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

A new double-antigen sandwich test based on the light-initiated chemiluminescent assay for detecting anti-hepatitis C virus antibodies with high sensitivity and specificity

Objectives

The aim of this study was to evaluate the performance of a new double-antigen sandwich test that is based on the light-initiated chemiluminescent assay (LiCA®) for detecting anti-hepatitis C virus antibodies (anti-HCV) in comparison to Architect®.

Methods

Analytical characteristics and diagnostic performance were tested using seroconversion panels and large pools of clinical samples. Positive results were validated by the strip immunoblot assay (RIBA) and HCV RNA.

Results

Repeatability and within-lab imprecision of LiCA® anti-HCV were 1.31%-3.27%. The C5-C95 interval was -5.44%-5.03% away from C50. LiCA® detected seroconversion in an average of 28.9 days and showed a mean of 3.7 (p = 0.0056) days earlier than Architect®. In a pool of 239 samples with known HCV genotypes 1 to 6, both assays correctly detected all subjects. In 16,305 clinical patient sera, LiCA® detected 4 false-negative (0.25‰) and 14 false-positive (0.86‰) anti-HCV cases, while Architect® recorded 6 false-negative (0.37‰) and 138 false-positive (8.46‰) subjects, respectively. Compared to Architect®, LiCA® presented a significantly better performance in specificity (99.91% vs. 99.14%, n = 16,018, p < 0.0001), positive predictive value (95.29% vs. 67.06%, n = 419, p < 0.0001), and overall accuracy (99.89% vs. 99.12%, n = 16,305, p < 0.0001), while no significant difference in sensitivity (98.61% vs. 97.91%, n = 287, p = 0.5217) and negative predictive value (99.98% vs. 99.96%, n = 15,886, p = 0.3021) was seen. An S/Co value of 3.28 was predicted to be the threshold with a positivity ≥95% for the LiCA® anti-HCV assay.

Conclusion

LiCA® anti-HCV is a precise and fully automatic chemiluminescent assay with superior sensitivity and specificity. The assay can be used as a valuable tool to supplement the diagnosis of HCV infection.

Clinical performance of the MAGLUMI Anti-HCV (CLIA) Test for detection of hepatitis C virus antibodies

BACKGROUND

Hepatitis C virus (HCV) infection screening and diagnosis are critical to control the hepatitis C epidemic. Testing for anti-HCV antibodies (Ab) in blood samples is the first step to screen people who have been infected with the virus.

OBJECTIVES

To evaluate the performance of the MAGLUMI Anti-HCV (CLIA) Test for detection of HCV antibodies.

STUDY DESIGN

To assess the diagnostic specificity, serum samples from 5053 unselected donors and 205 blood specimens from hospitalized patients were collected. To evaluate the diagnostic sensitivity, 400 positive HCV Ab samples were collected and 30 seroconversion panels were tested. All samples that met the test criteria were tested with the MAGLUMI Anti-HCV (CLIA) Test according to manufacturer's instruction. Results of the MAGLUMI Anti-HCV (CLIA) Test were compared with the Abbott ARCHITECT anti-HCV reference test.

RESULTS

The specificity of the MAGLUMI Anti-HCV (CLIA) Test was 99.75% and 100.00% in blood donor and hospitalized patient samples, respectively. The sensitivity of the Test in HCV Ab positive samples was 100.00%. Seroconversion sensitivity was comparable between the MAGLUMI Anti-HCV (CLIA) Test and the reference assay.

CONCLUSIONS

The performance of the MAGLUMI Anti-HCV (CLIA) Test makes it suited for HCV infection diagnosis.

