The significance of third-generation HCV RIBA-indeterminate, RNA-negative results in voluntary blood donors screened with sequential third-generation immunoassays

False positive viral marker results in blood donors and their unintended consequences

False positive (FP) viral marker results in blood donors continue to pose many challenges. Informing donors of FP results and subsequent deferral can result in stress and anxiety for donors and additional complexity and workload for blood services. Donor management strategies need to balance the requirement to minimise donor anxiety and inconvenience while maintaining sufficiency of supply. Decisions about how and when to inform donors of FP results and determine deferral periods can be difficult as FP results, while often transitory, can take up to several years to resolve. Additional complexities include the interpretation of indeterminate serological confirmatory testing without detectable viral RNA or non-discriminated NAT results with concomitant anti-HBc reactivity - both may be due to FP results, but the former may also represent past infection and the later may represent occult hepatitis B infection. In this review we discuss strategies to minimise indeterminate serological confirmatory results, possible donor deferral policies and the impact on donors when notified of FP results. We also provide some new data from Australia that address the challenge of interpreting non-discriminated NAT results with concomitant anti-HBc reactivity. Ultimately, the challenge is for each blood service to develop appropriate strategies for donor management, taking into account local information and requirements.

Anti-HCV immunoblot indeterminate results in blood donors: non-specific reactivity or past exposure to HCV?

BACKGROUND AND OBJECTIVE

The significance of anti-HCV immunoblot (IB) indeterminate results can be difficult to determine. We analysed results for blood donors tested on the MP Diagnostics HCV Blot 3.0 IB assay to determine whether indeterminate results representing past exposure to HCV could be distinguished from those due to non-specific reactivity.

MATERIALS AND METHODS

Results for all donors tested by IB during the study period (July 2010 to December 2013) were included in this study.

RESULTS

Of 131 donors tested by IB, 34 (26.0%) were negative, 38 (29.0%) were indeterminate, and 59 (45.0%) were positive. There was no significant difference in IB band reactivity strength between indeterminate and positive donors. The PRISM HCV chemiluminescent immunoassay (ChLIA) sample to cut-off (s/co) ratio distribution for the indeterminate donors was significantly higher than for those with biological false reactivity (P = 0·037), but significantly lower than for donors who were IB positive/HCV RNA negative (P < 0·001) or IB not tested/HCV RNA positive (P < 0·001). Of donors available for follow-up, 53.1% of the indeterminate group disclosed a putative risk factor for HCV infection compared to 39.4% (P < 0·001) for the IB-negative group, 76.6% (P = 0·065) for the IB-positive group and 83.4% (P < 0·001) for the HCV RNA-positive group.

CONCLUSION

The results of this study indicate that PRISM ChLIA s/co ratios >2·00 with IB indeterminate results predict exposure to HCV, particularly in the presence of putative risk factors for HCV infection. These findings may be applied to optimizing counselling of donors with indeterminate HCV results.

Evaluation of the VIDAS Anti-HCV Assay for Detection of Hepatitis C Virus Infection

BACKGROUND

Anti-hepatitis C virus antibody (anti-HCV) assays are recommended for screening HCV-infected persons. The VIDAS Anti-HCV Assay (bioMérieux, France), based on the enzyme-linked fluorescence test principle, was recently introduced in Korea. We evaluated the clinical performance of the VIDAS assay.

METHODS

One hundred HCV-positive and 1,002 HCV-negative blood samples confirmed by Architect anti-HCV (Abbott Laboratories, USA) and COBAS TaqMan HCV real-time PCR (Roche Diagnostics, USA) or the Procleix Ultrio Plus Assay (Gen-Probe Incorporated, USA) were obtained from the Human Serum Bank (HSB) and tested by VIDAS. In case of discrepant results, we conducted a recombinant immunoblot assay (RIBA).

