Differential Tax expression in HTLV type I-infected asymptomatic carriers.

tax gene expression in a family cluster of three HTLV-I-infected asymptomatic individuals was investigated. Two carriers had normal tax mRNA, Tax-specific humoral antibody, and cell-mediated immune (CMI) response. In one carrier who had only weak Tax-specific humoral and no Tax-specific CMI response, an abnormal Tax-related mRNA product was detected. This product was sequenced and found to consist of two exons derived from the LTR gag and pX regions. The abnormal mRNA has an ORF predicting a 17-kDa protein, the translation of which is initiated in the first exon. The presence of this protein, of antibody to it, and of its function remain to be elucidated.