RT-LAMP-Based Molecular Diagnostic Set-Up for Rapid Hepatitis C Virus Testing

Hepatitis C virus (HCV) infections occur in approximately 3% of the world population. The development of an enhanced and extensive-scale screening is required to accomplish the World Health Organization's (WHO) goal of eliminating HCV as a public health problem by 2030. However, standard testing methods are time-consuming, expensive, and challenging to deploy in remote and underdeveloped areas. Therefore, a cost-effective, rapid, and accurate point-of-care (POC) diagnostic test is needed to properly manage the disease and reduce the economic burden caused by high case numbers. Herein, we present a fully automated reverse-transcription loop-mediated isothermal amplification (RT-LAMP)-based molecular diagnostic set-up for rapid HCV detection. The set-up consists of an automated disposable microfluidic chip, a small surface heater, and a reusable magnetic actuation platform. The microfluidic chip contains multiple chambers in which the plasma sample is processed. The system utilizes SYBR green dye to detect the amplification product with the naked eye. The efficiency of the microfluidic chip was tested with human plasma samples spiked with HCV virions, and the limit of detection observed was 500 virions/mL within 45 min. The entire virus detection process was executed inside a uniquely designed, inexpensive, disposable, and self-driven microfluidic chip with high sensitivity and specificity.

Society for Maternal-Fetal Medicine Consult Series #56: Hepatitis C in pregnancy-updated guidelines: Replaces Consult Number 43, November 2017

In the United States, it is estimated that 1% to 4% of pregnant women are infected with hepatitis C virus, which carries approximately a 5% risk of transmission from mother to infant. Hepatitis C virus can be transmitted to the infant in utero or during the peripartum period, and infection during pregnancy is associated with an increased risk of adverse fetal outcomes, including fetal growth restriction and low birthweight. The purpose of this document is to discuss the current evidence, provide updated recommendations regarding screening, review treatment, and address management of hepatitis C virus during pregnancy. The following are the Society for Maternal-Fetal Medicine's recommendations: (1) We suggest that third trimester assessment of fetal growth may be performed, but antenatal testing is not indicated in the setting of hepatitis C virus diagnosis alone (GRADE 2C); (2) we suggest screening for viral hepatitis in patients with a diagnosis of intrahepatic cholestasis of pregnancy at an early gestational age or with high levels of bile acids (GRADE 2C); (3) we recommend that obstetrical providers screen all pregnant patients for hepatitis C virus by testing for anti-hepatitis C virus antibodies in every pregnancy (GRADE 1B); (4) we suggest that obstetrical care providers screen hepatitis C virus-positive pregnant patients for other sexually transmitted infections (if not done previously), including human immunodeficiency virus, syphilis, gonorrhea, chlamydia, and hepatitis B virus (GRADE 2C); (5) we recommend vaccination against hepatitis A and B viruses (if not immune) for patients with hepatitis C virus (GRADE 1B); (6) we recommend that direct-acting antiviral regimens only be initiated in the setting of a clinical trial during pregnancy and that people who become pregnant while taking a direct-acting antiviral should be counseled in a shared decision-making framework about the risks and benefits of continuation (GRADE 1C); (7) we suggest that if prenatal diagnostic testing is requested, patients are counseled that data regarding the risk of vertical transmission are reassuring but limited (GRADE 2C); (8) we recommend against cesarean delivery solely for the indication of hepatitis C virus (GRADE 1B); (9) we suggest that obstetrical care providers avoid internal fetal monitors and early artificial rupture of membranes when managing labor in patients with hepatitis C virus unless necessary in the course of management (ie, when unable to trace the fetal heart rate with external monitors and the alternative is proceeding with cesarean delivery) (GRADE 2B); (10) we recommend that hepatitis C virus status not alter standard breastfeeding counseling and recommendations unless nipples are cracked or bleeding (GRADE 1A).

A study based on four immunoassays: Hepatitis C virus antibody against different antigens may have unequal contributions to detection

Background

All commercial Hepatitis C virus antibody (anti-HCV) assays use a combination of recombinant antigens to detect antibody response. Antibody responses to individual antigenic regions (core, NS3/4 and NS5) used in assays have not been investigated.

Methods

In this study, we quantified HCV viral load, tested anti-HCV with four commercial assays (Ortho-ELISA, Murex-ELISA, Architect-CMIA and Elecsys-ECLIA) in 682 plasma specimens. In antigenic region ELISA platform, microwells were coated with three antigens: core (c22-3), NS3/4 (c200) and NS5 individually. The signal-to-cutoff (S/Co) values of different assays, and antibody responses to individual antigens were compared. The specimens were divided into HCV RNA positive group, anti-HCV consistent group, and anti-HCV discrepant group.