RESULTS

The agreement rates for known HCV-positive and HCV-negative samples between the VIDAS assay and the HSB testing were 100% (95% confidence interval [CI]: 96.4-100%) and 99.5% (95% CI: 98.8-99.8%), respectively. One of the five discrepant samples was positive for Core 2+ and NS3-2 2+ reactivity, two samples were negative, and the other two were indeterminate regarding NS4 2+ reactivity in RIBA. We observed a significant but weak positive correlation between the titers of VIDAS and Architect assays (r=0.315, P<0.001).

CONCLUSIONS

The VIDAS anti-HCV assay, developed on the VIDAS automated immunoassay platform based on the ready-to-use, single-sample test concept may be useful in small-to-medium-sized laboratories. It showed good agreement with Architect anti-HCV and COBAS PCR assays and is therefore useful for detection of HCV infection. Weakly test-positive (ambiguous) samples require additional testing by another anti-HCV, RIBA, or HCV RNA assay.

Utilization of Signal-to-Cutoff Ratio of Hepatitis C Virus Antibody Assay in Predicting HCV Viremia among Hemodialysis Patients

BACKGROUND

Hepatitis C virus (HCV) infection is a common cause of acute and chronic hepatitis among the hemodialysis population. To prevent cross infection between hemodialysis patients during the hemodialysis procedure, routine screening of anti-HCV antibody is recommended. However, a reactive anti-HCV EIA test is not equal to active HCV infection. An expensive RT-PCR study is required to confirm HCV viremia. This will significantly increase the cost burden because payment for each hemodialysis treatment is very low in Taiwan. Thus, it is useful to identify parameters that could predict HCV viremia among anti-HCV-reactive patients. In this study, we examined the usefulness of signal-to-cut (S/CO) ratio of anti-HCV antibody in discriminating HCV viremia from non-viremia among the anti-HCV-reactive hemodialysis population.

MATERIALS AND METHODS

In a cross-sectional measurement of anti-HCV antibody among 369 chronic hemodialysis patients, 44 showed reactive and 9 grey zone reaction for anti-HCV. These 53 patients underwent further blood tests for the measurement of AST, ALT and HCV RNA (by RT-PCR). The results of RT-PCR were used as a dependent variable. Then, S/CO ratios of anti-HCV, serum AST, ALT levels, age and duration of hemodialysis were used as independent variables to undergo ROC curve and logistic regression analysis.

RESULTS

Thirty-six of the 53 reactive and grey zone patients were positive for HCV RNA in the RT-PCR study. Patients who were positive for HCV RNA had a higher S/CO ratio (p < 0.01), higher AST and ALT levels (p < 0.01), and longer duration on hemodialysis (p < 0.05) than those negative for HCV RNA. Logistic regression revealed that only S/CO ratio was a significant predictor for HCV viremia (p = 0.004). ROC curve analysis showed that S/CO ratio had a highest area under curve (0.967, p < 0.001), followed by ALT (0.826, p < 0.001), AST (0.778, p = 0.001), duration on hemodialysis (0.606, p = 0.215) and age (0.426, p = 0.386) in discriminating HCV viremia from non-viremia. Using a cutoff S/CO ratio of 65, we can confirm HCV viremia with a diagnostic specificity of 100%, sensitivity of 80.1% and positive predictive value of 100%.

CONCLUSION

S/CO ratio is a useful indicator in predicting HCV viremia among anti-HCV-reactive hemodialysis patients. Patients with an S/CO ratio >65 can be regarded as those with active HCV infection. Alternatively, patients with reactive anti-HCV but with an S/CO ratio <65 should receive further RT-PCR test.

Protection against hepatitis C infection via NK cells in highly-exposed uninfected injecting drug users

BACKGROUND & AIMS

HCV seroprevalence surveys in longstanding injecting drug users (IDUs) reveal a small minority who remain seronegative, with some exhibiting HCV-specific cellular immunity. This study aimed to characterise this immunity, assess associations with risk behaviours and protection against infection.

METHODS

A nested case-control series from a prospective cohort of seronegative IDUs was selected with incident cases (IN; n = 28) matched by demographics and risk behaviour to exposed uninfected (EU) subjects (n = 28). Samples were assayed for natural killer (NK) cell phenotypes and function, HCV-specific IFNγ in ELISpot, and HCV-specific CD4 T effector responses. IL28B and HLA-C/KIR2DL3 genotypes were tested.

