing particles by use of the AFM method vs. traditional methods (ELISA, PCR) has demonstrated the 75% coincidence of results between the AFM and the latter two methods.

[Detection of hepatitis C virus antigen in hemodialysis patients]

OBJECTIVE

To investigate the utility of the HCV core antigen ELISA in the detection of HCV infection in hemodialysis patients and to compare with Anti-HCV antibodies 3rd generation ELISA.

METHODS

Two hundred fifty hemodialysis patients were included in the study. Anti-HCV antibodies and total HCVcAg was determined by ELISA kits. HCV RNA was determined using reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Forty-three out of 250 (17.2%) patients were positive for anti-HCV antibodies and 18% were positive for HCVcAg. 13/250 (5.2%) were positive for HCVcAg but anti-HCV negative, All 13 were confirmed viremic by in-house nested RT-PCR leading to specificity of 100%. Viral load of (49258 +/- 28682) copies/ml were detected in HCVcAg positive cases was higher in comparison to (23938 +/- 10780) copies/ml in the anti-HCV positive group (P < 0.05). The viral load of 4 negative cases for HCVcAg assay but anti-HCV positive was 306 +/- 161 copies/ml which was significantly lower in comparison to HCVcAg positive group (P < 0.001).

CONCLUSION

Detection of total HCVcAg together with anti-HCV will be useful for patients undergoing hemodialysis who have a longer window period due to immunosuppressed state. HCVcAg was compatible for the HCV RNA in serum and total HCVcAg ELISA is both a cost-effective and a less labor-intensive alternative to PCR, enhancing its clinical utility.

Simultaneous detection of anti-HCV antibody and HCV core antigen

HCV infection is usually diagnosed by means of an enzyme immune assay for the detection of antibody against HCV. The window period between infection and seroconversion remains a dramatic problem in the transfusional and diagnostic setting. In this chapter, we report (i) procedures for assays using two different approaches designed to reduce the window period and (ii) performance in terms of specificity and sensitivity in the detection of both antibody and antigen, and we compare their efficacy with that of commercial assays.

[Rationale for the implementation of pre-operative testing for HCV in the light of anti-HCV and HBsAG tests results in surgical patients from a teaching hospital]

Many Polish hospitals compel patients admitted for elective surgery to be immunised for HBV; testing for HBsAg is recommended before. We surveyed immunisation coverage for HBV and prevalence of HBsAg and anti-HCV among surgical patients to assess existing pre-operative screening policies.

METHODS

questionnaire data and sera were collected anonymously from 400 consecutive adults admitted to 4 surgical wards of a teaching hospital in Szczecin, Poland during October 2006/December 2007. Samples were assayed for HBsAg, and anti-HCV.

RESULTS

Serologic evidence for either HBsAg or anti-HCV was 2.3% (9/400; 95% CI: 1.2-4.2%), all in elective cases; 1.5% (6/400; 95% CI: 0.7-3.2%) were positive for anti-HCV, 0.75% (3/400; 95% CI: 0.26-2.18%) for HBsAg. None of anti-HCV positive patients was aware of their infection, as well as 1 in 3 HBsAg carriers. Anti-HCV and HBsAg prevalence in 20131 blood donors which served as controls were 0.08% (95% CI: 0.02-0.15%) and 0.11% (95% CI: 0.04-0.2%) respectively. HBV immunisation coverage was 247/398 (62%), higher (p < 0.0001) in those undergoing elective rather than emergency surgery.

CONCLUSIONS

anti-HCV prevalence was double that for HBsAg. These data give evidence for the expansion of the existing screening programme for blood borne infections among elective surgical patients, to also cover those infected with HCV. A third of patients were unimmunised, remaining a potential pool for HBsAg carriers.

Partial splenic embolization reverses insulin resistance in patients with liver cirrhosis

BACKGROUND

It is well known that patients with liver cirrhosis often develop insulin resistance and diabetes mellitus. Recently, we encountered a liver cirrhosis patient in whom partial splenic embolization (PSE) improved insulin sensitivity. Therefore, we conducted further investigation about PSE and insulin resistance.

METHODS

Thirty-seven consecutive patients with liver cirrhosis underwent PSE. Hemodynamic changes, blood counts, and homeostasis model assessment of insulin resistance (HOMA-IR) were assessed before and 2 weeks after PSE.

