#2050198
Mura mbaineann saintréith ar leith leis an gcaolú (e.g. marcóir géiniteach, cobhsaíocht theirmeach), déantar é sin, de ghnáth, trí easpa fillte ar nimhneacht sa spriocspeiceas ainmhí.
Unless a specific characteristic is associated with the attenuation (e.g. genetic marker, thermal stability), this is typically achieved through absence of reversion to virulence in the target animal species.