The invention relates to screening methods. In particular, it relates to a method of identifying a functional TCR from a
library of particles, which displays a plurality of different
T cell receptors (TCRs). The method may comprise a) exposing the
library of particles to a
target antigen to identify TCRs that bind to the
target antigen, b) transfecting a plurality of T cells with
nucleic acid encoding TCRs identified in step (a), c) exposing the plurality of transfected cells to the
target antigen, and d) selecting cells having TCR activity in the presence of the target
antigen.
Transfection of the T cells is such that each
T cell comprises a
nucleic acid encoding a single TCR from the
library of particles, the
nucleic acid is integrated into the
genome of the
T cell at a single identical pre-defined locus, and the TCR is in a
single chain format and comprises an
alpha chain variable domain, a beta cain
variable domain and a
constant domain. The T cells do not express endogenous TCR. A T-
cell comprising a
recombinase mediated landing pad, wherein the T
cell constitutively expresses TCR
constant domain and does not express endogenous TCR, is also claimed.