RESULTS

PSE resulted in decreased splenic venous flow and increased intestinal venous flow to the liver. Platelet counts before and after PSE were 7.7+/-0.5 x 10(4) /microL, 15.0+/-1.4 x 10(4) /microL, respectively (p<0.01). HOMA-IR before and after PSE were 6.5+/-2.1, 3.3+/-0.6, respectively (p<0.05). HCV core antigen before and after PSE were 6,340+/-1,296 fmol/L, 4,112+/-873 fmol/L, respectively (p<0.05). Conclusion PSE significantly reverses insulin resistance in patients with liver cirrhosis. The increase in intestinal venous flow to the liver and reduced HCV viral load were thought to be mechanisms of improvement in insulin sensitivity after PSE.

HBV genome integration and genetic instability in HBsAg-negative and anti-HCV-positive hepatocellular carcinoma in Japan

The aim of this study is to clarify the existence and the form of HCV RNA and HBV DNA genome integration and genetic instability in liver tissue with HBsAg-negative and anti-HCV-positive HCC. We investigated 16 Japanese patients with HBsAg-negative and anti-HCV-positive HCC. HBV genome integration into host cell genome by Southern hybridization and PCR was examined. Moreover, we analyzed loss of heterozygosity (LOH) and replication errors (RER) of chromosomes 2p, 3p and 17p using the PCR and an autosequencer to determine the three microsatellite regions D2S123, D3S1067, TP53. Eight (50.0%) of 16 were found to have integrated genome of HBV in tumor tissue (T) by PCR. In even the non-tumor regions (NT), seven patients (43.8%) were found to have HBV genome integration. The coincidence between T and NT was found in 4 (25%). Integration of HBV-X gene in T was revealed in three (18.7%), and HBV-integration was confirmed in all NT. No integration of the X gene alone was found in the liver tissue. Five (37.5%) of eight HBV DNA integrated cases simultaneously had HCV RNA minus strand. Concerning the genetic instability, RER were detected in two of 16 (12.5%). RER at 2p; D2S123 was observed in one of 16 (6.2%) and at 3p; D3S1067 was observed in one (6.2%). LOH at the D2S123 locus was observed in one of 12 tumors with heterozygosity (8.3%). There was no genetic instability (LOH or RER) of TP53 which was p53 locus on 17p in T. There was only one case of eight HBV DNA integrated cases (6.2%) with genetic instability of RER of 3p simultaneously in T. In conclusion, the majority of HBsAg-negative and anti-HCV-positive HCC liver tissue was found to have HCV-RNA and HBV DNA integration, and in some samples, HBV DNA integration and genetic instability were concurrently confirmed. It is speculated that multistep carcinogenesis may have been proposed for HCC oncogenetic progression.

Establishment of hybrid cell lines producing monoclonal antibodies to a synthetic peptide from the E1 region of the hepatitis C virus

We aimed at establishing hybridoma cells secreting monoclonal antibodies (mAbs) against E1 synthetic peptide of HCV. BALB/c mice were immunized with HCV E1-synthetic peptide (GHRMAWDMM) and its spleenocytes were fused with the P3NS1 myeloma cell line. Two highly reactive and specific mAbs (10C7 IgG2b mAb, and 10B2 IgG1 mAb) were generated. The target HCV E1 antigen was identified at approximately 38 kDa in serum of infected individuals. A newly developed ELISA detected the target antigen in 90% of sera from HCV RNA infected individuals with a specificity of 84%. So, the generated mAbs may provide promising probes for serodiagnosis of HCV infection.

[HCV genotypes in Polish blood donors in period 1995-2007]

The results of HCV genotype distribution between 1995 and 2007 in Polish blood donors were analyzed. Special attention was drawn into the analysis of HCV polymorphism isolated from blood donors in the early phase of infection (RNA HCV positive/anti-HCV negative). Such donors identified in Poland since 2000 when the NAT for HCV was introduced are very important for molecular epidemiology analysis. The increasing frequency of 3a and 4 genotypes is observed in comparison to blood donors and patients with anti-HCV antibodies.

[Evaluation on the use of detection of hepatitis C core antigen for screening blood donor]

OBJECTIVE

To investigate the value of detection of hepatitis C virus core antigen (HCV-cAg) for screening blood donor by using the internal reagent enzyme immunoassay (EIA) and anti-HCV antibody.