Results

Anti-core and anti-NS3/4 were simultaneously detected in 99.2% of HCV RNA positive specimens and showed great consistency with total anti-HCV signals. Responses to the core region were more robust than those to the NS3/4 region in anti-HCV consistent group (p < 0.001). Anti-NS5 only occurred in companying with responses to the core and NS3/4 antigens, and failed to affect the final anti-HCV positive signals. In anti-HCV discrepant group, 39.0% of positive signals could not be traced back to any single antigenic region.

Conclusion

Antibody responses to the core and NS3/4 antigens were stronger, whereas responses to the NS5 antigen were the weakest, indicating that individual antigenic regions played different roles in total anti-HCV signals. This study provides an impetus for optimizing commercial anti-HCV assays.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01608-x.

Diagnostic reliability of Architect anti-HCV assay: Experience of a tertiary care hospital in India

BACKGROUND & AIMS

Anti-HCV assays are prone to false positive results. Thus, accurate detection of HCV infection is critical for the timely therapeutic management. This study ascertained the reliability of Architect anti-HCV assay (Abbott) and to estimate the agreement of this assay with Ortho HCV 3.0 ELISA Test System with Enhanced SAVe (Ortho), HCV Tri-dot (Tri-dot) and HCV-PCR in a tertiary care setting.

METHODS

A total of 78 788 consecutive sera were routinely screened for anti-HCV antibodies using Architect. All repeatedly reactive anti-HCV sera (n=1000) and anti-HCV negative sera (n=300) were tested in Ortho and in Tri-dot assays. Representative proportions of sera (n=500) with various signal-to-cut-off (S/Co) ratio were also compared with HCV-PCR.

RESULTS

When Architect was compared with Ortho, Tri-dot, and HCV-PCR, the level of agreement as assessed by kappa were .26, .16, and .27 respectively. Using Latent class analysis (LCA), we found that sensitivity and specificity were 100% and 36.1% for Architect, 93.8% and 100% for Ortho and 63.8% and 100% for Tri-dot respectively. The median S/CO ratio of Architect and Ortho anti-HCV assays were significantly different between HCV-PCR positive and negative results (P<.0001). Furthermore, Architect S/CO ratio of >8 showed higher accuracy indices in both anti-HCV assays.

CONCLUSIONS

Architect can be used as a screening assay because of its high sensitivity, high throughput, and short turnaround time. However, S/Co ratios of ≥1 to <8 in Architect necessitates HCV PCR to identify current infection and or EIA to distinguish true positivity from false biological positivity.

Diagnostic Dilemmas in Hepatitis C Virus Infection for Hemodialysis Patients

BACKGROUND

Hepatitis C virus (HCV) is a leading cause of chronic hepatitis in dialysis patients. The diagnosis of HCV infection in these patients is predominantly based on laboratory tests because of the specificity of the clinical course of the disease.

AIM

The present prospective study aimed at determining very accurately the prevalence rate of HCV infection in patients on dialysis by simultaneously testing them for anti-HCV and for HCV RNA levels.

MATERIALS AND METHODS

For the present cross-sectional longitudinal study we recruited and followed up 93 patients from St George University Hospital Hemodialysis Unit between July 2013 and December 2014. All patients were tested for anti-HCV and HCV RNA. The anti-HCV negative patients were tested for anti-HCV and HCV RNA at least twice at intervals of 6 months or more (up to 12 months). Anti-HCV antibodies were identified using a third generation ELISA assay. Commercial kits for real-time polymerase chain reaction (RT-PCR) were used to detect HCV RNA in the plasma and mononuclear cells. Aminotransferase and gammaglutamyl transpeptidase levels were studied to find if liver inflammation was present.

RESULTS

The total seroprevalence in 68 patients was 20.6% (14). Of these, 10 patients were viremic (HCV RNA+/anti-HCV+), and 4 patients (5.9%) had discordant results (anti-HCV+/HCV RNA-). Acute hepatitis was detected in one patient. Duration of dialysis in HCV viremic patients was longer than that in aviremic patients (p=0.005).

