Confirmation of hepatitis C virus positive blood donors by immunoblotting and polymerase chain reaction

High rate of chronicity in HCV infection determined by antibody confirmatory assay and PCR in 4110 patients during long-term follow-up

BACKGROUND

It is still unclear how many patients with hepatitis C virus (HCV) antibodies have viremia and hence are infectious.

OBJECTIVES

To determine the chronicity of HCV infection by correlation of HCV antibodies with presence of viremia in long-term follow-up.

STUDY DESIGN

In a longitudinal study sera of 4110 patients were analyzed with second generation HCV-enzyme immunoassay (EIA) and polymerase chain reaction (PCR). Only those patients were included in this study in whom sequential serum samples over a period of 2 years were available. To avoid preanalytical and analytical failures, we used a transport solution to prevent RNA degradation and a four-antigen recombinant immunoblot assay, established in our laboratory, for confirmation of antibody reactivity.

RESULTS

Of 2815 patients with confirmed HCV antibodies 2784 (98.9%) were also positive in HCV-PCR assay. False reactive EIA results were detected in 177 (13.7%) individuals as shown by confirmatory assay and PCR. Only one patient (0.04%) spontaneously lost detectable HCV viremia and subsequently HCV-specific antibodies.

CONCLUSIONS

Our study clearly demonstrates that presence of confirmed HCV-specific antibodies correlates significantly (98.9%; P < 0.001) with HCV viremia, and that spontaneous loss of viremia is a very rare event in HCV infection. We also found that elimination of HCV infection is not sufficiently predicted by the loss of detectable viremia in PCR, but can be concluded from the disappearance of virus-specific antibodies.

Study of the dynamics of neutralization escape mutants in a chimpanzee naturally infected with the simian immunodeficiency virus SIVcpz-ant

Here we report on the use of spectral map analysis of time-paired sequential neutralization data of 11 serum samples of a chimpanzee naturally infected with a simian immunodeficiency virus (SIVcpz-ant) and 8 primary consecutive SIVcpz-ant isolates, taken at about 4-month intervals. The analysis reveals the existence of three SIVcpz-ant isolate and serum neutralization clusters. Each cluster groups virus isolates and/or sera based on similarities of their neutralization spectra. On average, neutralization escape mutants emerged after 15 months and mounted a neutralization response approximately 8 months later. The entire gp160 regions of eight consecutive isolates were sequenced and analyzed by a new statistical method called polygram, which allowed the deduction of amino acid sequence motifs of gp160 which were specific for SIVcpz-ant isolates belonging to the same isolate neutralization clusters. Changes in specific amino acid quadruplets in V1, V2, C3, V4, V5, and CD4 domains of gp120 and gp40 were seen to correlate with the neutralization clusters with most of the specific changes occurring in the V4 region. This method of analysis may facilitate an understanding of the study of the dynamic interplay between human immunodeficiency virus (HIV) and host neutralization responses as well as providing possible insights into mechanisms of persistence of HIV-1-related lentiviruses in their natural hosts.

Cost-effectiveness of screening blood donors for hepatitis C and non-A, non-B, non-C hepatitis. The EATHIS Eco Research Group. European Acute Transfusion Hepatitis Interferon Study

The current approach to screening for hepatitis C and non-A, non-B, non-C hepatitis in French blood transfusion centers involves a combination of a transaminase assay and tests for antibodies to hepatitis B core antigen (anti-HBc) and antibodies to hepatitis C virus (anti-HCV). A decision-analysis model was used to assess the cost-effectiveness ratio of this approach compared to the former approach, which included only transaminase and anti-HBc screening. Cost data were collected by a questionnaire sent to 26 centers throughout France. The average costs of diagnostic kits, equipment, staff, and administration were calculated. Estimates of prevalence and sensitivity values came from the medical literature. The cost-effectiveness ratio was expressed in French francs per infected donor detected. A sensitivity analysis of the variables in the model was performed to estimate the validity of the cost-effectiveness ratio. For 100,000 donations the incremental cost of the current approach reached FrF 2,566,111 (about US $500,000), with a marginal effectiveness of 180 donations detected. The sensitivity analysis showed the effect of prevalence on the incremental cost-effectiveness ratio. Transfusion centers may change their screening approach in areas of high or low prevalence of hepatitis C in France.

Existing problems in the testing for infectious diseases

Current methods for testing donated blood for presence of infectious viral agents in the USA differ from those used in other countries because of the USA Food and Drug Administration's (FDA) control which inhibits rapid introduction of testing methods or improvements. Delays in FDA approval may occur because of concerns about methodology or the state of knowledge about the disease it is intended to detect as well as due to variability between manufacturers. Despite strict FDA control, testing problems continue to occur in the USA. No approved method detects infectious agents during the "window period," and variations in detection, i.e., false positives and false negatives (even with confirmatory testing), continue to occur. The effect of physical and chemical changes (e.g., various anticoagulants) on samples has not been thoroughly evaluated. Test performance problems include lapses in sample identification, failure to use routine laboratory controls, improper calculation and reporting of results, improper acceptance of test runs and failure to properly detect and retest samples when carryover from very reactive samples occurs. For these reasons, transfusion-related disease transmission continues to occur. The current USA emphasis on good manufacturing practices should provide continuous improvements.

