FIG 4.

Mutations in the LTR resulted in a change in the quantity or type of functional sites. (A) The number of AP-1 binding sites in the NRE region per LTR gradually increased during the vaccine development process. (B) The ratios of the seven types of TSSs (color-coded as explained below the graph) were significantly changed at the different stages of vaccine development. (C) The predominant nucleotide of the TAR initiation site shifted from A to G with the attenuation of the host strain. Numbers of LTR clones are given in parentheses.