疫苗免疫压力下新城疫病毒的动态演化

国内大量新城疫病毒(NDV)血凝素基因F和HN的测序表明,NDV主要免疫原HN和F基因与生产中广泛应用的经典疫苗La Sota株的核苷酸同源性不足80%,而NDV流行株之间则高达94.4%～100%,从分子遗传学角度证实了VIId型NDV是导致新城疫免疫失败的重要原因。HI交叉抑制和鸡胚中和试验等则从抗原性的角度证实了NDV在免疫压力下抗原性的变化,尽管NDV不同毒株间抗原性变异的程度已出现明显差异,但仍局限在同一个血清型中。

Evolutionary Dynamics of Newcastle Disease Virus Under the Pressure of Vaccination in China

A series of tests of newcastle disease virus (NDV) have been finished in recent years and the phylogenetic analysis indicated that NDV isolates (NDVs) belonged to genotype VII shared a higher homology of 94.4%~100% in nucleotide acids but less than 80% with the widely used vaccine strain La Sota. Newcastle disease viruses representing different phylogenetic clades were evaluated for their antigenic relatedness by hemagglutination inhibition and virus neutralization tests in embryonating chicken eggs, and the results revealed that most of the recent Chinese isolates belonged to the same serotype but could be classified into distinct subtypes, which suggesting that there were major antigenic differences among NDVs belonging to different sublineages. Collectively, these data supported the hypothesis that the newly emerging genotype VIId were considered to be responsible for the outbreak of newcastle disease in vaccinated chicken flocks.