DELETED HTLV-1 PROVIRUS IN CORD-BLOOD SAMPLES OF BABIES BORN TO HTLV-1-CARRIER MOTHERS

We screened 596 cord-blood samples by nested short PCRs for the gag an d pX regions of HTLV-1 which are capable of detecting a single copy. T he samples were derived from 449 and 147 babies born to seropositive a nd seronegative mothers respectively. Of these, 20 samples were positi ve in at least one of the PCRs: 9 (45%) were positive in both PCRs, bu t 10 and 1 samples in either the pX or the gag PCR respectively. These samples were tested further in nested long PCRs directed for gag-pX, gag-pol and pol-pX regions capable of detecting 8, 1 and 2 copies resp ectively. Of 9 dually positive samples, 7 (77%) showed the predicted 6 .2-kbp band in the gag-pX PCR; only 2 of them had the predicted band a lone; 7 samples had discrete bands shorter than the predicted size. In the gag-pol PCR, all 9 samples showed the predicted 2.2-kbp band alon e. In the pol-pX PCR, 8/9 samples showed the predicted 4.2-kbp band, i ncluding one with an additional 2.1-kbp band, and the last a 1.0-kbp b and alone. Thus, all of the dually positive samples had proviruses har boring Keg, pol and PX priming sites. In contrast, none of the 11 sing ly positive samples showed the predicted band in the gag-pX PCR: 5 had no visible band, and the other 6 had shorter bands only. None of thes e 11 samples showed any positive signal in either gag-pol or pol-pX PC R. Our results suggest that HTLV-1 proviruses in the cord blood are fr equently defective. (C) 1998 Wiley-Liss, Inc.