CELL-MEDIATED TRANSMISSION OF HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE-I TO HUMAN-MALIGNANT TROPHOBLASTIC CELLS RESULTS IN LONG-TERM PERSISTENTINFECTION

We investigated permissiveness of the malignantly transformed trophobl ast (choriocarcinoma) cell lines JAR, BeWo and JEG-3 to the human T ce ll lymphotropic virus type I (HTLV-I). After co-culture with the produ ctively infected cell line MT-2 the choriocarcinoma cell lines were an alysed for infection over a period of three months. The presence of HT LV-I viral DNA was examined by PCR using primers targeting the gag, po l, env and pX specific sequences. Ah amplified segments were found con sistently in the cell cultures throughout the period of study. Further analysis that aimed to characterize the size variation of the integra ted proviral DNA by Southern blotting revealed the presence of integra ted proviral sequences which consisted, for the most part, of incomple te genomes. The presence of the full-length HTLV-I genome, however, wa s unequivocally confirmed in clonally expanded cell cultures derived f rom the originally infected parental cells. In order to analyse virus expression at the transcriptional level, we used reverse transcriptase (RT)mediated PCR that was targeted at intra-exon regions (gag, pol, e nv and pX), and the splicing sites of the env and pX-tax/rex mRNAs. Wh en compared with MT-2 cells, substantially lower levels of all transcr ipts were found in all the cell lines analysed. We were unsuccessful i n attempts to detect viral protein expression using polyvalent or Tax- and Gag-specific monoclonal antibodies by Western blot analysis or im munoprecipitation, and we could not detect any RT activity released in to the supernatant of the infected cells either. Collectively, these d ata suggest that the trophoblastic cells may become persistently but e ssentially non-productively infected with HTLV-I.