Detection of HTLV-1 proviral sequences in rabbits inoculated with transfected PBMC. Genomic DNA from PBMC of rabbits inoculated with ACH-(R51-54 and 31-32), ACH.p12- (R55-58 and 33-34), or pKS (vector control)- (R50) transfectants was amplified by PCR using primers specific for HTLV-1 pX (938 bp) or β-actin (415 bp). Sensitivity of the PCR was estimated to be 1 proviral genome per 5,000 cells.