EXPRESSION AND CHARACTERIZATION OF PROTEINS PRODUCED BY MESSENGER-RNAS SPLICED INTO THE X-REGION OF THE HUMAN T-CELL LEUKEMIA LYMPHOTROPIC VIRUS TYPE-II

In previous studies we showed that human T-cell leukemia/lymphotropic virus type I (HTLV-I) may produce novel proteins encoded in the X region. To investigate a possible correlation between expression of viral genes and different biologic properties of HTLV-I and HTLV-II, we analyzed expression of HTLV-II in the chronically infected cell line MoT. Reverse transcription-polymerase chain reaction analyses revealed that the virus produces several mRNAs singly or doubly spliced into the X region. Corresponding cDNAs were cloned and transfected into a HeLa cell line; resulting proteins were designated according to their sizes and coding open reading frames (ORFs). p10(xI) and p11(xV) were produced by a dicistronic doubly spliced mRNA. p10(xI) was generated by translation of the first exon of rex linked to the x-I ORF; p11(xV) was translated from the tax initiation codon linked to the x-V ORF. Two singly spliced polycistronic mRNAs produced p28(xII), coded by the x-ll ORF, and several isoforms generated by initiation within the x-lll ORF. Studies of the proteins' subcellular localization revealed that they exhibited distinct targeting patterns. Comparison of these proteins with their HTLV-I counterparts indicated intriguing differences between these two viruses, suggesting that further study of the X region products may aid in defining genetic determinants of pathogenicity. (C) 1995 Academic Press, Inc.