Laboratory characterization of human T cell lymphotropic virus types 1 (HTLV-1) and 2 (HTLV-2) infections in blood donors from Sao Paulo, Brazil.

Blood donors in Brazil have recently begun to be screened for infection with HTLV types 1 and 2. Of 351639 blood donations screened in Sao Paulo from January 1992 to October 1993 1063 positive and 2238 indeterminate samples were identified based upon serologic confirmation using the 21e Western blot. Detailed serologic molecular and virologic analysis based upon a laboratory diagnostic algorithm for the characterization of HTLV-1 and HTLV-2 infections was conducted upon 50 seropositive or seroindeterminate blood donors. 2.3 Western blot serologic assays which incorporate type-specific recombinant peptides performed in 29 HTLV 1/2 positive and 21 HTLV 1/2 indeterminate donors with the 21e Western blot identified 25 as infected with HTLV-1 4 with HTLV-2 5 with untypeable HTLV 1/2 15 as HTLV 1/2 indeterminate and 1 as seronegative. Polymerase chain reaction (PCR) analysis using DNA amplification of proviral pol and tax sequences from peripheral blood mononuclear cells confirmed HTLV-1 and HTLV-2 infections in all 2.3 Western blot seropositive donors. Of the 5 serologically untypeable donors 3 were found to be HTLV-1-positive 1 HTLV-2-positive and 1 negative by PCR. All seroindeterminate donors were also negative by PCR. HTLV-1 could be isolated in cocultures from 10 of 18 infected donors.