Anti-HCV related to HCV PCR and risk factors analysis in a blood donor population of central Brazil

Data concerning HCV infection in Central Brazil are rare. Upon testing 2,350 voluntary blood donors from this region, we found anti-HCV prevalence rates of 2.2% by a second generation ELISA and 1.4% after confirmation by a line immunoassay. Antibodies against core, NS4, and NS5 antigens of HCV were detected in 81.8%, 72.7%, and 57.5%, respectively, of the positive samples in the line immunoassay. HCV viremia was present in 76.6% of the anti-HCV-positive blood donors. A relation was observed between PCR positivity and serum reactivity in recognizing different HCV antigens in the line immunoassay. The majority of the positive donors had history of previous parenteral exposure. While the combination of ALT > 50 IU/l and anti-HBc positivity do not appear to be good surrogate markers for HCV infection, the use of both ALT anti-HCV tests is indicated in the screening of Brazilian blood donors.

Detection of human immunodeficiency virus type 1 (HIV-1) in heel prick blood on filter paper from children born to HIV-1-seropositive mothers

The human immunodeficiency virus type 1 (HIV-1) DNA PCR results of 94 dried blood spot (DBS) samples on filter paper and corresponding venous blood in EDTA obtained from infants born to HIV-1-seropositive mothers were compared. In addition, the results of HIV-1 DNA PCR on DBS and the HIV-1 RNA PCR from plasma of 70 paired samples were compared. A 100% specificity and a 95% sensitivity for HIV-1 DNA PCR on DBS compared with results for venous blood were observed for the 94 paired samples. The results of the DBS HIV-1 DNA PCR and HIV-1 RNA PCR of 70 corresponding plasma samples correlated perfectly (100%). The DBS HIV-1 DNA PCR method proved reliable for HIV-1 detection.

Hepatitis C: progress and problems

The hepatitis C virus (HCV), a single-stranded RNA virus, is the major cause of posttransfusion hepatitis. HCV isolates differ in nucleotide and amino acid sequences. Nucleotide changes are concentrated in hypervariable regions and may be related to immune selection. In most immunocompetent persons, HCV infection is diagnosed serologically, using antigens from conserved regions. Amplification of RNA may be necessary to detect infection in immunosuppressed patients. Transmission by known parenteral routes is frequent; other means of spread are less common and may represent inapparent, percutaneous dissemination. Infection can lead to classical acute hepatitis, but most infected persons have no history of acute disease. Once infected, most individuals apparently remain carriers of the virus, with varying degrees of hepatocyte damage and fibrosis ensuing. Chronic hepatitis may lead to cirrhosis and hepatocellular carcinoma. However, disease progression varies widely, from less than 2 years to cirrhosis in some patients to more than 30 years with only chronic hepatitis in others. Determinants important in deciding outcome are unknown. Alpha interferon, which results in sustained remission in selected patients, is the only available therapy. Long-term benefits from such therapy have not been demonstrated. Prevention of HCV infection by vaccination is likely to be challenging if ongoing viral mutation results in escape from neutralization and clearance.

Analysing the sequence diversity of the 5' NC-region of HCV-isolates found in southern Germany

In this study we compared the nucleotide sequence of the 5' NC-region of the HCV genome isolated from seven patients and two blood donors from Southern Germany. We could identify two very distinct groups of isolates: the first very similar to the HCV prototype sequence (HCV1) with homology ranging from 99.5% to 98.7%; the second showing 91.7% homology to the HCV1. Group 1 isolates could be found in five patients and the two blood donors. Group 2 isolates could be found in the two other patients. Finally, we could observe neither nucleotide insertion nor deletion in the isolates described here.

Hepatitis C virus confirmation in blood donor screening

A combination of different enzyme immunoassays (EIAs) was used for the serological confirmation of sera that were positive in a hepatitis C virus (HCV) second-generation screening EIA. Different reaction patterns were related with the probability of the HCV-carrier state as determined by polymerase chain reaction (PCR). Five hundred and eight sera of volunteer blood donors were send for confirmation and at first reexamined with both Abbott and Ortho second-generation screening EIA. A group of 195 sera, positive in both assays, was further evaluated by the Abbott Supplemental Assay, the Monolisa anti-HCV and an EIA with only the amino terminal part of the nucleocapsid protein as antigen. In addition PCR on the 5'-noncoding region of the viral genome was performed. We observed that 75 of the 78 PCR-positive sera were found in a group of 89 sera that were strongly positive in the four EIAs used. Moreover all but 1 PCR-positive sera were reactive against the nucleocapsid protein of the virus. Hence we concluded that a genuine antibody response to the nucleocapsid protein is highly suggestive for the HCV-carrier state.