Multiple choice Which strains exclusively use CxCR4 receptors for entry into host cells? Dual tropic strains M-tropic strains T-tropic strains All of the above Reveal answer Fill a bubble to check yourself C Correct answer Explanation T-tropic strains replicate in primary CD4+ T-cells as well as in macrophages and use the alpha-chemokine receptor, CXCR4, for entry into cells.