A combined system comprising two separate components, wherein a first component is a vector carrying variable and constant (V-C) T-cell receptor gene segments, and a second component is a vector carrying joining TCR gene segments, wherein the first component is a V-C entry vector containing a. origin of replication, b. a first positive selection marker c. 5' genetic element, or elements, d. Kozak Sequence, e. TCR variable gene segment, f. a first Type IIS sequence, for site specific recognition and cleavage by a first Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves 5' of said recognition sequence and at the 3' end of the TCR variable gene segment, g. a negative selection marker, h. a second Type IIS sequence for site specific recognition and cleavage by a second Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves to direct cleavage 3' of said recognition sequence and at the 5' end of the TCR constant gene segment,. i. TCR constant gene segment, and j. 3' genetic element, or elements, wherein the second component is a J donor vector containing a. origin of replication, b. a second positive selection marker, c. a third Type IIS sequence for site specific recognition and cleavage by a third Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves 3' of said recognition sequence and at the 5' end of the TCR joining gene segment, d. TCR Joining gene segment, e. A C-part, corresponding to a small 5' portion of a constant gene segment, and f. a fourth Type IIS sequence for site specific recognition and cleavage by fourth Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves 5' of said recognition sequence and at the 3' end TCR C-part portion of the construct, such that the single strand overhang sequence generated is complimentary with that generated by said second Type IIS sequence. a. origin of replication, b. a first positive selection marker c. 5' genetic element, or elements, d. Kozak Sequence, e. TCR variable gene segment, f. a first Type IIS sequence, for site specific recognition and cleavage by a first Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves 5' of said recognition sequence and at the 3' end of the TCR variable gene segment, g. a negative selection marker, h. a second Type IIS sequence for site specific recognition and cleavage by a second Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves to direct cleavage 3' of said recognition sequence and at the 5' end of the TCR constant gene segment,. i. TCR constant gene segment, and j. 3' genetic element, or elements, a. origin of replication, b. a second positive selection marker, c. a third Type IIS sequence for site specific recognition and cleavage by a third Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves 3' of said recognition sequence and at the 5' end of the TCR joining gene segment, d. TCR Joining gene segment, e. A C-part, corresponding to a small 5' portion of a constant gene segment, and f. a fourth Type IIS sequence for site specific recognition and cleavage by fourth Type IIS restriction enzyme, wherein the sequence is orientated such that the enzyme cleaves 5' of said recognition sequence and at the 3' end TCR C-part portion of the construct, such that the single strand overhang sequence generated is complimentary with that generated by said second Type IIS sequence.