<p>Background: Tax-1 protein of Human T-cell Leukemia Virus type 1(HTLV-1) serves as a key transcriptional regulatory gene product and has a crucial role in transactivating genes of infected cells by employing their transcriptional factors. This modulation includes induction of genes which encode CC-chemokines and their receptors. In this study, a recombinant vector containing Tax-1 gene was made and tested for its ability to induce CCR5 (CC chemokine receptor 5) expression in K562 cell line.<br /> Methods: In order to perform this research, two blood samples of HTLV-1 positive were obtained from Urmia blood transfusion center. After DNA extraction, a complete sequence of <em>Tax-1</em> gene was amplified by specific primers. Recombinant vectors carrying Tax-1 gene were synthesized and transformed into <em>Escherichia coli (E. coli)</em>. After bacteria transformation, bacteria containing recombinant plasmid were selected and purified. Then, the recombinant shuttle vectors, <em>pCDNA3.1-TAX</em>, were transfected into the cell culture (K562 cell line). Expression of <em>CCR5</em> was measured after 72 <em>hr</em> by Syber Green Real-Time PCR method compared to control cell culture. Normalization was done with GAPDH as a standard gene.<br /> Results: Cloning of <em>Tax-1</em> gene in the vector, <em>pCDNA3</em>.1 was confirmed by colony PCR, restriction digestion, and sequencing methods. Expression of <em>Tax-1</em> and <em>CCR5</em> genes were confirmed by real time PCR and also, expression of <em>CCR5</em> gene showed an 8-fold increase in comparison to mock-treated controls (p&lt;0.05).<br /> Conclusion: Our data suggested that recombinant <em>Tax-1</em> may have the enhancing effect on CCR5 expression rate at mRNA levels in K562 cell line. Further studies are necessary to evaluate the effect of<em> pCDNA3.1-TAX</em> on cell surface CCR5 expression.</p>