  We define an elliptic deformation of the Virasoro algebra. We argue that the
$\mathbb{R}^4\times \mathbb{T}^2$ Nekrasov partition function reproduces the
chiral blocks of this algebra. We support this proposal by showing that at
special points in the moduli space the 6d Nekrasov partition function reduces
to the partition function of a 4d vortex theory supported on
$\mathbb{R}^2\times \mathbb{T}^2$, which is in turn captured by a free field
correlator of vertex operators and screening charges of the elliptic Virasoro
algebra.
