Performance of second- and third-generation RIBAs for confirmation of third-generation HCV EIA-reactive blood donations. Retrovirus Epidemiology Donor Study

The National Heart, Lung, and Blood Institute retrovirus epidemiology donor studies (Retrovirus Epidemiology Donor Study and Retrovirus Epidemiology Donor Study-II): twenty years of research to advance blood product safety and availability

The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989 to 2001, and the REDS-II, conducted from 2004 to 2012, were National Heart, Lung, and Blood Institute-funded, multicenter programs focused on improving blood safety and availability in the United States. The REDS-II also included international study sites in Brazil and China. The 3 major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as xenotropic murine leukemia virus-related virus. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of human immunodeficiency virus, human T-lymphotropic virus 1/2, hepatitis C virus, hepatitis B virus, West Nile virus, cytomegalovirus, human herpesvirus 8, parvovirus B19, malaria, Creutzfeldt-Jakob disease, influenza, and Trypanosoma cruzi infections. Other analyses have characterized blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors' perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, 2 large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these 2 REDS programs. In 2011, a new 7-year program, the Recipient Epidemiology and Donor Evaluation Study-III, was launched. The Recipient Epidemiology and Donor Evaluation Study-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting and adds a third country, South Africa, to the international program.

A 25-year study of the clinical and histologic outcomes of hepatitis C virus infection and its modes of transmission in a cohort of initially asymptomatic blood donors

BACKGROUND

A total of 738 volunteer blood donors who were positive for anti-hepatitis C virus (HCV) were assessed for risk factors and outcomes for up to 15 years within the study and up to 54 years from the estimated onset of infection.

METHODS

A third-generation recombinant immunoblot assay (RIBA) was performed to distinguish true from false anti-HCV reactivity. Findings of HCV polymerase chain reaction classified subjects as having chronic HCV infection or as having recovered. Liver biopsy specimens were staged by Ishak fibrosis score and graded by histologic activity index.

RESULTS

Of 738 anti-HCV-positive subjects, 469 (64%) had positive RIBA results, 217 (29%) had negative results, and 52 (7%) had indeterminate results. Primary independent risk factors were injection drug use (odds ratio [OR], 35.0; P < .0001), blood transfusion (OR, 9.9; P < .0001), and intranasal cocaine use, including 79 "snorters" who repeatedly denied injection drug use or blood transfusion (OR, 8.5; P < .0001). Classification and regression tree and random forest analyses confirmed these risk factors. A total of 384 RIBA-positive donors (82%) were HCV RNA positive; of these, liver biopsy specimens from 185 (48%) showed no fibrosis in 33%, mild fibrosis in 52%, bridging fibrosis in 12%, and cirrhosis in 2% a mean duration of 25 years after infection. Analysis of 63 repeat biopsy specimens showed that 8% progressed ≥2 Ishak stages over 5 years (mean progression, 0.06 Ishak stages/year).

CONCLUSIONS

Injection drug use and blood transfusion before 1990 are dominant risk factors for HCV acquisition; intranasal cocaine use may be a surreptitious route of parenteral spread. After a mean of 25 years of HCV infection, histologic outcomes were relatively mild: 85% had no or mild fibrosis, and only 2% had cirrhosis. Nearly one-fifth spontaneously recovered.

Viruses and arthritis: new challenges in diagnosis, therapy, and immunization

BACKGROUND

Although many viruses produce musculoskeletal symptoms during an acute infection, a long-term inflammatory arthritis remains an unusual consequence. When evaluating arthritis in a patient with a chronic or latent viral infection, serologic testing and therapeutic options are significantly altered.

RESULTS

The example of hepatitis C reveals how chronic infection can complicate the diagnosis of rheumatoid arthritis. Determination of rheumatoid factor is of limited utility, whereas the anticyclic citrullinated peptide has become a new test with improved specificity. Therapeutic options are severely constrained because of potential hepatotoxicity of oral agents such as methotrexate and leflunomide. Antitumor necrosis factor alpha biologics have demonstrated initial safety in the setting of hepatitis C virus but may be associated with reactivation of hepatitis B virus. Biologics such as abatacept and rituximab have been inadequately studied in this population to date. Prevention of viral infections by influenza and herpes zoster vaccines in rheumatoid arthritis patients needs improved administration rates and careful planning to maximize efficacy.

CONCLUSIONS

Chronic viral infections complicate the diagnosis and therapy of inflammatory arthritis. The antitumor necrosis factor alpha biologics have become important therapeutic options for patients with hepatitis C. Vaccination against influenza and herpes zoster are underused in health maintenance of arthritis patients.

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.

