Analysis of discordant test results among five second-generation assays for anti-hepatitis C virus antibodies also tested by polymerase chain reaction-RNA assay and other laboratory and clinical tests for hepatitis

Evaluation and comparison of three different anti-hepatitis C virus antibody tests based on chemiluminescence and enzyme-linked immunosorbent assay methods used in the diagnosis of hepatitis C infections in Turkey

The routine diagnosis of hepatitis C virus (HCV) infection is based on the detection of anti-HCV antibodies by two main methods (enzyme immunoassay [EIA] and chemiluminescence immunoassay [CIA]) but false-positives are a problem. We investigated three anti-HCV tests: two CIAs (Cobas e 601 and Architect i2000SR); and one EIA (Ortho HCV 3.0). Two other anti-HCV tests were also performed as supplementary and confirmatory tests, respectively: a recombinant strip immunoblot assay (RIBA HCV 3.0 SIA) and a reverse transcriptase polymerase chain reaction-based assay for HCV-RNA. After discriminating the false-positive results, the true anti-HCV seropositivity rate in 7156 serum samples was 0.91%. The seropositivity and false-positive rates for the Cobas e 601, Architect i2000SR and Ortho HCV 3.0 anti-HCV tests were 1.9% and 0.99%, 1.2% and 0.29%, and 0.87% and 0.01%, respectively. The mean level of HCV-RNA was 3399 x 10(3) IU/ml. Critical levels for false-positivity for HCV-RNA were a cut-off index of 200 for Cobas e 601, a signal/cut-off (S/CO) of 5 for Architect i2000SR and an S/CO of 1.2 for Ortho HCV 3.0. Positive and negative results for the RIBA HCV 3.0 SIA assay all accorded with the HCV-RNA assay, except for 23 (17%) 'indeterminate' results, all of which were negative with the HCV-RNA assay. In conclusion, to eliminate doubts related to false-positive findings in the initial HCV screening tests, additional confirmatory HCV-RNA assay should be performed.

Hepatitis and reproduction

This bulletin will review the various viral etiologies of hepatitis, their mode of transmission, and implications for infertile couples, pregnant women, and health care workers.

Antibodies to hepatitis C and other viral markersin multi-transfused patients from Argentina

BACKGROUND

The knowledge of transfusion-transmitted viral infections in Argentina is scarce. A regional study organized by the Pan American Health Organization let us asses the current status.

OBJECTIVES

To estimate the prevalence of HCV, HBV and HIV infection in a population of multi-transfused Argentinean patients.

STUDY DESIGN

Multi-center, cross sectional study of 504 patients from national referral institutions in Buenos Aires, who had received more than ten units of blood products in more than two occasions. Demographic and clinical data were collected using a standardized questionnaire. Blood samples were analyzed for a-HCV, a-HIV, HBsAg and a-HBcore.

RESULTS

Patients belonged to five diagnostic categories: onco-hematology (309; 61.3%); hemophilia (96; 19%); acute blood loss (54; 10.7% ); hemoglobinopathies (35; 6.9%); and hemodialysis (5; 1% ); five patients (1%) had two of the previous conditions. Overall prevalence rates of viral markers were: a-HCV 9.3% (CI(95%): 6.7-12.0); a-HBcore 4.8% (CI(95): 2.8-6.7); a-HIV 1.2% (CI(95%): 0.14-2.2) and HBsAg 0.20%(CI(95%): 0.2-0.59). The highest prevalence rates were found among patients living with hemophilia (PLH). There was a significant statistical association (p < 10(-5), OR =78.8 [29.7-209.7]) between a-HCV infection and having been transfused before 1993, when screening blood donors for a-HCV became mandatory in our country. The subpopulation of patients exposed to transfusion before 1993 was conformed mostly by PLH (70.9%) and hemoglobinopathies (18.6%). In this subpopulation, we found a significant association (p < 10(Dot;), OR -40 [5.68-281.66]) between years of exposure to transfusion and a-HCV among the patients under the median age (21.95 years old); however, there was no association for those above the median age (p=0.111).

