Trusses are usually designed to be supported only by the outer walls of the structure with none of the load being transmitted to internal walls.
The bottom chord of the truss is designed with an inbuilt camber to suit the span and load. This camber is progressively taken up as the load is applied (ie, the roofing and ceiling).
Wall frames of non load-bearing internal walls must therefore be constructed to allow free movement of the trusses as they are loaded and unless otherwise specified a truss must not be supported at any intermediate point along its span.