CONCLUSIONS

The present study suggests that HCV infection in dialysis patients can be diagnosed more accurately if these patients are tested using two diagnostic methods - a serological test and a biomolecular assay. Further studies with larger sample size may prove the feasibility of such approach for all dialysis patients in this country.

Threshold value of LIAISON XL anti-HCV screening assay predicting positive immunoblotting results

Some international guidelines recommend evaluating the need to confirm positive anti-hepatitis C virus (HCV) antibody screening results by means of a more specific antibody or molecular biology test on the basis of a screening threshold value (such as the sample signal/cut-off ratio) that can predict the positivity of additional antibody testing in at least 95% of cases. The aim of this study was to determine the threshold value of the DiaSorin LIAISON XL chemiluminescence test. Two hundred and twenty-eight routine laboratory samples that were chemiluminescence positive for anti-HCV antibodies but had different signal/cut-off ratios were assayed using immunoblotting, which indicated that 155 (68.0%) were positive, 40 (17.5%) were negative, and 33 (14.5%) were indeterminate. When the samples were divided on the basis of their signal/cut-off ratios, 95.5% of the samples with a ratio of ≥3.5 were positive as against 74.1% of the positive or indeterminate samples with a ratio of <3.5. Statistical analysis using Youden's index and a receiver operating characteristic curve showed that the optimum cut-off value was 3.65. These findings indicate that, when using the LIAISON XL system for anti-HCV antibody screening, a signal/cut-off ratio of ≥3.65 makes further confirmatory tests unnecessary.

Systematic review of the accuracy of antibody tests used to screen asymptomatic adults for hepatitis C infection

BACKGROUND

Several expert groups, including the United States Preventive Services Task Force and the Canadian Task Force on Preventive Health Care, have recently examined or are currently examining whether primary care physicians should screen asymptomatic adults for hepatitis C virus (HCV) infection. To inform decision-making on HCV screening, we performed a systematic review of the accuracy of antibody tests compared with other immunoassays and RNA detection for screening asymptomatic adults for HCV infection in Canada.

METHODS

MEDLINE and Embase databases were searched from 1990 to 2016; resulting citations were uploaded into DistillerSR and independently screened by 2 reviewers. Original research studies, systematic reviews and meta-analyses were eligible for inclusion. At least 80% of the study population had to be asymptomatic, nonpregnant, treatment-naïve adults with unknown liver enzyme values and unknown HCV status. Risk of bias was assessed with the use of the Quality Assessment of Diagnostic Accuracy Studies version 2 (QUADAS-2) tool; the quality of the body of evidence was assessed by means of GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology.

RESULTS

Of 1537 articles identified, 81 underwent full-text review, and 9 studies met the inclusion criteria. Compared with RNA detection, the sensitivity of the third-generation enzyme-linked immunosorbent assay was variable (61.0%-81.8%), and its specificity was high (97.5%-99.7%). As expected, there were more false-positive results when comparing antibody tests to RNA detection than to other immunoassays. Our GRADE assessment suggested that there was a high concern for risk of bias, particularly verification bias, and substantial inconsistency between studies in terms of their design.

INTERPRETATION

More research is needed to better characterize the accuracy of antibody tests used to screen for HCV infection in the general population. Jurisdictions that recently adopted birth cohort screening for HCV infection are encouraged to evaluate and report on the accuracy of HCV screening tests and screening benefits and harms. PROSPERO registration: no. CRD42016039710.

Syphilis testing algorithms: A review

The methods and strategies used to screen for syphilis and to confirm initially reactive results can vary significantly across clinical laboratories. While the performance characteristics of these different approaches have been evaluated by multiple studies, there is not, as of yet, a single, universally recommended algorithm for syphilis testing. To clarify the currently available options for syphilis testing, this update will summarize the clinical challenges to diagnosis, review the specific performance characteristics of treponemal and non-treponemal tests, and finally, summarize select studies published over the past decade which have evaluated these approaches. Specifically, this review will discuss the traditional and reverse sequence syphilis screening algorithms commonly used in the United States, alongside a discussion of the European Centre for Disease Prevention and Control syphilis algorithm. Ultimately, in the United States, the decision of which algorithm to use is largely dependent on laboratory resources, the local incidence of syphilis and patient demographics.