METHODS

The first and repeat assays were performed for detection of serum anti-HCV and HCV-cAg ELISA in 3972 donor's serum specimens from August to October of 2004. Twenty-five donors positive for anti-HCV were tested with HCV-cAg EIA kits and the results were compared with the results of HCV RNA determination with RT-PCR method.

RESULTS

In 3972 donor's serum samples, only 1 serum specimen was positive for HCV RNA identification among 10 specimens which were positive for anti-HCV in first assays, and only 1 serum specimens was positive for HCV RNA identification among 12 specimens positive for anti-HCV in repeat assays, only 2 serum specimens were positive HCV RNA identification in 3 specimens which were positive for HCV-cAg assays.

CONCLUSION

The sensitivity of HCV-cAg ELISA is similar to HCV RT-PCR, but it is much cheaper. Therefore, HCV-cAg ELISA and anti-HCV may be used together to screen blood donor.

[Improvement of sensitivity in the second generation HCV core antigen assay by a novel concentration method using polyethylene glycol (PEG)]

A HCV core antigen (Ag) detection assay system, Lumipulse Ortho HCV Ag has been developed and is commercially available in Japan with a lower detection level limit of 50 fmol/l, which is equivalent to 20 KIU/ml in PCR quantitative assay. HCV core Ag assay has an advantage of broader dynamic range compared with PCR assay, however the sensitivity is lower than PCR. We developed a novel HCV core Ag concentration method using polyethylene glycol (PEG), which can improve the sensitivity five times better than the original assay. The reproducibility was examined by consecutive five-time measurement of HCV patients serum, in which the results of HCV core Ag original and concentrated method were 56.8 +/- 8.1 fmol/l (mean +/- SD), CV 14.2% and 322.9 +/- 45.5 fmol/l CV 14.0%, respectively. The assay results of HCV negative samples in original HCV core Ag were all 0.1 fmol/l and the results were same even in the concentration method. The results of concentration method were 5.7 times higher than original assay, which was almost equal to theoretical rate as expected. The assay results of serially diluted samples were also as same as expected data in both original and concentration assay. We confirmed that the sensitivity of HCV core Ag concentration method had almost as same sensitivity as PCR high range assay in the competitive assay study using the serially monitored samples of five HCV patients during interferon therapy. A novel concentration method using PEG in HCV core Ag assay system seems to be useful for assessing and monitoring interferon treatment for HCV.

Feasibility and cost-benefit of implementing pooled screening for HCVAg in small blood bank settings

To examine the accuracy, feasibility and benefits of screening for hepatitis C virus core antigen (HCVAg) using enzyme-linked immunosorbent assay (ELISA) test in pools. Many countries cannot afford to test blood donations for hepatitis C using molecular methods. Screening individual units using the ELISA HCVAg test is an acceptable, yet still expensive, alternative, especially for small blood bank settings. This study evaluated the option of screening for HCVAg in pools. The sensitivity (Se) and specificity (Sp) of HCVAg in pools of three and six antibody-negative samples were estimated and compared with polymerase chain reaction (PCR). The feasibility and cost-benefit of the assay was assessed on 960 routine samples collected at a hospital blood bank in Gaza. Based on results for 50 PCR-positive pools and 50 and 110 PCR-negative pools of three and six, the Se of testing in pools of three and six samples is 80-82% [95% confidence interval (CI): 66.3-91.4] and Sp >or=98% (95% CI: 89.4-100.0) compared with PCR. The incidence of antigen in donors in Gaza was 0.1% (95% CI: 0-0.56). Cost analyses suggested significant benefits from implementing screening blood donations for HCVAg when the incidence rate is >4.2/10,000, leading to reduction in the expenditures needed to treat patients infected with HCV. The risk of transfusion-transmitted hepatitis C in resource-deprived developing countries can be efficiently reduced by additional screening of antibody-negative blood donations for HCVAg in pools of six.

