Wang L, Suarez D L, Pantin-Jackwood M, Mibayashi M, García-Sastre A, Saif Y M, Lee C-W
Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, United States.
Vaccine. 2008 Jul 4;26(29-30):3580-6. doi: 10.1016/j.vaccine.2008.05.001. Epub 2008 May 22.
From a stock of A/turkey/Oregon/71-delNS1 (H7N3) virus, which has a 10 nucleotide deletion in the coding region of the NS1 gene, we found that several variants with different sizes of NS genes could be produced by passaging the virus in 10- and 14-day-old embryonating chicken eggs (ECE), but not in 7-day-old ECE or Vero cells. We were able to rescue the reassortant virus that has different sizes of the NS genes and confirmed that those NS genes are genetically stable. By conducting in vivo studies in 2-week-old chickens, we found two plaque purified variants (D-del pc3 and pc4) which can be used as a potential live-attenuated vaccine. The variants were highly attenuated in chickens and did not transmit the virus from infected chickens to uninoculated cage mates. At the same time, the variants induced relatively high antibody titers which conferred good protection against a high dose heterologous virus challenge. Our study indicates that naturally selected NS1 deletion variants might be useful in the development of live-attenuated influenza vaccines in poultry. Furthermore, deletion in the NS1 protein can be potentially useful as a negative marker for a differentiating infected from vaccinated animals (DIVA) approach.
从A/火鸡/俄勒冈/71-delNS1（H7N3）病毒株（其NS1基因编码区有10个核苷酸缺失）开始，我们发现通过在10日龄和14日龄的鸡胚（ECE）中传代该病毒可产生几种不同大小NS基因的变体，但在7日龄鸡胚或Vero细胞中传代则不会产生。我们成功拯救出了具有不同大小NS基因的重配病毒，并证实这些NS基因在遗传上是稳定的。通过对2周龄鸡进行体内研究，我们发现了两种蚀斑纯化变体（D-del pc3和pc4），它们可作为潜在的减毒活疫苗。这些变体在鸡中高度减毒，且不会将病毒从感染鸡传播给未接种的同笼鸡。同时，这些变体诱导产生了相对较高的抗体滴度，能有效抵御高剂量异源病毒的攻击。我们的研究表明，自然选择的NS1缺失变体可能有助于家禽减毒活流感疫苗的研发。此外，NS1蛋白的缺失可能作为区分感染动物与接种动物（DIVA）方法的潜在阴性标记。
