CXCR4 and viral infectious disease: However T-tropic (HIVIIIB) strains which has CXCR4 co-receptor were susceptible to both compounds and not to the M-tropic (HIV-BaL) strain (Figure 1A-D) due probably at the increased of negative charge (T-tropic) in variable region (V3) of human immunodeficiency virus type 1 (HIV-1) envelope gp120 subunit participates in determination of viral infection coreceptor tropism [25-27].