新城疫病毒HN标记疫苗的构建及免疫效力

Construction and Immune Efficacy of one HN Marker Vaccine Against Newcastle Disease Virus Infection

将新城疫病毒AI4株的HN蛋白胞外区替换成禽副黏病毒2型T4株HN相应部分,构建获得了一株重组病毒r AI4-T4HNECD,该病毒具有较高繁殖性能,且毒力弱。将该病毒制成灭活疫苗免疫2周龄SPF鸡后,定期采血用于血凝抑制试验(HI),免疫后3周以基因Ⅶd亚型NDV强毒株JS-5-05攻毒,攻毒后定期采血用于HI检测。结果显示:免疫后,该疫苗可有效诱导抗体的产生,并能提供较强的免疫保护。血清学测定数据显示:攻毒前,免疫组鸡血清对AI4株的HI平均效价低于2 log2,但感染后第5、7天免疫组鸡血清对AI4株的HI平均效价可分别达4.3 log2和9.4 log2,而免疫未攻毒组对AI4株的HI效价仍低于2 log2,根据血清对AI4株HI效价的变化可区分免疫动物和感染动物。因此,重组病毒rAI4-T4HNECD可用于新城疫标记疫苗的开发。

The HN ectodomain of Newcastle disease virus(NDV)strain AI4 was replaced with the corresponding part of one avian paramyxovirus serotype-2 strain T4,and one recombinant virus rAI4-T4 HNECD was generated thereafter via reverse genetic technology.The recombinant virus exhibited high yields and low pathogenicity.Two-week-old SPF chickens were immunized with the inactivated vaccine developed with this recombinant virus,and the sera collected periodically were subjected to hemagglutination inhibition(HI)test.Three weeks post-immunization,the chickens were challenged with a virulent strain JS-5-05,and the sera collected periodically were subjected to HI test post-challenge.The results showed that the vaccine could induce the antibody effectively and provide protection against virulent NDV infection.Serological detection data showed that the average HI titer of sera from the vaccinated chickens was lower than 2 log2 before challenge with NDV AI4 strain as detection antigen.Noticeably,on days 5 and 7 days post-challenge,the average HI titer of immunized chickens reached 4.3 log2 and 9.4 log2,respectively.While the HI titer of the sera from immunized chickens without challenge was still lower than 2 log2.According to the alteration of HI titer against the AI4 strain,vaccinated and infected chickens could be effectively differentiated.Therefore,the recombinant virus rAI4-T4 HNECD could be used for developing a ND-marker vaccine.