[Comparative analysis of hepatitis C virus core protein in the plasma and serum samples from HCV-infected blood donors and patients with hepatitis C]

The aim of the study was to develop a sensitive and specific method for revealing the direct marker of hepatitis C virus (HCV)--core protein in the serum and to test it in the laboratory setting. Experiments were made on plasma and serum samples from asymptomatic HCV-seropositive blood donors (n=65), patients with acute (AHC) and chronic (CHC) hepatitis C (n=295), and HCV-seronegative blood donors (n=20). The processing protocol for serum included their concentration by means of polyethylene glycol and subsequent treatments of pellets to detect core protein in free virions, nonenveloped nucleocapsids, and immune complexes. This allowed an assay to be developed for the detection of core protein, by using a sandwich ELISA. Inclusion of a combination of three original monoclonal antibodies into the sandwich could reveal in the samples core proteins of at least 3 genotypes of HCV (1, 2, and 3) with a sensitivity of 20 pg/ml in the majority of HCV-infected subjects. The results of determination of core protein and HCV RNA correlated with a high degree of sensitivity. To detect HCV in the blood of patients with AHC, it was shown to be sufficient to find freely circulating virions whereas an analysis of immune complexes should be included in cases of CHC to achieve more sensitivity. The findings are a basis for developing a test system for the diagnosis of hepatitis C, including its early stages before seroconversion and for determining a viral load during interferon therapy. Introduction of the method into practice increases the reliability of the diagnosis of hepatitis C and virus-free safety of blood transfusions.

[Clinical assessment of Monolisa HCV Ag-Ab ULTRA (Bio-Rad) in a general hospital]

INTRODUCTION

To evaluate a new test based on simultaneous detection of HCV antibodies and antigen (Monolisa HCV Ag/Ab ULTRA; Bio-Rad, Marnes la Coquette, France).

METHODS

We studied samples from two groups of patients and 7 commercial HCV seroconversion panels (75 samples). Group 1: 1360 serum samples from patients referred for routine testing of anti HCV antibodies. Group 2: 333 serum samples from 183 hemodialysis patients. All samples were tested by the Ortho HCV 3.0 technique (Ortho-Clinical Diagnostics, Amersham, UK) and the Monolisa HCV Ag-Ab ULTRA technique.

RESULTS

Group 1: Seventy-four of 1360 serum samples were positive by Ortho HCV and 77 by Monolisa. In 1353 samples, the results with the two tests were concordant: 1281 negative and 72 positive. Five samples were positive only by Monolisa and 2 only by Ortho (overall agreement: 99.5%). Group 2: Results were concordant in 325 samples, 308 negative and 17 positive. Seven samples were positive by Monolisa and negative by Ortho. The sensitivity of the Monolisa test in hemodialysis patients was clearly higher than that of the Ortho test (100% and 70.8%, respectively). Monolisa detected HCV infection in 43 of 75 samples from the seroconversion panels; only 18 positive samples were detected by Ortho HCV. Monolisa reduced the window period by up to 72 days.

CONCLUSIONS

Our data indicate high agreement between the Monolisa and Ortho tests in samples from the general population. In hemodialysis patients, however, Monolisa was more sensitive. In addition, the Monolisa test significantly reduced the window period of HCV infection.

Chip-based detection of hepatitis C virus using RNA aptamers that specifically bind to HCV core antigen

The development of reagents with high affinity and specificity to the antigens of hepatitis C virus (HCV) is important for the early stage diagnosis of its infection. Aptamers are short, single-stranded oligonucleotides with the ability to specifically recognize target molecules with high affinity. Herein, we report the selection of RNA aptamers that bind to the core antigen of HCV. High affinity aptamers were isolated from a 10(15) random library of 60 mer RNAs using the SELEX procedure. Importantly, the selected aptamers specifically bound to the core antigen, but not to another HCV antigen, NS5, in a protein chip-based assay. Using these aptamers, we developed an aptamer-based biosensor for HCV diagnosis and detected the core antigen from HCV infected patients' sera with good specificity. This novel aptamer-based antigen detection sensor could be applied to the early diagnosis of HCV infection.

HCV core protein immunization with Montanide/CpG elicits strong Th1/Th2 and long-lived CTL responses

An efficient vaccine against Hepatitis C virus (HCV) infection requires induction of strong humoral and cellular responses against viral proteins. We evaluated the immunogenicity of HCV core protein (HCVcp), a prime vaccine candidate, formulated in various human compatible adjuvants. An Escherichia coli-expressed HCVcp, purified in native conditions was used for murine immunization in separate groups of: free HCVcp (Ag), Ag+C/IFA (Freunds), Ag+CpG, Ag+M720 (Montanide ISA 720), Ag+F127 (Pluronic acid) and cocktails of Ag+F127+CpG and Ag+M720+CpG. Mice immunized with M720(+CpG) developed the highest HCVcp-specific titers of total IgG, IgG1, 2a, 2b, and that of IFN-gamma and IL-4 cytokines compared to all other groups. HCVcp-specific-CTLs against relevant MHC class I peptides were detected only for Ag+M720+CpG, Ag+M720, and Ag+CpG groups and could be blocked by antimouse-CD8 antibodies. While CTLs were stable, only F127 formulated groups demonstrated detectable IgG antibodies one year post-immunization. Hence, HCVcp formulated in M720 (with a synergistic effect by inclusion of CpG) could induce balanced and strong Th1/Th2 responses with long-lived CD4(-)CD8(+) CTLs.

