T cell lines and clones play a key role in basic studies of cellular immunology, and are also finding applications in adoptive immunotherapy. However, with proliferative expansion, T cells ultimately undergo cellular senescence and death, so that long-term culture of T cell clones is difficult to achieve. Expression of telomerase reverse transcriptase (TERT) in differentiated cells can maintain telomere length over many cell divisions, preventing senescence. We used a retroviral vector that expresses the human TERT (hTERT) gene to transduce a rhesus macaque-derived CD8(+) T cell clone specific for the MamuA*01-restricted immunodominant SIV gag epitope CM9. Extensive in vitro characterization revealed that the untransduced parental cells and the hTERT-transduced cells displayed comparable proliferation capacity, effector memory surface marker profiles, cytolytic activities, and cytokine profiles following antigen stimulation. The hTERT-transduced cells showed improved survival compared to parallel nontransduced cultures during in vitro propagation in long-term culture. Such immortalized T cells may be useful as a source of consistent controls for in vitro assays of cellular immune function, and as a potentially important reagent for autologous adoptive cellular immunotherapy studies in macaques.