CONCLUSION

a-HCV was found to be the most prevalent infection in the multi-transfused patient population under study. Most infected individuals were PLH, transfused before 1993. This study will provide support for further research aimed at improving blood safety in Argentina.

Impact of hepatitis C infection on long-term mortality of injecting drug users from 1990 to 2002: differences before and after HAART

OBJECTIVE

To assess the impact of HIV and hepatitis C virus (HCV) infection on long-term mortality in injecting drug users (IDU).

DESIGN

Community-based prospective cohort study.

METHODS

Mortality data from follow-up in clinical sites and the Mortality Registry by December 2002 were collected for 3247 IDU who attended three centres for voluntary counselling and testing for HIV/AIDS, HCV and hepatitis B virus (HBV) in 1990-1996. Mortality rates by Poisson regression were adjusting for age, sex, duration of drug use, education, HBV and calendar period (1990-1997 and 1998-2002).

RESULTS

Overall, 11.2% were HIV/HCV negative, 43.7% positive only for HCV and 45.1% positive for both. During 26 772 person-years of follow-up, 585 deaths were detected (2.19/100 person-years). Before 1997, HIV/HCV-positive subjects had a five-fold increase in risk of death [relative risk (RR), 5.4; 95% confidence interval (CI), 2.5-11.4] compared with those negative for both; after 1997, a three-fold increase was observed (RR, 2.7; 95% CI, 1.7-4.2). Being HCV positive/HIV negative was not associated with an increase in the risk of death either before (RR, 1.3; 95% CI, 0.6-2.9) or after (RR, 1.2; 95% CI, 0.8-1.9) 1997 compared with HCV/HIV negative. While increases in mortality were seen in those HCV/HIV negative (RR, 1.6; 95% CI, 0.7-3.7) and those only positive for HCV (RR, 1.5; 95% CI, 1.0-2.1), a 20% reduction among coinfected IDUs was observed after 1997 (interaction P = 0.033).

CONCLUSIONS

HCV/HIV coinfection has had a large impact on mortality in IDU. After 1997, mortality increased in HIV negative/HCV positive subjects and decreased in HIV positive/HCV positive.

Prevalence and risk factors associated with hepatitis C in ED patients

The objective of this study was to measure the prevalence of and identify risk factors associated with hepatitis C virus (HCV) in emergency department (ED) patients. Adults presenting to an urban university teaching hospital, having blood drawn as part of their routine evaluation, had an extra tube drawn and tested for HCV. English-speaking adults consenting to participate in the survey portion of the study were administered an in-depth risk factor questionnaire. A case-control analysis was used to identify risk factors in HCV+ compared with HCV- subjects. Contingency table analyses using the Fisher exact test, odds ratios (OR), and 95% confidence intervals (CI) were used for risk factor identification. Of 223 blood samples, 38 (17%) were positive for antibodies for HCV. One hundred twenty-one subjects (54%) agreed to the risk factor survey, 18 (15%) of whom were HCV+. Of the 18 HCV+ survey participants, 12 new diagnoses of HCV were made. A history of injection drug use was the most significant risk factor associated with HCV (OR 858.5, CI 61.8-22,026.5). A high prevalence of HCV is found in selected urban ED patients. Most of these patients have a constellation of risk factors including a history of injection drug use. Efforts to identify at risk patients for serologic testing and follow-up should be initiated. Identifying undiagnosed HCV can lead to interventions to decrease transmission as well as reduce the morbidity and mortality of disease.

Comparison of second- and third-generation enzyme immunoassays for detecting antibodies to hepatitis C virus

