The mean genetic distance (MGD) of Env-V3, Vpr, LTR, and Tat of the X4 and R5 groups.

The MGD of Env-V3, Vpr, and Tat were determined from pairwise genetic distance analyses conducted using the JTT matrix-based model. The LTR divergence was determined using the maximum composite likelihood model. The rate variation among sites for both models was reproduced with a gamma distribution (shape parameter = 6). All evolutionary analyses involved 103 sequences and were conducted in MEGA5.The mean genetic distance (MGD) of Env-V3, Vpr, LTR, and Tat of the X4 and R5 groups.