Absence of human T-lymphotropic virus type I tax sequences in a populationof normal blood donors in the Baltimore, MD/Washington, DC, area: results from a multicenter study

BACKGROUND: It was reported recently that sequences corresponding to the hu man T-lymphotropic virus type I (HTLV-I) tax gene were detected in peripher al blood mononuclear cells from 8 to 11 percent of healthy blood donors wit hout detectable antibodies to HTLV-I. A multicenter blind study was conduct ed to determine if these results could be independently confirmed. STUDY DESIGN AND METHODS: Specimens were collected from 100 anti-HTLV-I-neg ative healthy blood donors and from 11 anti-HTLV-I- or anti-HTLV-II-positiv e individuals. All samples were coded and distributed to each of four indep endent testing laboratories for polymerase chain reaction analysis to detec t sequences of the HTLV-I or HTLV-II fax gene, using detailed procedures sp ecified by the laboratory reporting the original observation. Each laborato ry also tested a dilution panel of a plasmid containing HTLV-I tax to deter mine the analytical sensitivity of the procedure. RESULTS: The analytical sensitivity of the screening methods permitted dete ction of as few as 1 to 10 copies of the fax gene. However, HTLV-I tax sequ ences could not be detected in any of the anti-HTLV-I-negative blood donors at more than one test site. CONCLUSION: HTLV-I tax sequences appear not to be present in this populatio n of 100 blood donors negative for anti-HTLV-I.