Supplemental assays, such as recombinant immunoblot assays (RIBA), are used to confirm detection of antibodies to hepatitis C virus (HCV). However, due to their expense, they are not widely used in developing countries. The purpose of our study was to compare the results of second- and third-generation (G2 and G3, respectively) enzyme immunoassays (EIAs) and to resolve discordant results by using a supplemental assay to assess the reliability of G2 and G3 EIAs to confirm anti-HCV antibody-positive results. We performed both G2 and G3 EIAs for anti-HCV antibodies on 1,134 serum samples collected during the 2nd year of a longitudinal community-based study in Egypt; 35 samples with discordant results were tested by Abbott Laboratories Micro-Particle Immunoassay (M-EIA) and RIBA. Viremia was determined with an in-house nested reverse transcriptase PCR (RT-PCR) to detect HCV RNA. Concordance between the two assays (G2/G3) was 96.9%; 87 (7.7%) samples were positive and 1,012 (89.2%) were negative by both assays. For 17 samples, the discordant results were G2 assay negative and G3 assay positive, and for 18 samples, the discordant results were G2 assay positive and G3 assay negative. Among the 17 G2 assay-negative and G3 assay-positive samples, 15 were M-EIA positive and 7 were PCR positive. Among the 18 G2 assay-positive and G3 assay-negative samples, 2 were M-EIA positive and none were PCR positive. RIBA results from 24 discordant samples showed 87.5% agreement with the G3 EIA, 12.5% agreement with the G2 EIA, and 95.8% agreement with M-EIA. Eleven samples were indeterminate by RIBA and excluded from this analysis. Based on RIBA results, the sensitivity of the G3 EIA was 99%, compared to 89.8% for the G2 EIA, while the specificity of the G3 EIA was 99.8%, compared to 98.9% for the G2 EIA. These results show that the reliability of the G3 EIA in screening these sera is excellent, and the G3 assay can be used in the absence of supplemental tests where resources are limited. RIBA appears not to have advantages over the less expensive M-EIA screening assay. The main disadvantage of RIBA is the occurrence of indeterminate results, especially among problematic samples. Samples giving discordant results in multiple assays are often indeterminate with the RIBA.

Immunopathogenesis of hepatitis C virus infection

Hepatitis C virus, a recently identified member of the family Flaviviridae, is an important cause of chronic viral hepatitis and cirrhosis. There are similarities in the nature of the immune response to this pathogen with immunity in other flavivirus and hepatotropic virus infections, such as hepatitis B. However, the high rate of viral persistence after primary hepatitis C infection, and the observation that neutralizing antibodies are not protective, would suggest that there are a number of important differences between hepatitis C, other flaviviruses, and hepatitis B. The phenomenon of quasispecies evolution and other viral factors have been proposed to contribute to immune evasion by hepatitis C virus. In the face of established persistent infection, virus-specific cytotoxic T lymphocytes may exert some control over viral replication. However, these same effectors may also be responsible for the progressive liver damage characteristic of chronic hepatitis C infection. The nature of protective immunity, including the role of innate immune responses early after hepatitis C exposure, remains to be defined.

Molecular diagnostics of infectious diseases

Over the past several years, the development and application of molecular diagnostic techniques has initiated a revolution in the diagnosis and monitoring of infectious diseases. Microbial phenotypic characteristics, such as protein, bacteriophage, and chromatographic profiles, as well as biotyping and susceptibility testing, are used in most routine laboratories for identification and differentiation. Nucleic acid techniques, such as plasmid profiling, various methods for generating restriction fragment length polymorphisms, and the polymerase chain reaction (PCR), are making increasing inroads into clinical laboratories. PCR-based systems to detect the etiologic agents of disease directly from clinical samples, without the need for culture, have been useful in rapid detection of unculturable or fastidious microorganisms. Additionally, sequence analysis of amplified microbial DNA allows for identification and better characterization of the pathogen. Subspecies variation, identified by various techniques, has been shown to be important in the prognosis of certain diseases. Other important advances include the determination of viral load and the direct detection of genes or gene mutations responsible for drug resistance. Increased use of automation and user-friendly software makes these technologies more widely available. In all, the detection of infectious agents at the nucleic acid level represents a true synthesis of clinical chemistry and clinical microbiology techniques.