RESULTS

Numbers of activated (CD69(+)) NK cells in the mature CD56(dim)CD16(+) subset, and cytotoxic (NKp30(+)) cells in the CD56(bright)CD16(+) subset were higher in the EU subjects (p = 0.040, p = 0.038 respectively). EU subjects had higher frequencies of interferon gamma (IFNγ) producing NK cells, and lower frequencies of CD107a expression (p = 0.003, p = 0.015 respectively). By contrast, the frequency, magnitude, and breadth of HCV-specific CD4 and CD8 T cell responses did not differ, nor did IL28B, HLA-C, or KIR2DL3 allele frequencies.

CONCLUSIONS

Sustained NK cell activation contributes to protection against HCV infection. HCV-specific cellular immunity is prevalent in EU subjects but does not appear to be protective.

Improving the safety of blood transfusion by using a combination of two screening assays for hepatitis C virus

BACKGROUND AND OBJECTIVES

To illustrate that the combination of a single nucleic acid amplification test (NAT) with a single immunoassay for hepatitis C virus (HCV) detection, as proposed internationally, may lead to the omission of anti-HCV reactive sera with non-reactive NAT results.

MATERIALS AND METHODS

In total, 822 of 519, 299 serum samples from 11 blood centres in China were retested for anti-HCV by using 10 screening assays to detect HCV antibodies. A recombinant immunoblot assay (RIBA HCV 3·0; Ortho-Clinical Diagnostics) was performed to define confirmed HCV infection status. Samples with positive or indeterminate RIBA-HCV results were tested by quantitative tests for HCV RNA (Roche Diagnostics).

RESULTS

We found that 47 of the 822 (5·72%) serum samples were RIBA-positive without detectable HCV RNA. For these samples, the 10 anti-HCV immunoassays gave discordant and unsatisfactory results (detection rate ranging from 10·64 to 34·04%; ratio per 100 000 donations ranging from 5·97 to 8·09). Compared with a single anti-HCV screening assay, the two-assay combination increased the detection of these samples. The five best combinations [Sorin and Lizhu enzyme immunoassays (EIAs), Ortho and Lizhu EIAs, Sorin and Wantai EIAs, Sorin EIA and Roche CIA and Ortho and Wantai EIAs] increased the detection rate from 46·81 to 55·57%, thus reducing the ratio per 100 000 donations of HCV-seropositive samples.

CONCLUSION

The combination of two anti-HCV screening immunoassays in parallel with an HCV NAT is a better strategy for HCV detection in blood centres to improve the safety of blood transfusion.

Indeterminate RIBA results were associated with the absence of hepatitis C virus RNA (HCV-RNA) in blood donors

INTRODUCTION

Hepatitis C virus (HCV) infection is diagnosed by the presence of antibodies and is supplemented by confirmatory testing methods, such as recombinant immunoblot assay (RIBA) and HCV-RNA detection. This study aimed to evaluate the efficacy of RIBA testing to diagnose HCV infection in blood donors positive for anti-HCV antibodies.

METHODS

A total of 102 subjects positive for anti-HCV determined by enzyme-linked immunosorbent assay (ELISA) at the Hematology and Hemotherapy Foundation of Bahia (HEMOBA) were later assessed with new samples using the Abbott Architect anti-HCV test (Abbott Diagnostics, Wiesbaden, Germany), the RIBA III test (Chiron RIBA HCV 3.0 SIA, Chiron Corp., Emeryville, CA, USA), the polymerase chain reaction (PCR; COBAS® AMPLICOR HCV Roche Diagnostics Corp., Indianapolis, IN, USA) and line probe assay (LiPA - Siemens, Tarrytown, NY, USA) genotyping for HCV diagnosis.

