Isolation, identification, and hexon gene characterization of fowl adenoviruses from a contaminated live Newcastle disease virus vaccine

作者：Yang Li, Jiayuan Fu, Shuang Chang, Lichun Fang, Shuai Cui, Shuai Cui, Yixin Wang, Zhizhong Cui, Peng Zhao · 发表于：Poultry Science · 年份：2016 · DOI：10.3382/ps/pew405 · 被引用次数：23 · 研究领域：Virus-based gene therapy research、Viral Infectious Diseases and Gene Expression in Insects、Virology and Viral Diseases

To investigate the possible causes of the massive spread of fowl adenovirus (FAdV) infection among chickens in recent years in China, 32 batches of live-virus vaccines were tested for contamination with FAdV by PCR. Among these, 1 live Newcastle disease virus (NDV) vaccine of the LaSota strain was demonstrated to be positive for contamination. The amplified hexon gene exhibited 99.8% identity with a recent Chinese field isolate (JSJ13) of FAdV-4. The positive LaSota vaccine was first neutralized with anti-NDV serum and then inoculated into specific pathogen-free embryos at embryonic day 5 through the yolk sac for isolation of the contaminated FAdV. The same hexon gene bands were amplified from extracted DNA of the liver tissues and chicken embryo allantoic fluid of the inoculated embryos, indicating the replication and isolation of the FAdV-4 virus strain that had contaminated the vaccine. This represents the first report of FAdV-4 contamination in a live vaccine for poultry in China. These findings suggest that contamination of live vaccine might represent one of the most important causes of massive outbreaks of FAdV infection among chickens and indicate that FAdV should therefore be included in the regular monitoring list for the detection of exogenous viral contamination of attenuated vaccines for poultry.