Quantitative measurement of hepatitis C virus core antigen is affected by the presence of cryoglobulins

Mixed cryoglobulinaemia is associated strikingly with HCV infection. The aim of this study was to assess whether the adherence to proper methods of collecting samples for cryoglobulin detection was critical or not on virological parameters in hepatitis C virus (HCV) patients. We studied 56 consecutive patients. Blood samples were collected using a conventional method and a blood collection method at 37 degrees C adapted to cryoglobulin detection. HCV core antigen and HCV RNA were measured in sera and cryoglobulins issued from both blood collection methods. In cryoglobulin-positive patients, serum concentrations of HCV core antigen, but not that of HCV RNA, were significantly higher when a conventional method was used, compared to a blood collection method at 37 degrees C (P = 0.001). In the cryoprecipitates, concentration of HCV core antigen was optimum when the blood collection method at 37 degrees C, rather than the conventional method, was applied for cryoglobulin detection (P < 10(-4)). The recovery of HCV core antigen in the cryoprecipitate was improved when cryoglobulins were isolated using the blood collection method at 37 degrees C rather than the conventional method (P < 0.001). HCV parameter measurements and cryoglobulin study should not be performed on the same serum samples due to the potential impact of blood collection methods on results.

Significance of the hepatitis C virus (HCV) core antigen as an alternative plasma marker of active HCV infection

PURPOSE

To evaluate the role of core antigen (Ortho trak-C assay) as a marker of active HCV infection in comparison to HCV RNA as detected by reverse transcription polymerase chain reaction (RT-PCR).

METHODS

This evaluation was carried out during January 2000 to December 2003 in HCV infected individuals who were treatment naomicronve or were on anti-viral therapy. Additionally, sequential plasma samples from patients on clinical follow-up were included in this study. A total of 167 samples from 61 patients were tested by trak-C and RT-PCR. HCV RNA detection was achieved by a RT-PCR. Trak-C assay results were also compared in a limited proportion of these samples with known HCV viral load and genotype.

RESULTS

Of 167 samples tested, 56.9% were RNA positive and 43.1% were RNA negative while 50.3% were trak-C positive and 49.7% were trak-C negative, yielding a sensitivity of 85.3% and a specificity of 95.8% for the trak-C assay (Kappa co-efficient = 0.8). The concentration of HCVcAg and HCV RNA showed significant correlation (n=38, r=0.334, P =0.04). The trak-C assay detected the most prevalent HCV genotypes in India without significant difference (P =0.335). The difference between mean absorbance values of HCV RNA positive samples compared to HCV RNA negative samples in the trak-C assay was highly significant (P < 0.000). Qualitative results of trak-C assay and RT-PCR were comparable in 93% of follow-up samples.

CONCLUSIONS

Trak-C assay can be recommended for confirmation of HCV infection and follow-up in laboratories with resource-poor facilities.

Value of HCV antigen-antibody combined HCV assay in hepatitis C diagnosis

Reduction of the window period of hepatitis C virus (HCV) infection represents an important goal in the transfusional and diagnostic settings. Currently, the detection of HCV infection relies on the use of immunoassays to detect viral antibodies. A new enzyme immunoassay (Monolisa HCV Ag-Ab ULTRA) designed to simultaneously detect circulating HCV antigen and anti-HCV antibodies has been developed by Bio-Rad and registered by the European Authorities. Several evaluations have been conducted in Europe to determine whether this new assay can improve early detection of HCV infection. Sensitivity studies included 130 HCV RNA positive/anti-HCV negative samples, 21 well documented seroconversion panels and 430 anti-HCV genotyped samples from France and Italy. Specificity has also been assessed in 15,302 non-selected blood donations and hospital samples. Studies have shown that Monolisa HCV Ag-Ab ULTRA assay has been able to detect 40-90 % of HCV RNA positive/anti-HCV negative samples collected in the window period, improving early detection of HCV when antibodies may be undetectable. The mean delay in detecting HCV infection between HCV-RNA and this new test was found to be 5 days, reducing the window period by an average of 37 days. All samples collected after seroconversion were detected with the HCV Ag-Ab ULTRA assay. The specificity analyzed in 15,302 random blood donations and hospital samples was estimated at 99.86 %. Although less sensitive than NAT (71 % of HCV RNA positive/anti-HCV negative in window period), this assay could be a reasonable alternative when NAT cannot be used for reasons such as cost, organization, emergency or logistic difficulties.