RESULTS

Of these new samples, 38.2% (39/102) were positive, 57.8% (59/102) were negative and 3.9% (4/102) were indeterminate for anti-HCV; HCV-RNA was detected in 22.5% (23/102) of the samples. RIBA results were positive in 58.1% (25/43), negative in 9.3% (4/43) and indeterminate in 32.6% (14/43) of the samples. The prevailing genotypes were 1 (78.3%, 18/23), 3 (17.4%, 4/23) and 2 (4.3%, 1/23). All 14 samples with indeterminate RIBA results had undetectable viral loads (detection limit ≤50 IU/mL). Of these samples, 71.4% (10/14) were reevaluated six months later. Eighty percent (8/10) of these samples remained indeterminate by RIBA, and 20% (2/10) were negative.

CONCLUSIONS

In this study, individuals with indeterminate RIBA results had no detectable HCV-RNA.

Enzyme-linked immunosorbent/chemiluminescence assays, recombinant immunoblot assays and nucleic acid tests in the diagnosis of HCV infection

The diagnosis of hepatitis C virus (HCV) infection is defined according to the results obtained from screening assays, and confirmation made by supplemental tests, in order to exclude the possibility of false-positive and false-negative results and, therefore, a misdiagnosis. Identifying the patient's true clinical status is of crucial importance to direct an accurate course of therapy, but, often, the definition of this status is only possible after conjunctions and analysis of the results obtained from each methodology applied, considering the limitations of each assay. In this manuscript, it is discussed briefly the possible results obtained from the three methods most commonly applied in routine laboratory and their contribution in the diagnosis of HCV infection.

HBV, HCV and HIV seroprevalence among blood donors in Istanbul, Turkey: how effective are the changes in the national blood transfusion policies?

The national blood transfusion policies have been changed significantly in recent years in Turkey. The purpose of this study was to determine the prevalence of HBV, HCV, and HIV in blood donors at the Red Crescent Center in Istanbul and to evaluate the effect of changes in the national blood transfusion policies on the prevalence of these infections. The screening results of 72695 blood donations at the Red Crescent Center in Istanbul between January and December 2007 were evaluated retrospectively. HBsAg, anti-HCV, and anti-HIV-1/2 were screened by microparticle enzyme immunoassay (MEIA) method. Samples found to be positive for anti-HIV 1/2 and anti-HCV were confirmed by Inno-Lia HCV Ab III and Inno-Lia HIV I/II Score, respectively. The seropositivity rates for HBsAg, anti-HCV, and anti-HIV-1/2 were determined as 1.76%, 0.07%, and 0.008%, respectively. Compared to the previously published data from Red Crescent Centers in Turkey, it was found that HBV and HCV seroprevalances decreased and HIV seroprevalance increased in recent years. In conclusion, we believe that the drop in HBV and HCV prevalence rates are likely multifactorial and may have resulted from more diligent donor questioning upon screening, a higher level of public awareness on viral hepatitis as well as the expansion of HBV vaccination coverage in Turkey. Another factor to contribute to the decreased prevalence of HCV stems from the use of more sensitive confirmation testing on all reactive results, thereby eliminating a fair amount of false positive cases. Despite similar transmission routes, the increase in HIV prevalence in contrast to HBV and HCV may be linked to the increase in AIDS cases in Turkey in recent years.

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.

Analysis of sample-to-cutoff ratios on chemiluminescent immunoassays used for blood donor screening highlights the need for serologic confirmatory testing

BACKGROUND

High sample-to-cutoff (s/co) ratios on hepatitis C virus antibody (anti-HCV) screening immunoassays (IAs) are indicative of confirmed-positive results and, according to some reports, can be used to determine anti-HCV status without the need for confirmatory testing. The purpose of this study was to determine whether s/co ratios on hepatitis B surface antigen (HBsAg), antibody to human immunodeficiency virus Types 1 and 2 (anti-HIV-1/2), anti-HCV, and antibody to human T-lymphotropic virus Types I and II (anti-HTLV-I/II) chemiluminescent immunoassays (ChLIAs) can be used to discriminate between biologic false-reactive (BFR) and confirmed-positive results.

STUDY DESIGN AND METHODS

In a blood donor population the s/co ratio distributions for BFR and confirmed-positive results were compared for the Abbott PRISM HBsAg, HIV O Plus, HCV, and HTLV-I/II ChLIAs to determine the extent of overlap between the two distributions for each assay.

