ObjectiveTo acquire cDNA sequence of tree shrew CXCR4 and to understand whether tree shrew CXCR4 (tsCXCR4) supports the HIV_1 binding. MethodsThe corresponding designed primers, RT_PCR, gene cloning, DNA sequencing analysis were used. ResultsThe clone of full_length tsCXCR4 cDNA is 1059bp. The homology of tsCXCR4 with that of human CXCR4 (hCXCR4) is 92 8% at nucleotide level and 96 9% at deduced amino acid level. Tyr residues are at positions 7 and 12, and Glu residues are at positions 14,15 and 32 in th e NH 2 _terminal extracellular domain of the tsCXCR4. In addition, Arg residues at positions 183 and 188, and Asp residues at positions 193, 262 and 97 are found in the extracellular loops and transmembrane domains of the tsCXCR4, the above residues are the same as hCXCR4, and are essential for the function of hCXCR4. ConclusionThese results suggest that tsCXCR4 may contribute to the entry of X4 and R5X4 strains of HIV_1.