4MONTGOMERY D L, SHIVER J W, LEANDER K R,et al. Heter- ologous and homologous protection against influenza A by DNA vac- cination: Optimization of DNA vecters [ J]. DNA Cell Biol, 1993, 12(9) :777 -783.
5YU L, WANG Z L, JIANG Y H, et al. Characterization of newly e-merging Newcastle disease virus isolates from the People' s Republic of China and Taiwan [ J ]. J Clinical Microbiol, 2001 , 39 ( 10 ) : 3512 -3519.
6SCHIED A, CHOPPIN P W. Isolation and purification of the enve- lope proteins of Newcastle disease virus[ J]. J Virol, 1973,11 ( 2 ) : 263 - 271.
7ALEXANDER D J, RUSSELL P H, PAESONS G,et al. Antigenic and biological characterization of avian paramyxovirus type I iso- lates from pigeons an interuational coilaborative study [ J ]. Avian Pathol, 1985,14 ( 3 ) : 365 - 376.