RESULTS

The s/co ratio distributions for BFR and confirmed results overlapped in the range of 10.00 to 60.00, 1.00 to 6.00, 3.00 to 15.00, and 1.00 to 100.00 for the PRISM HIV O Plus, HCV, HTLV-I/II, and HBsAg assays, respectively.

CONCLUSION

Although high s/co ratios were predictive of confirmed-positive results in all four assays, a number of confirmed-positive samples gave low values while some biologic false-positive samples showed high values. As the s/co ratio distributions for BFR and confirmed-positive results overlapped for all four PRISM assays, this study highlights the importance of serologic confirmatory testing and the need for caution when using screening IA results to assign a final donor status.

Clinical performance evaluation of four automated chemiluminescence immunoassays for hepatitis C virus antibody detection

Various automated chemiluminescence immunoassay (CLIA) analyzers for the detection of antibodies to hepatitis C virus (HCV) are now commercially available in clinical laboratories and are replacing conventional enzyme immunoassays. We investigated the performance of four anti-HCV CLIAs (the Architect Anti-HCV assay on the Architect i2000 system, the Vitros Anti-HCV assay on the Vitros ECiQ Immunodiagnostic System, the Access HCV Ab PLUS assay on the UniCel DxI 800 analyzer, and the newly developed Elecsys Anti-HCV assay on the Cobas e 411 analyzer). The total percent coefficient of variation values of imprecision were 3.5 to 5.7% with positive control materials and 7.2 to 10.2% with negative control materials. The agreement between the results of the Elecsys, Architect, Vitros, and Access CLIAs ranged from 94.5 to 98.1%. The clinical sensitivity of all CLIAs was 100%. Each CLIA showed excellent reproducibility and clinical sensitivity. The Elecsys, Architect, Vitros, and Access CLIAs showed clinical specificities of 98.2, 98.8, 96.5, and 98.2%.

Very low hepatitis C antibody levels predict false-positive results and avoid supplemental testing

BACKGROUND

False-positive results for hepatitis C virus antibody (anti-HCV) occur with unacceptable frequency in low-prevalence populations. The purpose of the study was to determine whether signal-to-cutoff (S/CO) ratios of anti-HCV assay-reactive samples could be used to discriminate false-positive from true-positive anti-HCV results and avoid the need for supplemental testing.

STUDY DESIGN AND METHODS

Using receiver-operating characteristic curve, the cutoff point that identifies the major proportion (>/=95%) of false-positive results, with a minor proportion (<5%) of true-positive anti-HCV results, was determined. An anti-HCV assay (VITROS, Ortho Clinical Diagnostics) was used to detect the antibodies. The third-generation recombinant immunoblot assay and HCV RNA tests were performed on all included donors. Third-generation RIBA is the gold standard for identifying false-positive antibody results.

RESULTS

A total of 649 anti-HCV-positive blood donors were identified. A S/CO ratio of less than 4.5, defining very low levels in this value, was the optimal cutoff point to identify false-positive results; 315 of 322 samples with very low levels were false-positive anti-HCV results (97.8%; 95% confidence interval [CI], 95.8%-99.0%) and 7 were true-positive (2.2%; 95% CI, 1.0%-4.3%). Viremia was detected in none of them. A direct relationship was observed between positive supplemental testing and increased antibody levels in the other 327 samples.

CONCLUSION

The high prediction rate of false-positive anti-HCV results using very low levels by the Ortho VITROS anti-HCV assay safely avoids the need for supplemental testing.

Validation of a strategy for HCV antibody testing with two enzyme immunoassays in a routine clinical laboratory

BACKGROUND

Centers for Disease Control (CDC) guidelines require confirmation of hepatitis C virus (HCV) screening-test-positive sera with a low signal/cut-off (S/CO) ratio by recombinant immunoblot or PCR. The UK Health Protection Agency has suggested that a second enzyme immunoassay (EIA) could be used as an alternative for confirmation in non-immunocompromised patients.

