s[J].J Virol,1990,64:1441—1450.Р[27] Reddy S K,Sharma J M,Ahmad J,et a1.Protective efficacy of a binant herpesvims of turkeys as an in OVO ine against Newcasde and Marek S diseases in specific—pathogen—flee chickens[J].ine,1996,14(6):469—477Р[28] Alexander D J,Collinns M s.The structural polypeptides of avian paramyxovirses[J].Arch Virol,1981,67:309—323.Р[29]Hanson R P.Heterogeneity within strains of Newcastle disease virus:Key tO surviva1.In D.J.Alexander (ed).Newcasde Disease. K1uwer Academic Publishers,Boston,MA ,1988,113—130.Р[30]Foster H A,Chitukuro H R ,Tuppa E,et a1.Thermostable Newcasde disease ine in Tanzania[J].Vet Microbiol,1999,68 (1—2):127—130.Р[31] King I) J.Selection of thermostable Newc~de disease virus progeny from reference and ine strains U].Avian Dis,2001,45(2):512—516.