Expression of distant host genes correlates with expression of tax.

(A) Normalized mRNA read counts of two genes that lie >1.4 Mb from the provirus in clone Timer-TBX4B, in the four successive phases of the HTLV-1 plus-strand transcriptional burst: DN–double negative (HTLV-1 silent); blue–early burst; DP double-positive (mid-burst); red–late burst. Results of two independent experiments are shown. Expression of both SMC1B and RIBC2 closely followed the trajectory of the HTLV-1 burst in clone Timer-TBX4B, but not in the unrelated HTLV-1-infected clone Timer-3.60. Data from [11]. (B) Knockout of the CTCF binding site in the provirus in clone Timer-TBX4B (middle panel) abolished the transcription of both SMC1B and RIBC2 observed in the wild-type clone (lower panel). Results of two independent experiments are shown. Neither gene was expressed in an unrelated HTLV-1-infected clone ED. The results suggest that maintenance of a CTCF-dependent chromatin loop between the host genome and the provirus is required for the burst of transcription of these distant genes associated with the HTLV-1 plus-strand burst.

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