EVALUATION OF 2 COMMERCIAL HUMAN T-CELL LYMPHOTROPIC VIRUS WESTERN-BLOT (IMMUNOBLOT) KITS WITH PROBLEM SPECIMENS

We evaluated two commercial human T-cell lymphotropic virus (HTLV) Wes tern blot (WB; immunoblot) kits, Cambridge Biotech Corp. (CBC) and Dia gnostic Biotechnology Ltd. (DBL). Both methods employ HTLV type I (HTL V-I) viral lysate and rgp21. The DBL WB kit also distinguishes between HTLV-I and HTLV-II antibodies, using an HTLV-I-specific and an HTLV-I I-speific recombinant. Fifty weakly reactive HTLV-II-positive plasma s pecimens which were falsely negative with the Abbott enzyme immunoassa y (EIA) and 50 Ortho EIA false-positive samples were selected to deter mine sensitivity and specificity. The sensitivities of the CBC and the DBL WB kits were 90 and 68%, respectively. All positive samples react ed with rgp21 in both kits, but some did not display core bands. Five samples were typed as HTLV-I and four were typed as dual infection by the DBL WB kit. The specificities of the CBC and DBL kits were 48 and 70%, respectively. The most prevalent WB reaction with the negative sa mples was with the core protein, p19, followed by p24 and p28 for CBC and rgp21 and p28 for DBL. DBL had two false-positive interpretations, and CBC had none, rgp21 was the most sensitive antigen in both kits f or the weakly reactive HTLV-II samples. If all samples not reacting wi th this protein were interpreted as WB negative, regardless of other b ands, the specificity would improve to 90% for CBC and 86% for DBL.