Comparison of the number of CISs found in the SIV rhesus insertion dataset long term compared with 10 000 random datasets. CISs of second, third, and fourth order were identified in the SIV dataset and in the 10 000 random datasets as defined and described in “Identification and analysis of vector insertion sites.” The x-axis gives the number of CISs and the y-axis, the number of datasets containing that number of CISs. The arrows show the number of each order CIS found in the experimental SIV datasets. P values were all less than .001 comparing second-, third-, and fourth-order CISs in the SIV experimental dataset to the 10 000 random datasets.