FIGURE 4.

Human T cell leukemia virus type 1 (HTLV-1) provirus is detected in immature thymocytes and higher PVL is found in more mature thymocytes. The cells isolated from the thymus of four animals infected at the age of 4 weeks and sacrificed at 18 weeks (#594 and #595) or 31 weeks (# 586 and #589) were sorted on their expression of CD3. Proviral load (PVL) was measured on the DNA extracted form the two sorted populations. Except for the mouse #594, the PVL in the CD3⁺ populations is higher. PVL is defined as the number of copies of HTLV-1 in 100,000 human cells.