A Java method that changes the state of an object is called a mutator. Mutators typically do not return a result (are declared to return void), although some mutators both change state and return a result (e.g., nextToken in StringTokenizer). Mutators just change state, without looking at current values, are often call "setters", and their names often start with set. See accessor.
a viral defence mechanism in host cells that may induce either lethal hypermutation or instability of the incoming nascent viral reverse transcripts, which could account for the Vif-defective phenotype