tokens: CXCR4 is a chemokine receptor and a coreceptor for T-cell-line-tropic ( X4 ) and dual-tropic ( R5X4 ) human immunodeficiency virus type 1 ( HIV-1 ) isolates .
folded_tokens: cxcr4 be a chemokine receptor and a coreceptor for t-cell-line-tropic ( x4 ) and dual-tropic ( r5x4 ) human immunodeficiency virus type 1 ( hiv-1 ) isolate .