OBJECTIVE

To evaluate the UK HPA approach in 17,936 consecutive in-house sera submitted for HCV testing.

STUDY DESIGN

AxSYM-positive sera (S/CO> or =1.0) were tested with Monolisa Plus. AxSYM-positive sera of patients that were confirmed PCR-positive were considered HCV+. All other AxSYM-positive sera were confirmed with immunoblot according to CDC guidelines.

RESULTS

17,299 sera were negative with AxSYM. Of the 637 AxSYM-positive sera, 384 were from patients confirmed as PCR-positive. Of other 250 sera, 120 were negative with immunoblot, 103 were positive and 30 were indeterminate. All 30 immunoblot-indeterminate sera were PCR-negative. Two patients were Monolisa Plus+ and immunoblot- and PCR-. One patient was known as immunoblot-, while the other patient was diagnosed with non-A non-B hepatitis in 1980s. Nine sera from HCV-positive patients were Monolisa Plus-. Two PCR- sera were from immunocompetent patients who were PCR- for > or =8 years and six PCR- sera and one PCR+ serum were from immunocompromised patients. Sensitivity and specificity of confirmation with Monolisa Plus were 98.15% and 98.33% and the positive and negative predictive values were 99.58% and 92.91% in AxSYM-positive sera (excluding immunoblot-indeterminate/PCR-negative sera). If immunocompromised patients that were false-negative were excluded, sensitivity was 99.58%.

CONCLUSION

Monolisa Plus can be used as an alternative to immunoblot for the confirmation of AxSYM-positive sera.

Hepatitis C infection and risk of malignant lymphoma

The association between hepatitis C virus (HCV) infection and risk of malignant lymphoma remains controversial, perhaps due to small-sized studies and low prevalence of HCV in the general population. On the basis of a large Danish-Swedish population-based case-control study, 2,819 lymphoma patients and 1,856 controls of second-generation Danish-Swedish origin were screened for HCV infection using an enzyme-linked immunosorbent assay and a confirming recombinant immunoblot assay (RIBA) test. Positive samples were tested with real-time PCR for the presence of HCV RNA. The association between HCV infection and risk of malignant lymphoma was assessed by logistic regression. When intermediate RIBA test results were interpreted as positive, anti-HCV antibody positivity was associated with a nonsignificant increased risk of non-Hodgkin lymphoma (NHL) overall (odds ratio (OR) = 2.2; 95% confidence interval (CI) 0.9-5.3; n = 20 cases), of B-cell lymphomas combined (OR = 2.4 [1.0-5.8]; n = 20) and of lymphoplasmacytic lymphoma (OR = 5.2 [1.0-26.4]; n = 2). No patients with T-cell or Hodgkin lymphoma were HCV-positive. A more conservative definition of HCV positivity (disregarding intermediate RIBA results) resulted in an OR = 1.6 (0.3-8.5; n = 5) for NHL overall. When the definition was further restricted to require HCV RNA positivity, OR was 1.7 (0.2-16.2; n = 3) for NHL overall. Our findings from a population with a low prevalence of HCV suggest a positive association between HCV and risk of NHL, in particular of B-cell origin.

Cost-effective analysis of different algorithms for the diagnosis of hepatitis C virus infection

We compared the cost-benefit of two algorithms, recently proposed by the Centers for Disease Control and Prevention, USA, with the conventional one, the most appropriate for the diagnosis of hepatitis C virus (HCV) infection in the Brazilian population. Serum samples were obtained from 517 ELISA-positive or -inconclusive blood donors who had returned to Fundação Pró-Sangue/Hemocentro de São Paulo to confirm previous results. Algorithm A was based on signal-to-cut-off (s/co) ratio of ELISA anti-HCV samples that show s/co ratio > or =95% concordance with immunoblot (IB) positivity. For algorithm B, reflex nucleic acid amplification testing by PCR was required for ELISA-positive or -inconclusive samples and IB for PCR-negative samples. For algorithm C, all positive or inconclusive ELISA samples were submitted to IB. We observed a similar rate of positive results with the three algorithms: 287, 287, and 285 for A, B, and C, respectively, and 283 were concordant with one another. Indeterminate results from algorithms A and C were elucidated by PCR (expanded algorithm) which detected two more positive samples. The estimated cost of algorithms A and B was US$21,299.39 and US$32,397.40, respectively, which were 43.5 and 14.0% more economic than C (US$37,673.79). The cost can vary according to the technique used. We conclude that both algorithms A and B are suitable for diagnosing HCV infection in the Brazilian population. Furthermore, algorithm A is the more practical and economical one since it requires supplemental tests for only 54% of the samples. Algorithm B provides early information about the presence of viremia.