Role of signal-to-cut-off ratios of anti-hepatitis C virus antibody by enzyme immunoassays along with ID-NAT for screening of whole blood donors in India

Background:

The use of elevated signal-to-cut off ratios (S/CO) as an alternate to further supplemental testing (i.e., RIBA) has been included in the guidelines provided by the Centres for Disease Control and Prevention for HCV diagnostic purposes since 2003. With availability of screening by NAT and non availability of RIBA, further confirmation of HCV infection has been possible at the molecular level (RNA).

Aims:

To study the role of S/CO ratios of anti hepatitis C virus antibody detection by enzyme immunoassays (EIA) along with ID-NAT for screening of whole blood donors.

Methods:

In this study we reviewed the donor screening status for anti HCV from January 2013 to May 2014. All the donations were screened for anti HCV with fourth generation ELISA (BioRad Monolisa Ag-Ab Ultra) as well as with ID NAT (Procleix Ultrio). The S/CO ratio of all the anti-HCV reactive samples were analysed for their presence of HCV RNA.

Results:

On screening 21,115 donors for HCV, 83 donors (0.39%) were found reactive on pilot tube and repeat plasma bag testing (S/Co ratio ≥1) by ELISA. 41 donors were HCV RNA reactive with ID-NAT. 4 samples out of 41 were NAT yields and 37 were concordant reactive with ELISA. The S/Co ratio of anti-HCV reactive samples ranged from 0.9-11.1 [mean = 5.1; SD ± 2.9] whereas S/Co ratio of anti HCV and NAT reactive samples (concordant positives) ranged from 4.1-11.1 [mean 7.3]. In our analysis we found that S/CO ratio of 4 showed positive predictive value (PPV) and sensitivity of 100%.

Summary/Conclusions:

Our study showed that S/CO of 4 for anti HCV on ELISA would have maximum positive predictive value of having donor with HCV RNA. S/CO ratio of 4 is very close to 3.8 which was the CDC guideline. The presence of anti-HCV does not distinguish between current or past infections but a confirmed anti-HCV-positive result indicates the need for counseling and medical evaluation for HCV infection.

Is Anti-Hepatitis C Virus Antibody Level an Appropriate Marker to Preclude the Need for Supplemental Testing

OBJECTIVES

In the present study, we aimed to determine whether signal-to-cutoff (S/Co) ratios of reactive anti-HCV samples could be used as a basis for avoiding the need for supplemental testing in our study population.

METHODS

We analyzed 901 anti-HCV-positive sera from 8 institutions in China. The Ortho VITROS anti-HCV assay and Monolisa Plus anti-HCV version 2 were used as screening assays to detect anti-HCV antibodies. Recombinant immunoblot assay (RIBA) and quantitative tests for HCV RNA were performed to validate confirmed HCV infection status.

RESULTS

Receiver operating characteristic curve analyses demonstrated that 41.5% (114/275) of true-positive samples with S/Co ratios ≤3.0 would be missed and the negative predictive value was 63.9 and 87.06%, using real-time polymerase chain reaction (RT-PCR) and RIBA as supplemental testing, respectively. 29.8% (90/302) of those who tested positive by RIBA samples were missed when only RT-PCR was used as supplemental testing.

CONCLUSIONS

We determined that very low anti-HCV levels (S/Co ≤3.0), as determined by chemiluminescence immunoassay, was not an appropriate marker to preclude the need for supplemental testing in our study population. A screening strategy employing a secondary HCV antibody assay using different HCV antigens from the first assay as the supplemental testing method should be studied further. The immunoblot assay, as a supplemental testing method, is still necessary.

Comparison of Rapid Point-of-Care Tests for Detection of Antibodies to Hepatitis C Virus

OraSure had the highest sensitivity at 92.7% followed closely by Chembio's three blood tests. False results were associated with HIV, and hepatitis B core antibody. The OraSure and Chembio blood tests have good performance characteristics.