Viral replication in patients with concomitant hepatitis B and C virus infections

The aim of this study was to assess the implications of dual infection with hepatitis B virus (HBV) and hepatitis C virus (HCV). The HBV and HCV status in 100 patients with chronic hepatitis was analysed. HBV DNA was studied using liquid hybridization and the polymerase chain reaction (PCR). HCV viremia was measured using qualitative and quantitative PCR. The HCV genotype was determined by PCR. Patients were divided into three groups according to their HCV-RNA and HBsAg status: group I consisted of 40 patients with chronic hepatitis caused by HBV; group II, 40 patients with chronic hepatitis caused by HCV; and group III, 20 patients infected with both viruses. The HBV-DNA level was higher in group I than in group III (66.4 vs. 11.5 pg/ml; p < 0.05). Quantification of HCV viremia revealed mean values of 36.9 copies x 10(5)/ml in group II and 5.5 copies/ml x 10(5) in group III (p < 0.05). The mean aminotransferase level and histological activity were higher in group III. HCV genotype lb was the predominant type. The data suggest that there is reciprocal inhibition of viral replication in patients with dual HBV and HCV infection. Liver disease appears to be more severe in patients with chronic hepatitis B and C.

Quantitation of anti-hepatitic C virus antibodies in interferon-treated patients by S29-1/S4 ELISA

In 23 patients with chronic hepatitis C who have undergone interferon (IFN) treatment, quantitation of anti-hepatitis C virus IgG antibodies by a second-generation assay S29-1/S4 ELISA [Sato et al. (1993): Microbiology and Immunology 37: 295-304]. (anti-S29-1/S4) was compared with that of anti-HCV core IgG antibodies (C22-3, anticore) and the presence of viral RNA confirmed by the reverse transcription-nested polymerase chain reaction (RT-nested PCR). In 12 complete responders with loss of HCV-RNA and normal alanine aminotransferase (ALT) levels at 6 months after therapy, IgG antibodies quantified by a second-generation assay have decreased significantly at the end of treatment (P < 0.05). Further significant reduction of anti-S29-1/S4 titers was observed at 6 months after therapy (P < 0.01) as well as anti-core antibodies (P < 0.01). On the other hand, in 11 non-responders with persistent or intermittent viremia at 6 months after therapy, no significant change in the level of anti-S29-1/S4 titers was observed, whereas anti-core titers have decreased at the end of therapy (P < 0.01). In contrast, both levels of anti-S29-1/S4 and anti-core have increased at 6 months after treatment (P < 0.05). It is concluded that, although it appears difficult to monitor the effect of virus clearance during IFN therapy, changes in anti-S29-1/S4 titers after IFN treatment correlate with virus clearance and with anti-core titers.

Preclinical evaluation of AMPLICOR hepatitis C virus test for detection of hepatitis C virus RNA

We compared a single-enzyme, combined reverse transcription-PCR (RT-PCR; AMPLICOR HCV Test; Roche Molecular Systems, Branchburg, N.J.) with an independent, two-enzyme, standard RT-PCR (SRT-PCR) assay for the detection of hepatitis C virus (HCV) RNA in serum and plasma. Test samples included a proficiency testing panel consisting of 10 undiluted plasma samples, three separate dilution series, and sera from 99 patients with chronic liver disease. The quantity of HCV RNA in each patient serum sample was determined by a branched DNA (bDNA) signal amplification assay (Quantiplex HCV-RNA assay; Chiron, Emeryville, Calif.). There was complete concordance between the results of the RT-PCR assays with the 10 undiluted plasma samples used for proficiency testing (3 positive and 7 negative samples). However, the analytical sensitivity of SRT-PCR was 4- to 10-fold greater than that of the AMPLICOR test in the dilution series. HCV RNA was detected in 44, 45, and 40 of the patient serum samples, by SRT-PCR, the AMPLICOR test, and the bDNA assay, respectively. There was 97% agreement between the results of the RT-PCR assays, with only three discrepancies. Review of the patients' medical records resolved all three discrepancies in favor of the AMPLICOR results (two false-negative SRT-PCR results and one false-positive SRT-PCR result). The quantity of HCV RNA in sera from five (11%) patients with viremia detected by AMPLICOR was below the bDNA assay cutoff (< 3.5 x 10(5) RNA equivalents per ml). AMPLICOR compared favorably with SRT-PCR, with key advantages of speed, ease of use, increased sample throughput, and protection against false-positive results because of amplicon carryover.