Immunoblot assay using recombinant antigens as a supplemental test to confirm the presence of antibodies to Trypanosoma cruzi

The diagnosis of chronic Chagas' disease is generally made by detecting antibodies to Trypanosoma cruzi. Most conventional serological tests are based on lysates of whole parasites or semipurified antigen fractions from T. cruzi epimastigotes grown in culture. The occurrence of inconclusive and false-positive results has been a persistent problem with the conventional assays, and there is no universally accepted gold standard for confirmation of positive test results. We describe here an immunoblot assay for detecting antibodies to T. cruzi in which four chimeric recombinant antigens (rAgs), designated FP3, FP6, FP10, and TcF, are used as target antigens. Each of these rAgs is composed of several antigenically distinct regions and includes repetitive as well as nonrepetitive sequences. Each rAg is coated as a discrete line on a nitrocellulose strip. Assay sensitivity was assessed by testing 345 specimens known to be positive for antibodies to T. cruzi. All 345 of these samples showed two to four reactive test bands in addition to the three on-board control bands that are on each strip. Assay specificity was determined by testing 500 specimens from random U.S. blood donors, all of which gave negative results. Based on the results obtained in this study, we propose the following scheme for interpretation of test results: (i) no bands or a single test band = a negative result; (ii) two or more test bands with at least one band showing intensity of 1+ or higher = a positive result; and (iii) multiple faint test bands (+/-) = indeterminate result. Based on this scheme, the prototype immunoblot assay showed sensitivity of 100% (n = 345) and specificity of 100% (n = 500). Additionally, all 269 potentially cross-reacting and T. cruzi antibody-negative specimens tested negative in our immunoblot assay. The rAg-based immunoblot assay has potential as a supplemental test for confirming the presence of antibodies to T. cruzi in blood specimens and for identifying false-positive results obtained with other assays.

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.

Usefulness of the phage display technology for the identification of a hepatitis C virus NS4A epitope recognized early in the course of the disease

A dodecapeptide phage-displayed library was screened with the mouse monoclonal antibody (mAb) 2E3C2 which competed with human antibodies for the binding to the HCV c100 recombinant protein. Four mimotopes shared a consensus motif with the HCV 1701-1707 sequence corresponding to the carboxyl-terminal domain of the non-structural protein NS4A. However, these mimotopes reacted with 2E3C2 only, whereas the corresponding NS4 epitope defined at the sequence 1698-1709 and displayed on phage was recognized by both 2E3C2 and sera from HCV infected patients. Using the Spot method of multiple peptide synthesis and alanine replacement analysis, the respective reactivities of mAb 2E3C2 and anti-NS4A human antibodies against NS4 were shown to be directed against two slightly different overlapping minimal linear sequences and to involve different critical residues. The phage clone displaying the NS4 epitope was used to study the specific recognition of this epitope by different individual HCV positive sera as well as by two seroconversion panels of sera from HCV infected patients. Compared with the detection by RIBA of the different HCV antigens and c100 particularly, these results indicated that the antibodies directed against the NS4 (1698-1709) epitope were produced early during the course of the disease and decreased later.

Distribution of hepatitis C virus genotypes among blood donors from mid-west region of Brazil

In order to investigate the hepatitis C virus (HCV) genotypes in mid-west region of Brazil, 250 anti-HCV positive blood donors were studied. Among them, the anti-HCV serological status was confirmed in 205 (82%). HCV RNA was detected in 165 samples, which were genotyped. HCV types 1, 2 and 3 were found in 67.9%, 3% and 29.1% of the donors, respectively. In Goiás state, subtype 1a (50%) was the most prevalent, followed by subtypes 3a (30.9%) and 1b (16.7%). In Mato Grosso state, subtype 1a was also predominant (41%), followed by subtypes 1b (29.5%) and 3a (25%). In Mato Grosso do Sul state, subtypes 1a and 1b were detected equally (36.8%), followed by 3a (21.1%). Subtype 2b was rare (2.4%, 4.5% and 5.3%, respectively). In Distrito Federal, subtype 3a (39%) was more frequent than 1a (31.7%) and the remaining (29.3%) belonged to subtype 1b.

