An apparatus for treating a packaging element having a sub-area that includes a packaging-element opening includes an enclosure having an outer load-bearing structure having load-bearing elements and a wall structure held in the load-bearing structure and isolated by the load-bearing structure from loads. It also has two subsections, one on and moving with a conveyor and the other on a device frame and not moving with the conveyor. The enclosure defines a sterile interior that contains the packaging-element opening. The conveyor moves the packaging element along a transport route in a transport direction. Supports of the load-bearing structure extend transversely to the transport direction and connect to a longitudinal chord oriented along the transport direction. Either the load-bearing structure is disposed outside the enclosure and spaced apart from the enclosure or the transport route includes a circular conformation and a ring forming the longitudinal chord.