Effects of fixation and varying target length on the sensitivity of polymerase chain reaction for detection of human T-cell leukemia virus type I proviral DNA in formalin-fixed tissue sections.

In this study, the fixation condition most suitable for maintaining the sensitivity of the polymerase chain reaction (PCR) was investigated by using the alpha-tubulin gene sequence, and the PCR procedure most effective for detecting human T-cell leukemia virus type I (HTLV-I) proviral sequences in fixed, embedded tissues of adult T-cell leukemia patients was explored. First, the sensitivity of the PCR targeting a 286-bp alpha-tubulin sequence was studied in tissue sections fixed in several fixatives for various periods at 25 or 4 degrees C. For histological examination, fixation with 10% buffered formalin at a lower temperature for a shorter period was found to be preferable to retain the sensitivity. And the HTLV-I sequence was detected in only 7 of 18 specimens (38.9%) when the 374-bp sequence of the gag region was targeted, but the rate increased to 77.8% (14 of 18 specimens) when the length of the target sequence was reduced to 120 bp within the same region. Therefore, the one-round PCR targeting a shorter sequence is preferable for application of PCR to archival fixed tissue specimens, the fixation condition of which may not be ideal for DNA preservation.