<prompt> The receptor through which M-tropic HIV strains bind -CCR5CXCR4CXCR5Any of the above  <response>: HIV-1 most commonly uses the chemokine receptors CCR5 andor CXCR4 as co-receptors to enter target immunological cells. Option 1: Macrophage M-tropic strains of HIV-1, or non-syncitia-inducing strains NSI use the beta-chemokine receptor CCR5 for entry and are thus able to replicate in macrophages and CD4 T-cells. These strains are now called R5 viruses. Option 2: T-cell line T-tropic isolates or syncytium-inducing SI strains replicate in primary CD4 T-cells as well as in macrophages and use the alpha-chemokine receptor, CXCR4, for entry. Option 3: CXCR5 in B-cell and tumor cell responses: expressed in Burkitt Lymphoma and Intraocular Lymphoma. 