Prevalence of low positive anti-HCV antibodies in blood donors: Schistosoma mansoni co-infection and possible role of autoantibodies

Patients infected with schistosoma frequently show a high seroprevalence of anti-hepatitis C virus (anti-HCV) antibodies. The aim of this study was to find the underlying reason for this phenomenon, and to examine a possible involvement of autoantibodies. Out of 2,400 Egyptian blood donors, 192 (8%) were anti-HCV positive by ELISA. They were 133 males and 59 females with age ranging from 27 to 48 years. According to optical density ratio (ODR) of anti-HCV antibodies, 96 cases were low positive (LP) with ODR (1-2) designated as group I, and 96 were high positive (HP) with ODR (> or =2) (group II). Both groups were examined for quantitative HCV core antigen (HCVcAg), liver function (Albumin, ALT, AST) and anti-Schistosoma mansoni(anti-Sm) IgG. Group I cases were HCVcAg negative with normal liver function tests, and 44 of them were anti-Sm positive. Ninety cases (93.75%) of group II were HCVcAg positive with markedly affected liver function tests and 72 cases were anti-Sm positive. All group I cases were examined for autoimmune markers (ANA, AMA, SMA and LKM). In group I, 33 (75%) of anti-Sm positive cases were positive for one or more of the autoimmune markers examined, while none of anti-Sm negative was positive for any marker with significant difference between the two groups (P < 0.0001). Our results primarily on blood donors indicate that LP anti-HCV frequently represents false-positive reactivity with a possible role of Sm-induced autoantibodies in this phenomenon.

Epidemiological, biological and histological characterization of patients with indeterminate third-generation recombinant immunoblot assay antibody results for hepatitis C virus

We studied the epidemiological, laboratory and histological characteristics of a group of patients with positive antibodies against hepatitis C virus (HCV) as determined by third-generation enzyme-linked immunosorbent assay (ELISA), and with indeterminate HCV antibody positivity as established by third-generation recombinant immunoblot assay (RIBA-3). The results obtained were compared with those recorded in a group of RIBA-3-positive patients. Both groups correspond to blood donors in whom the prevalence of hepatitis C is low. There were no statistically significant intergroup differences in mean age, or in the presence of infection risk factors. RNA positivity was much more frequent in the RIBA-positive group (71%vs 10%; P < 0.05), as was transaminase elevation during the 3 years of follow-up (54%vs 13%; P < 0.05). In 46% of the RIBA-indeterminate patients the liver biopsy proved normal, or only liver steatosis or minimal changes were detected, while 33% had persistent chronic hepatitis, and 21% showed active chronic hepatitis. A mean Knodell index score of 2.28 was recorded; 50% of the subjects showed no fibrosis, 46% grade 1 fibrosis (fibrous portal expansion), 4% grade 2 fibrosis (bridging fibrosis), and none grade 3 fibrosis (liver cirrhosis). In the RIBA-positive group, a greater percentage of patients had active chronic hepatitis, a greater Knodell index, and increased-grade fibrosis. It can be concluded that the RIBA-3-indeterminate group is epidemiologically similar to the RIBA-3-positive series, although with a lesser prevalence of laboratory test alterations, a lower viral replication index, and more likely to have benign disease - particularly in subjects without viral replication.

