Suppression of inherent virulence for chickens of a newcastle disease strain by a shift within its subpopulations.
D000818:Animals; D002645:Chickens; D009521:Newcastle Disease / Q000209:etiology*; D009522:Newcastle disease virus / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity*; D014774:Virulence