FIG 5.

Summary of the contribution of monocyte subsets to HTLV-1 persistence. This cartoon summarizes the results of our correlative analysis of the HTLV-1 DNA burden in the three monocyte subsets and either their functions (migration and phagocytosis) or the level of viral DNA in CD8⁺ and CD4⁺ T cells. Briefly, the hypothesis is that in HTLV-1 infection, more classical monocytes leave the blood and go to tissues, where they acquire HTLV-1 infection. Similarly intermediate monocytes more often migrate to inflammatory sites in tissue in response to CCL5, but their phagocytic function decreases and their virus burden increases. Lastly, nonclassical monocyte levels increase in blood, and the virus burden in nonclassical monocytes reflects that in CD4⁺ and CD8⁺ T cells.