At day six post infection (Figure 4c), Av-5 was significantly more effective against clinical isolate of clade F at 0.4 μM (p = 0.01) Notably, the clade D isolate contained the R5 × 4 tropism, which can enter target lymphocytes using the cofactors CCR5 or CXCR4, rather than just CCR5, like the R5 viral tropism. Here, CXCR4 is linked to infection.