Performance characteristics of the ARCHITECT anti-HCV assay

INTRODUCTION

The ARCHITECT Anti-HCV assay is a fully automated high throughput chemiluminescent microparticle immunoassay (CMIA) for the detection of antibodies to structural and nonstructural proteins of the hepatitis C virus (HCV). To further enhance the performance of this test, the assay was modified to improve the specificity for blood donor specimens.

METHODS

The specificity of the enhanced ARCHITECT Anti-HCV assay was evaluated by screening blood donor samples randomly collected from various German blood banks, as well as hospitalized patient samples derived from Germany and the US. Additionally, antibody sensitivity was determined on commercially available anti-HCV seroconversion panels and on a commercially available worldwide anti-HCV genotype performance panel.

RESULTS

Apparent specificity of the modified ARCHITECT Anti-HCV assay in a blood donor population consisting of 3811 specimens was 99.92%, compared to 99.76% for the current on-market assay. Additionally, antibody sensitivity was determined on commercially available anti-HCV seroconversion panels. Seroconversion sensitivity equivalent to or better than the current on-market product was observed by testing 33 seroconversion panels.

CONCLUSION

This study demonstrates that the modified version of the ARCHITECT Anti-HCV assay shows improved specificity for blood donor specimens compared to the current assay on market without compromising sensitivity. With the availability of the improved ARCHITECT Anti-HCV assay and the recent launch of the ARCHITECT HIV Ag/Ab Combo assay, the ARCHITECT system now offers a full hepatitis/retrovirus menu with excellent performance on a high throughput, random access, automated analyzer, ideally suited for blood screening and diagnostic applications.

Significance of the signal-to-cutoff ratios of anti-hepatitis C virus enzyme immunoassays in screening of Chinese blood donors

BACKGROUND

The correlation between signal-to-cutoff (S/CO) ratios of a second-generation hepatitis C virus (HCV) enzyme immunoassay (EIA; Abbott) and a third-generation HCV enzyme-linked immunosorbent assay (ELISA; Ortho) and confirmed HCV infection has been reported. The utility of the values for the Chinese anti-HCV EIA kits, however, has not been studied in evaluating test results in Chinese blood donors.

STUDY DESIGN AND METHODS

A total of 156 donor samples repeat reactive for anti-HCV at routine screening from five representative regions of China were retested for anti-HCV by the Ortho third-generation HCV ELISA and six Chinese EIA kits and for HCV RNA by a human immunodeficiency virus-1 and HCV assay (Procleix, Chiron Corp.). The HCV RNA-nonreactive samples were further tested for anti-HCV by a third-generation recombinant immunoblot assay RIBA (Chiron Corp.). The positive result by either nucleic acid amplification test or RIBA was interpreted as confirmed HCV infection.

RESULTS

The confirmed HCV prevalence rate in donors in five representative regions obtained in this study was 0.20 percent (77/37,900) in 2004. All seven anti-HCV EIA kits had a significant correlation between S/CO ratios and confirmed HCV infection. The threshold S/CO ratios, which predicted more than 95 percent of confirmed HCV infections for the Ortho, SABC, BGI-GBI, InTec, GWK, KHB, and WANTAI kits, were 3.8, 6.0, 7.0, 8.6, 10.0, 10.0, and 14.0, respectively.

CONCLUSIONS

Anti-HCV EIA kits commonly used in Chinese donors screening demonstrate good correlation between S/CO ratios and the confirmed infection. For the Ortho third-generation HCV ELISA, the S/CO ratio of 3.8 determined by the US Centers for Disease Control and Prevention is applicable to Chinese blood donors. The Chinese domestic EIA kits evaluated show a diverse range of threshold S/CO ratios.

Can we improve the management of blood donors with nonspecific reactivity in viral screening and confirmatory assays?

Donors with nonspecific reactivity in viral screening or confirmatory assays are problematic for blood services because of donor management issues and product loss. Considerable experience has now accumulated in the use of screening and confirmatory assays; therefore, it is timely to examine the ways in which donors with nonspecific reactivity are managed. In this review, we summarize the causes and characteristics of nonspecific reactivity in blood donors and approaches for reducing the number of nonspecific reactive results and we offer some suggestions for improving the management of these donors.