Analysis of the May 5, 1997 Performance Evaluation Testing Results for Human T-lymphotropic Virus Types I and II Antibody

This report is an analysis of results provided to the Centers for Disease Control and Prevention (CDC) by participant laboratories in the Model Performance Evaluation Program (MPEP) after they tested the human T-lymphotropic virus types I and II (HTLV-I/II) performance evaluation samples shipped to them on May 5, 1997. Testing results for this analysis were provided by 185 (86.4%) of 214 laboratories sent sample panels. Two laboratories returned result booklets with no testing results, and two laboratories returned results more than three weeks past the cutoff date. Data from these 4 laboratories are not included in this report. The testing results reported by the participant laboratories reflect their testing performance using manufactured kits to test performance evaluation samples and do not necessarily reflect an evaluation of these manufactured kits. Samples in this shipment consisted of plasma from donors who were HTLVI/II antibody-negative (donor numbers 9-16) and donors antibody-positive for either HTLV-I or HTLV-II (donor numbers 1-8). Not all laboratories participating in this survey received identical samples, but each laboratory did receive the same number of HTLV-I/II antibody-positive and antibody-negative samples. Before shipment each donor sample was tested with three HTLV lysate-based enzyme immunoassay (EIA) kits licensed by the Food and Drug Administration (FDA) and with two HTLV Western blot (WB) kits. Additionally, each HTLV-I/II antibody-positive donor sample was tested by radioimmunoprecipitation assay (RIPA) and with an indirect immunofluorescent (IIF) antibody assay that can differentiate antibodies specific for HTLV-I or HTLV-II. Donor sample reactivity was determined by the CDC based on composite EIA, WB, and RIPA testing. The CDC MPEP interpretation of WB reactivity for each donor sample was consistent with the kit manufacturers’ criteria for interpretation of WB results.