ELISA for anti-HCV antibody employing a shorter synthetic core region peptide

A new ELISA for anti-HCV antibody was developed employing a shorter synthetic N-terminal peptide, 2-62aa, within the core region of 1-191aa. The basic performance of the assay was comparable to three other second-generation assays using longer HCV core antigens. To evaluate assay performance at the borderline level, 25 samples with indeterminate results were selected from 3000 routine serum samples. Only 5 of the 25 sera were found to be HCV-RNA-positive by a nested PCR assay and with apparent clinical evidence of HCV infection. The results of the new ELISA agreed with those of the PCR-RNA test in 23/25 (kappa statistics 0.75), whereas C22-3 of the RIBA II test using 2-120aa of the core agreed in 9/25 (0.09), the Abbott pHCV-34 EIA test using 1-150aa agreed in 10/25 (-0.12), and a neutralization inhibition assay for Abbott EIA II using 2-120aa agreed in 6/25 (0.02). These results indicate that the UBI CORE ELISA has greatly improved specificity and can be a useful indication of viremia in HCV infection.

Molecular detection of hepatitis C virus: impact of detection methodology on clinical and laboratory correlations

The clinical manifestations of hepatitis C virus (HCV) infection are generally indistinguishable from other causes of viral hepatitis. HCV infections are usually anicteric, asymptomatic, and rarely cause acute fulminant liver failure. Serological testing for HCV in conjunction with epidemiological studies have verified that HCV was the major cause of parenterally transmitted non-A, non-B hepatitis (NANBH). With the widespread introduction of serological screening of blood products for HCV antibody, the risk of transfusion-associated HCV infection has been dramatically reduced (to < 3 cases per 10,000 units transfused). Despite the virtual elimination of transfusion-associated infections, the diagnosis of HCV remains important because > 50% of infections are sporadic in origin, 50 to 70% of infected individuals develop chronic hepatitis, and these individuals are at risk of developing cirrhosis (> 20%) as well as hepatocellular carcinoma. Although currently available anti-HCV immunoassays function well as blood-donor screening assays, they are poor at detecting acute infection because of the prolonged lag time between infection and detection of seroconversion (approximately 10 to 26 weeks for second-generation immunoassays). In contrast, polymerase chain reaction (PCR)-based detection of HCV RNA in serum can detect infection in as little as 1 to 2 weeks after exposure. This review focuses on the impact of modern serologic and nucleic acid-based HCV detection methodology on the clinical understanding of HCV infection, its associated illnesses, and its transmissability. Quantitative and reproducible nucleic acid-based detection assays will be required to provide additional insights into the clinical spectrum of HCV infections as well as to assess the efficacy of antiviral agents.

Analysis of sera indeterminate by Ortho-HCV RIBA-2 by using three confirmatory assays for anti-hepatitis C virus antibody

The diagnostic performances of three commercially available recombinant immunoblot assays (RIBAs) for anti-hepatitis C virus antibody were evaluated on 50 ORTHO-HCV RIBA-2 (RIBA-2)-indeterminate serum samples. Concordant interpretations were obtained with the three tests in 60% of the samples, with 56% positive, 2% indeterminate, and 2% negative results. Considering test performance in regard to the number of remaining indeterminate results, analyzing sera by RIBA-3, INNO-LIA HCV Ab III, and DECISCAN HCV reduced the number of samples reacting indeterminately to 40, 6, and 8%, respectively. The three serum samples classified as indeterminate in the INNO-LIA HCV Ab III as well as three of four serum samples interpreted as indeterminate in the DECISCAN HCV and 16 of 20 samples classified as indeterminate in the RIBA-3 were hepatitis C virus RNA positive by PCR. This study clearly shows the good performance of the three tests as confirmatory assays compared with that of the RIBA-2. However, according to the manufacturers' criteria of positivity, the INNO-LIA HCV Ab III and DECISCAN HCV appeared to be more suitable than the RIBA-3 for interpreting serum samples found indeterminate in the RIBA-2.