We consider the 4D Martinez Alonso-Shabat equation epsilon u(ty) = u(z)u(xy) - u(y)u(xz) (also referred to as the universal hierarchy equation) and using its known Lax pair construct two infinite-dimensional differential coverings over epsilon. In these coverings, we give a complete description of the Lie algebras of nonlocal symmetries. In particular, our results generalize the ones obtained in Morozov and Sergyeyev (2014) and contain the constructed there infinite hierarchy of commuting symmetries as a subalgebra in a much bigger Lie algebra.