In a way you can say all av software progs can protect theirselfs, but you must at least have the on-access scan enabled so it will intercept a virus when is enters your comp. Also scan everything you download before opening/using it. In this way you could say avast is ‘inmune’ to virusses. Ofcourse you have to make sure you update the avs on a reguarly base. If av software get’s infected/disabled this is mostly a error from the user who did not setup his protection correctly.