Direct evidence for immunomodulatory properties of ribavirin on T-cell reactivity to hepatitis C virus

BACKGROUND/AIM

An understanding of ribavirin's beneficial effects on treatment outcome in chronic hepatitis C (CH-C) may help to develop new treatment approaches. Here we investigated whether ribavirin directly affects HCV-specific reactivity of CD4+T-lymphocytes from patients with CH-C.

METHODS

Peripheral blood mononuclear cells from forty HCV RNA positive patients were cultured ex vivo with HCV core, NS3, NS4 alone, and with different concentrations of ribavirin. Virus-specific CD4+ T-cell reactivity was analysed by a proliferation assay; quantitation of cytokine (interferon-gamma, IL-10, IL-5, IL-12p35, IL-12p40) mRNA levels; measurement of interferon-gamma and IL-10 production (by ELISA) and enumeration of interferon-gamma and IL-10 producing T-cells by Elispot assays.

RESULTS

At 2-5 microM ribavirin induced de novo or enhanced T-cell proliferation to HCV antigens in a proportion of patients. Increased T-cell proliferation was associated with decreased IL-10 production in response to HCV core and reduced frequency of IL-10 producing CD4+ T-cells, while interferon-gamma levels remained unchanged. At 20 microM ribavirin markedly suppressed T-cell proliferation, and interferon-gamma mRNA expression to HCV antigens.

CONCLUSIONS

Ribavirin, at clinically achievable plasma levels, modulates directly the T-cell responses to HCV antigens in some CH-C patients. Suppression of IL-10 production may represent a useful strategy to induce/augment T-cell reactivity to HCV.

A chemiluminescent, magnetic particle-based immunoassay for the detection of hepatitis C virus core antigen in human serum or plasma

Hepatitis C virus (HCV) exposure in blood donors is determined serologically by the detection of anti-HCV antibodies in serum or plasma. However, a "window" period of 30-70 days after exposure exists where specific antibodies to HCV antigens are not detected. The use of nucleic acid testing for the detection of HCV RNA or antigen testing for the detection of HCV core protein have resulted in dramatic reductions in the pre-seroconversion window period. In this study, an automated HCV core antigen detection test was developed. This magnetic microparticle-based assay utilizes anti-HCV core monoclonal antibody to capture antigen present in human serum or plasma. Captured antigen is then detected using an anti-HCV core monoclonal antibody conjugated with a chemiluminescent compound. The specificity of this assay was established at 99% upon testing a population of normal volunteer blood donors. Sensitivity was determined by testing 16 commercially available HCV seroconversion panels representing genotypes 1a, 1b, 2b, and 3a. In each panel tested, HCV core antigen was detected prior to anti-HCV antibody, resulting in a reduction of the window period by greater than 23 days on average, and greater than 34 days on panels initially NAT negative. In addition, HCV core antigen was detected in >97% of HCV RNA positive/antibody negative specimens, exhibiting sensitivity nearly equivalent to nucleic acid testing in the pre-seroconversion window period for the panels examined.

[Antigenicity of hepatitis C virus F protein and serum prevalence of anti-F in HCV-infected patients]

OBJECTIVE

To examine the antigenicity of hepatitis C virus (HCV) F protein and investigate serum prevalence of anti-F in HCV-infected patients.

METHODS

Eleven pairs of overlapping primers were used to synthesize the full-length HCV f gene, from which the truncated HCV f65 gene fragment was amplified by PCR. HCV f65 gene was then cloned into pET32a(+), and transformed into E. coli strain Plyss (DE3). This recombinant E.coli was induced by IPTG for the production of HCV F65 protein. The expressed HCV F65 protein, purified by Ni-NTA agarose, was further used in ELISA to detect serum anti-F, and to immunize rabbits for making polyclonal anti-F. The rabbit polyclonal anti-F was purified by Staphylococcus aureus protein A agarose.

