A comparison of the performance of nine commercially available anti-HTLV-I screening assays.

The performance of eight anti-HTLV-I enzyme immunoassays (EIAs) and one particle agglutination assay was compared with respect to sensitivity, specificity and delta values, by testing a panel containing 99 anti-HTLV-I positive and 126 anti-HTLV-I negative samples which had been characterised by western blot and some by radioimmunoprecipitation assay. The estimated sensitivities produced by these assays ranged between 99% and 100% and estimated specificities were between 95.2% and 100%. The performance of the EIAs was further differentiated by using the delta value which measures the ability of an assay to separate the positive and negative populations from the cutoff value. A delta value could not be calculated for the particle agglutination assay (Serodia) because the test readings were not quantitative. The EIAs most likely to correctly identify anti-HTLV-I positive and anti-HTLV-I negative samples included the Cambridge Biotech, Dupont, Genetic Systems and Olympus assays. Our findings suggest that there may be some difficulty in correctly identifying anti-HTLV-I negative samples using the Abbott, Cellular Products Incorporated (CPI), Coulter and Diagnostic Biotechnology assays. The Serodia assay produced comparable sensitivity and specificity to the eight EIAs.

HTLV-I among Northern Territory blood donors.

OBJECTIVE: Human T-lymphotropic virus type I (HTLV-I) is known to be endemic among Northern Territory (NT) Aborigines, therefore evidence was sought of HTLV-I infection in NT blood donors. DESIGN: Samples were screened for HTLV-I antibodies using the Serodia HTLV-I particle-agglutination assay. Repeatedly reactive sera were tested by western blot. Viro- logical and molecular investigations were also performed. SERA: Aliquots from all 11,121 blood donations collected between June 1991 and August 1992. RESULTS: Four (0.036% of total) blood donations, each from different donors, were repeatedly reactive by particle-agglutination assay. One (0.009%) sample, from a 52-year-old non-Aboriginal man with no verified risk factors, was confirmed as HTLV-I seropositive by western blot. A viral isolate and a 431 base pair polymerase chain reaction product from the env gene were obtained from a culture of his peripheral blood mononuclear cells. Sequencing of the polymerase chain reaction product demonstrates that this isolate is a prototype strain and not the variant identified among Aborigines. The remaining three repeatedly reactive donors, including the positive donor's wife, were western blot indeterminate. CONCLUSIONS: There is a low prevalence of HTLV-I carriage among blood donors in the NT, and presumably in other States. However, most repeatedly reactive donations prove to be western blot indeterminate, therefore additional tests are required to detect or exclude HTLV-I infection. Although universal screening of donations would virtually eliminate HTLV-I transmission by transfusion, it has disadvantages, including financial cost.

HTLV-I infection in selected populations in Australia and the western Pacific region.

The prevalence of infection with human T lymphotropic virus type I (HTLV-I) in 19,975 blood samples from Australia and the western Pacific was determined by measuring the presence of specific antibody (anti-HTLV-I) by enzyme-linked immunosorbent assay (ELISA) with confirmation by western blot and/or radioimmunoprecipitation techniques. In Australia no evidence of HTLV-I infection was found in injecting drug users, patients with the acquired immunodeficiency syndrome (AIDS), subjects attending a sexually transmitted diseases clinic, female prostitutes, or transfusion recipients. A low prevalence of infection was detected in people with haemophilia (0.5%) and in male homosexuals (0.5%-1%). No antibody was detected in sera from Vanuatu, Kiribati, American Samoa, the Cook Islands, New Caledonia, the Federated States of Micronesia, French Polynesia and Fiji, but a low frequency of anti-HTLV-I was detected in sera from the Solomon Islands (1.2%) and Nauru (0.6%).