Isolation and identification of high virulent Newcastle disease viruses in Guangxi

Two isolates of virus were isolated from sick or death chickens of two different flocks in a large chicken farm, which could agglutinate chicken red blood cell. These agglutinations were inhibited and these isolates were neutralized by Newcastle disease virus standard antisera. Those isolates were confirmed to be high virulent Newcastle disease virus based on HA, HI test, antisera neutralization test and the detection results of RT-PCR. 50 % embryo lethal dose (ELD_(50)) of these isolates were 10~(-9.38)/0.1 mL and 10~(-9.68)/0.1mL,separately,and mean death time (MDT) of chicken embryos of these isolates were 52, 54 h,separately,Intracerebral pathogenicity index (ICPI) of these isolates in one day old SPF chicken were 1.975, 1.875,separately. The results demonstrated that 2 isolates of virus were high virulent Newcastle disease virus.