新城疫病毒弱毒株对鹅的免疫效力试验

Immune efficacy of attenuated newcastle disease virus strains on geese

用新城疫病毒(NDV)疫苗株La Sota和NDV基因Ⅶ型致弱株AND/Ⅶ为免疫原,分别以活苗和灭活苗的形式免疫2周龄试验鹅,免疫后第7、14天和21天采血分离血清用于抗体效价测定。免疫后3周以基因Ⅶ型强毒分离株JS2-06进行攻毒,攻毒后每天观察各组鹅的发病情况,并于第2、4天和7天分别采集喉气管和泄殖腔棉拭样品,用于病毒的分离。试验结果表明,活疫苗免疫后不能产生有效的免疫应答,而灭活苗免疫鹅对强毒的感染具有较强的抵抗能力,但基因Ⅶ型致弱株AND/Ⅶ能更有效抑制鹅体的排毒,其免疫效力明显高于疫苗株La Sota。

Two weeks old geese were immunized with La Sota and A-NDV/Ⅶ,an attenuated genotype Ⅶ newcastle disease virus（NDV） strain,respectively.The blood samples were taken on days 7,14 and 21 post-immunization（pi）,and sera were isolated for HI assays.Three weeks pi,the geese were challenged with a lethal dose of a virulent genotype Ⅶ NDV strain.The clinical signs were then observed daily and the swabs were taken from the laryngeal and cloaca on days 2,4 and 7 post-challenge.The morbidity/mortality and virus shedding from the birds showed that both the live vaccines could not elicit effective immune responses and that killed NDV/Ⅶ could provide better immune protection than La Sota in terms of the viral shedding from the vaccinated birds.