Christine Defer

Sensitivity of HCV RNA and HIV RNA blood screening assays

BACKGROUND: The FDA requirement for sensitivity of viral NAT methods used in blood screening is a 95‐percent detection limit of 100 copies per mL, whereas the NAT screening system should have a sensitivity of at least 5000 copies per mL per individual donation. According to the Common Technical Specifications of the European Directive 98/79/EC for in vitro diagnostics, viral standard dilutions (calibrated against the WHO standard) should be tested at least 24 times for a statistically valid assessment of the 95‐percent detection limit.

A new HCV core antigen assay based on disassociation of immune complexes: an alternative to molecular biology in the diagnosis of early HCV infection

BACKGROUND: An EIA based on immune complex disassociation of nucleocapsid proteins of HCV has been developed to detect and quantify HCV core antigen.

Evaluation of the enhanced bacterial detection system for screening of contaminated platelets

BACKGROUND:  The Pall third‐generation enhanced bacterial detection system (eBDS) was recently approved for detection of bacterial contamination in leukoreduced platelets (PLTs). The method is based on the measurement of the oxygen content as a marker for bacteria. eBDS incorporates major modifications including removal of the sample‐set filter, modification of the culture medium, and incubation with agitation of the sample pouch.

Screening blood donations for viral genomes: multicenter study of real- time simulation using pooled samples on the model of hepatitis C virus RNA detection

BACKGROUND: The systematic screening for several blood‐borne viral genomes in blood donations is a complementary safety measure planned or discussed by the national authorities of several countries.

Contribution of polymerase chain reaction and radioimmunoprecipitation assay in the confirmation of human T-lymphotropic virus infection in French blood donors

BACKGROUND: To verify the criteria for human T‐lymphotropic virus (HTLV) seropositivity in Western blot (WB) proposed by the Retrovirus Study Group of the French Society of Blood Transfusion, 186 blood donations that were repeatedly reactive in HTLV enzyme‐linked immunosorbent assay, selected according to their WB pattern, were tested by polymerase chain reaction (PCR) and radioimmunoprecipitation assay (RIPA).

Screening for HBV, HCV and HIV genomes in blood donations : shortcomings of pooling revealed by a multicentre study simulating real-time testing

This study was undertaken in order to determine whether screening of viremic blood donations by testing of pooled donor samples could constitute a technically feasible transfusional safety measure. A pilot study of real-time simulation, on a day-to-day basis, of screening of three viral genomes (hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV)) was conducted by five French Blood Centers on plasma samples collected from blood donors and studied within undiluted samples and within sample pools of various sizes. This study was carried out within time conditions compatible with the release of platelets. For the detection of HCV and HIV genomes, the five laboratories achieved a sensitivity that decreased with the size of the sample pool. Four were successful in detecting all undiluted samples. In the 1/10 diluted samples, four failed to detect one HIV or HCV sample. In the 1/100 diluted samples, all laboratories failed to detect one or more HIV or HCV samples. For HBV genome, no participating laboratories detected all of the samples of the panel, even undiluted samples, and the sample pooling considerably affected sensitivity. The improvement and standardization of assays needs to be attained, and training of laboratories appears to be a step crucial for routine screening of viral genomes in blood donations.

Expertise of French Laboratories in Detection, Genotyping, and Quantification of Hepatitis C Virus RNA in Serum

ABSTRACT Before initiating new large-scale therapeutic trials for hepatitis C virus (HCV)-infected patients, the French Health Authorities for HCV research decided to organize an evaluation of the expertise of laboratories that could be engaged to undertake molecular biology assays in such trials; 21 experienced laboratories participated in this national evaluation of laboratory expertise, which was performed in two successive rounds. The first round evaluated the laboratories for their abilities to detect HCV RNA in serum, determine genotypes, and quantify HCV RNA loads. The results observed by qualitative assays for HCV RNA detection were 100% sensitivity and 100% specificity for all laboratories. The genotyping results were 100% concordant for 9 laboratories and greater than 90% for 10 laboratories. By contrast, large coefficients of variation were observed for quantitative determination of HCV RNA loads, leading to a second round with standardized quantitative assays only. The dispersion of the results was larger by the AMPLICOR HCV Monitor assay than by the branched-DNA assay (mean coefficients of variation, 57.4 and 16.9%, respectively). In the majority of cases, discrepancies between the results of the two tests were found for samples with high viral loads. These results indicate the usefulness of validating, by controlling for expertise, both the reliabilities of laboratories involved in multicenter work and the standardized assays chosen for use in the evaluation of the biological impacts of new therapies.

HCV RNA in blood donors with isolated reactivities by third-generation RIBA

BACKGROUND: The objective of this collaborative study was to learn the proportion of HCV RNA‐positive samples obtained from a population of donors with isolated anti‐HCV reactivities by third‐generation RIBA (RIBA‐3) (indeterminate results).

Indeterminate third-generation recombinant immunoblot assay in hepatitis C virus infection

Third-generation recombinant immunoblot assay is widely used for the validation of the serological diagnosis of hepatitis C virus infection. To determine whether indeterminate recombinant immunoblot assay 3.0 patterns may be associated with viral replication and liver disease, 89 indeterminate patterns were studied (67 c22n 14 c33c, 5 c100p and 3 NS5); 35 (39%) had immunosuppression. Serum alanine aminotransferase activity was increased in 49 (55%); HCV RNA was evidenced through polymerase chain reaction in 52 (58%). The observation of indeterminate recombinant immunoblot assay 3.0 justifies investigation of liver disease and search for HCV RNA, since a large proportion of individuals with such patterns are hepatitis C virus-infected.