Background. Hepatitis C is one of the most prevalent blood-borne diseases in the United States. Despite the benefits of early screening, among 3.2 million Americans who are infected with hepatitis C virus (HCV), 50%–70% are unaware of their infection status.

Methods. Data were collected between 2011 and 2014, from 1048 clients who were in the following groups: (1) injection drug users, (2) women at sexual risk, (3) gay and bisexual men, and (4) transgender individuals. The sensitivity and specificity of point-of-care tests included (1) the MedMira rapid human immunodeficiency virus (HIV)/HCV antibody test, (2) MedMira hepatitis B (HBV)/HIV/HCV antibody test, (3) Chembio HCV Screen Assay used with both whole blood and (4) oral specimens, (5) Chembio HIV-HCV Assay also used with both whole blood and (6) oral specimens, (7) Chembio HIV-HCV-Syphilis Assay, and (8) OraSure HCV Rapid Antibody Test used with whole blood. The gold standard for the HCV tests were HCV enzyme immunoassay (EIA) 2.0.

Results. OraSure had the highest sensitivity at 92.7% (95% confidence interval [CI] = 88.8%–96.5%) followed closely by Chembio's 3 blood tests at 92.1% (95% CI = 87.7%–96.4%), 91.5% (95% CI = 87.2%–95.7%), and 92.3% (95% CI = 88.4%–96.2%). The sensitivities of MedMira HIV/HCV and MedMira HIV/HCV/HBV tests were the lowest, at 79.1% (95% CI = 72.6%–85.5%), and 81.5% (95% CI = 75.2%–87.8%), respectively. Specificity for the OraSure was 99.8% (95% CI = 99.4%–100%); specificity for the Chembio blood tests was 99.2% (95% CI = 98.6%–99.9%), 99.4% (95% CI = 98.8%–99.9%), and 99.3% (95% CI = 98.8%–99.9%); and specificity for the MedMira was100% and 100%. False-negative results were associated with HIV and hepatitis B core antibody serostatus.

Conclusions. The OraSure and Chembio blood tests (including those multiplexed with HIV and syphilis) appear to good performance characteristics. This study has identified potential limitations of rapid testing in those testing positive for HIV and HBcAb. There should be discussion of updates to the 2013 CDC guidance.

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.

Prevalence of HIV and HCV infections in two populations of Malian women and serological assays performances

AIM

To estimate the prevalence of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections in women in Mali and to evaluate the performance of serological assays.

METHODS

Two prospective studies were conducted in 2009 and 2010 in Mali. They concerned first, 1000 pregnant women attending six reference health centers in Bamako (Malian capital) between May 26 and June 16, 2009; and secondly, 231 women over 50 years who consulted general practitioners of two hospitals in Bamako between October 25 and December 24, 2010. Blood samples were collected and kept frozen in good condition before analysis. All samples depicted as positive using HIV/HCV enzyme immuno-assay screening assays were submitted to confirmation analysis. Molecular markers of HCV were characterized.

RESULTS

The seroprevalence of HIV and HCV in the population of pregnant women was 4.1% and 0.2% respectively. Among older women the seroprevalence was higher and similar for HIV and HCV (6.1% vs 6.5%). The anti-HIV prevalence was not different in young and older women (4.1% vs 6.1%). In contrast, the anti-HCV prevalence was higher in older compared to younger women (6.5% vs 0.2%, P < 0.01). Of 2 pregnant women who were HCV seropositive, only one was polymerase chain reaction (PCR) reactive and infected by genotype 2, with a viral load of 1600 IU/mL. Regarding older women who were HCV seropositive, 13 out of 15 were PCR reactive, infected by genotype 1 or 2. Globally HCV genotype 2 was predominant. The positive predictive value (PPV) measured with VIKIA HIV test in young women was 100% therefore significantly higher than the 87.5% measured in older women (P < 0.05). Conversely, the PPV measured with Monolisa HCV assay in older women was 88.2% and higher than the 14.3% measured in younger women (P < 0.01).

CONCLUSION

Whereas HIV prevalence was similar in both subpopulations HCV was more frequent among older women (P < 0.01). The PPV of screening assays varied with the age of the subjects.

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%.