Safety of the blood supply in Latin America

Appropriate selection of donors, use of sensitive screening tests, and the application of a mandatory quality assurance system are essential to maintain the safety of the blood supply. Laws, decrees, norms, and/or regulations covering most of these aspects of blood transfusion exist in 16 of the 17 countries in Latin America that are the subject of this review. In 17 countries, there is an information system that, although still incomplete (there are no official reports on adverse events and incidents), allows us to establish progress made on the status of the blood supply since 1993. Most advances originated in increased screening coverage for infectious diseases and better quality assurance. However, in 2001 to 2002, tainted blood may have caused infections in 12 of the 17 countries; no country reached the number of donors considered adequate, i.e., 5% of the population, to avoid blood shortages, or decreased significantly the number of blood banks, although larger blood banks are more efficient and take advantage of economies of scale. In those years, paid donors still existed in four countries and replacement donors made up >75% of the blood donors in another eight countries. In addition, countries did not report the number of voluntary donors who were repeat donors, i.e., the healthiest category. In spite of progress made, more improvements are needed.

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

BACKGROUND

One of the problems associated with the use of anti-HCV immunoblot assays is the interpretation of indeterminate results without detectable HCV RNA. The purpose of this study was to examine the significance of third-generation RIBA (RIBA-3)-indeterminate, RNA-negative results in voluntary blood donors.

STUDY DESIGN AND METHODS

Since June 2000 all Australian Red Cross Blood Service testing sites have used an anti-HCV sequential immunoassay testing strategy whereby donors who are reactive on the primary screening immunoassay are tested on a secondary immunoassay and if reactive on both assays, further tested by immunoblot. From the four testing sites that use RIBA-3, the result profiles of donors who were RIBA-3-indeterminate, HCV RNA-negative were analyzed.

RESULTS

From 2,661,786 donations screened for anti-HCV during the study period, 102 RIBA-3-indeterminate, RNA-negative donors were identified, most of whom were reactive to either c33p (69.6%) or c22p (27.5%). The RIBA-3-indeterminate, RNA-negative donors showed a significantly higher screening immunoassay signal strength to assay cutoff (S/CO) distribution than those with biologic false-reactive (BFR) results (1.853 vs. 1.524, p < 0.05) but a significantly lower distribution than RIBA-3-positive, RNA-negative (1.853 vs. 4.546, p < 0.05) or RNA-positive (1.853 vs. 6.467, p < 0.05) donors. The RIBA-3-indeterminate, RNA-negative donors showed a similar distribution of c33c and c22p band intensities compared with RIBA-3-positive, RNA-negative donors but significantly lower distribution of band strengths compared to the RIBA-3-positive, RNA-positive group. Compared to the indeterminate donors with previous anti-HCV-negative or BFR results, the indeterminate donors not previously screened for anti-HCV showed higher immunoassay S/CO ratio distributions, a higher proportion with c22p reactivity (16.2% vs. 36.7%), and higher frequency of risk factors (46.4% vs. 75.0%).

CONCLUSIONS

Our analysis suggests that a combination of indicators can be used to help clarify RIBA-3-indeterminate, RNA-negative results. Specifically, donors with high S/CO ratios on a screening immunoassay, RIBA-3 reactivity to c22p or c33c with band intensity of 2+ or greater, without a previous history of negative or BFR donations and with an identifiable risk factor, have a high probability of representing true anti-HCV rather than nonspecific reactivity.

Low prevalence of HCV, HIV, and HTLV-I/II infection markers in northwestern Greece: results of a 3-year prospective donor study (1995-1997)

Background: The risk of infection with transfusion-transmitted viruses has been reduced remarkably. A zero-risk blood supply, however, remains a popular goal. A 3-year prospective donor study was conducted in the Epirus region of Greece to determine the prevalence of human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), hepatitis B virus, and hepatitis C virus (HCV). Herein, we report the prevalence of HIV, HTLV, and HCV infection markers in this area. Methodology: Between January 1, 1995 and December 31, 1997, 6696 donors were investigated for the presence of anti-HIV, anti-HTLV, and anti-HCV antibodies using standard enzyme immunoassays (EIA). Every sample with anti-HCV reactivity by third-generation EIA was further investigated using a third-generation recombinant immunoblot assay (RIBA 3.0) and HCV-RNA by a combination of polymerase chain reaction (PCR) and DNA EIA. Results: None of the donors tested positive for anti-HIV or anti-HTLV antibodies. In contrast, anti-HCV was detected in 41 donors (0.61%). Using a RIBA 3.0 test, eight donors tested positive and eight had indeterminate results, while 25 tested negative. Seven of the eight donors with both EIA and RIBA 3.0 reactivity had increased levels of aminotransferases and detectable serum HCV-RNA. The remaining 34 donors had repeatedly normal aminotransferases and three times negative HCV-RNA. Liver biopsy was performed in anti-HCV/HCV-RNA-positive donors (7/41). The lesions were compatible with chronic hepatitis C in all of them. Conclusion: A zero prevalence of HIV and HTLV infection markers was found. Although the number of annual donations in this study was relatively low, the negative data for HIV and HTLV clearly indicate that rates of these infections are low in our region and that infected donors will be seen infrequently. HCV infection in blood donors remains very low in our region and is similar to the data reported in other industrialized countries. In fact, the prevalence of definite HCV infection seems to be very low (7/6696; 0.1%). However, a significant proportion of anti-HCV-reactive donors by third-generation EIA (33/41) had indeterminate or negative results by the RIBA 3.0. The latter donors were repeatedly negative for HCV-RNA. This finding may indicate that some donors tested false-positive for anti-HCV, although the possibility of true HCV infection contracted in the distant past cannot be excluded. In our opinion, close attention to mandatory principles of transfusion medicine, along with the screening of plasma donors using nucleic acid amplification technology, are the only methods that can further ensure the safety of our blood supply.