RESULTS

After recombinant pET32a(+)-f65 was constructed successfully, HCV F65 protein was expressed and purified. The purified HCV F65 protein was used as a capture antigen in ELISA to detect serum anti-F in HCV infected patients (n = 30). The result showed that the mean A450 value and the positive rate of serum anti-F were 0.125+/-0.061 and 63.3%, respectively. The rabbit-derived polyclonal anti-F reacted specifically with HCV F65 protein, of which the titer was 1:30,000.

CONCLUSION

Our expressed HCV F65 protein is of antigenicity, and can be used to determine serum anti-F. Anti-F IgG does exist in the sera of the HCV-infected patients. Moreover, the rabbit-derived polyclonal anti-F can be used to detect HCV F protein.

[Qualitative detection of hepatitis C virus core antigen in the serum in patients with chronic hepatitis C]

OBJECTIVE

To evaluate the clinical significance of serum hepatitis C virus (HCV) core antigen detected by enzyme linked immunosorbent assay (ELISA).

METHODS

The serum HCV core antigen, which was taken from 149 patients with chronic hepatitis C, 20 patients of chronic hepatitis B and 20 health volunteers, was detected by ELISA. Meanwhile, the serum HCV RNA was detected by RT-PCR, and anti-HCV was detected by ELISA.

RESULTS

The qualitative HCV core antigen in the serum, which was take from 20 patients of chronic hepatitis B and 20 health volunteers, was negative.The positive percentage of HCV core antigen was 49.66% in the 149 sera of patients with chronic hepatitis C. The coincidence of detective results of HCV RNA and HCV core antigen was 54.36%, without significant difference (P>0.05). The positive percentage of HCV RNA and HCV core antigen in the 149 anti-HCV antibody positive sera samples were 55.03% (82/149) and 49.66% (74/149), respectively, and there was no significant difference (P>0.05).

CONCLUSION

The qualitative HCV core antigen detected by ELISA has a high specificity. The positive percentage of HCV core antigen in the serum of patients with chronic hepatitis C is 49.66%. HCV core antigen is related to HCV RNA. HCV core antigen may be a useful serum marker which could show HCV viraemia like HCV RNA.

Combined hepatitis C virus (HCV) antigen-antibody detection assay does not improve diagnosis for seronegative individuals with occult HCV infection

A combined hepatitis C virus (HCV) antigen-antibody assay was evaluated for 115 seronegative individuals with occult HCV infection. The assay was reactive in one patient and negative to weakly reactive in three others (all four gave indeterminate results by supplemental assay) but failed to detect HCV in the remaining patients. Despite increased sensitivity the combined assay does not improve serodiagnosis of occult HCV infection.

Reliability and diagnostic use of a test for the search of the hepatitis C virus Ag (AgHCV)

BACKGROUND/AIMS

The detection of serum HCV nucleocapsid (core) antigen, besides being a valid alternative, by virtue of its low cost, to direct analysis of the virus in everyday transfusion practice, also aims to be employed in monitoring patients subjected to antiviral therapy. The verification of strict correlation between the two tests is the presupposition for such use.

METHODOLOGY

In a group of 112 HCV-positive subjects, we assessed blood transaminases, viremia (by PCR), and the circulating core antigen (by ELISA).

RESULTS

Only 16 out of 112 patients were AgHCV-negative, with viremia levels in the 10(2) to 10(4) range; 96 patients were HCV-positive, as indicated both by viremia and by Ag detection (1.9 to 292.4pg/mL). Sensitivity of the ELISA test corresponds to 3.6x10(4) IU/mL of viral load. There is an evident aggregation of results in groups according to antigenemia classes and the corresponding viremia levels: <10pg/mL--10(4) IU/mL (6/96); up to 100pg/mL--10(5) IU/mL (55/96); 100-200pg/mL--10(6) IU/mL (31/96); and more than 200pg/mL--10(7) IU/mL (4/96).

CONCLUSIONS

AgHCV is correlated with elevation of ALT and high or medium-high viral loads. It can discriminate between ongoing and previous infection and is suitable for monitoring the pharmacological therapy in the presence of sufficiently high viral loads and for evaluating the onset of medium-long-term relapses. Neither the genotypes nor pharmacological therapy appear to affect the comparison of viremia with antigenemia. Moreover, this analysis is cheaper as compared with molecular techniques.