Fig. 2

IS distribution downstream the LTR used for the PCR amplification with decreasing sequence counts. Clusters of putative vector IS were grouped in ensembles as described in material and methods. The abundance of the relative percent in sequence count of putative IS in each different position of each ensemble was calculated as the average of the relative percentage of sequence count for each putative IS on the total reads associated to each ensemble. Downstream vector IS the abundance is relatively high and decreases progressively with the distance. Both the asymmetric distribution with respect the LTR orientation and the gradual decrease in abundance in function of the distance in forward orientation (a) and reverse orientation (b) indicate that these putative IS are false positives