  From the defining exchange relations of the A_{q,p}(gl_{N}) elliptic quantum
algebra, we construct subalgebras which can be characterized as q-deformed W_N
algebras. The consistency conditions relating the parameters p,q,N and the
central charge c are shown to be related to the singularity structure of the
functional coefficients defining the exchange relations of specific vertex
operators representations of A_{q,p}({gl_{N}) available when N=2.