Comparative yield of HCV RNA testing in blood donors screened by 2.0 versus 3.0 antibody assays

BACKGROUND

Two HCV antibody tests (EIA 2.0 [EIA2], Abbott; and the Version 3.0 ELISA [EIA3], Ortho) are currently licensed for screening of US blood donors. Testing of donors for HCV RNA allows comparison of the sensitivities of the two antibody-screening assays.

STUDY DESIGN AND METHODS

All allogeneic blood donations at 13 US test sites were screened for HCV RNA by testing plasma minipools using an investigational assay (COBAS AmpliScreen HCV test, v2.0, Roche Molecular Systems). Some sites screened for HCV antibody by EIA2 and some used EIA3. The frequency of RNA-positive and antibody-negative (RNA-pos and Ab-neg) donations among donors screened by each antibody assay was compared. Antibody appearance was assessed in a donor follow-up study.

RESULTS

A total of 5.51 x 10(6) donations were screened for HCV RNA. Of these, 2.27 million were screened for antibody by EIA2, and 3.24 million by EIA3. Twenty-three donations were HCV RNA-pos and Ab-neg. The frequency of RNA-pos and Ab-neg donations was higher among donations screened by EIA2 (1 in 134,000), compared to those screened by EIA3 (1 in 540,000) (p = 0.001). Of the 17 RNA-pos and Ab-neg donations identified by test sites that used EIA2, 14 were retested by EIA3 and 10 (71%) were reactive. Most RNA-pos and Ab-neg donors appear to be in the process of seroconversion. Donors that were initially EIA2-negative and EIA3-reactive showed a more prolonged pattern of seroconversion compared to those that were initially nonreactive by both antibody assays. Four donors were EIA2-negative, EIA3-reactive, and RIBA-indeterminate (c33c) for at least 90 days, 1 for more than 317 days.

CONCLUSION

EIA3 would have detected the majority of RNA-positive donations missed by EIA2. Some RNA-positive donors are EIA2-negative and EIA3-reactive for a prolonged period of time.

Anti-HCV confirmatory testing of voluntary blood donors: comparison of the sensitivity of two immunoblot assays

BACKGROUND

In this study, the sensitivity of two commercially available anti-HCV immunoblot assays (HCV Western blot (Wellcozyme] and RIBA 3.0 SIA [RIBA-3, Chiron]) was compared in a voluntary blood donor population.

STUDY DESIGN AND METHODS

Four groups of donor samples were retrospectively tested in this study. Groups 1 and 2 were donor samples that gave positive or indeterminate band patterns, respectively, when originally tested on the HCV Western blot between 1994 and 1998. These samples were tested on the RIBA 3.0. Donor samples in Groups 3 and 4 were originally tested on RIBA-3 during 1998 and 1999 and gave positive or indeterminate blot results, respectively. In this study these two groups were tested on the HCV Western blot. Samples with discrepant results on the two immunoblot assays were selected for genotyping or serotyping.

RESULTS

The two immunoblots showed similar sensitivity to the core and NS5 proteins. However, of 35 samples positive on Western blot or RIBA-3, the Western blot failed to detect NS4 in 14 samples compared with only 5 for RIBA-3. As well, the Western blot failed to detect NS3 in 6 samples compared to 2 for RIBA-3. Five (27.8%) of 18 samples that were Western blot indeterminate due to core reactivity showed an additional NS3 band on RIBA-3. Of the samples with additional NS3 and/or NS4 reactivity on RIBA-3 that were genotyped or serotyped, all were HCV type 3.

CONCLUSIONS

Western blot and RIBA-3 showed similar sensitivity to the HCV core and NS5 proteins. However, RIBA-3 showed greater sensitivity to both NS3 and NS4 compared to the Western blot. The reduced sensitivity of the Western blot to the NS3 and NS4 proteins was observed with HCV type 3 samples.