Gel electrophoresis of polymerase chain reaction product for the infants aged 9 to 12 months. Number 1 is a negative control of PCR, numbers 2, 3, 4, 5, and 7 are HTLV1 TAX negative samples, number 8 is HTLV1 TAX-positive sample which showed 256 bp fragment of HTLV1 TAX gene. Number 6 is a 100 bp DNA size marker and number 9 is a positive control of PCR. All samples (numbers 2, 3, 4, 5, 7, and 8) and positive control of PCR (number 9) showed a 149 bp fragment of human TATA-binding protein gene as an internal control of the PCR.