title: Improved methods for isolation of avian influenza virus.
abstract: Isolation of viruses using chick embryos is a classical virological method. Inoculation of the allantoic cavity and use of allantoic fluid is a common method of passaging isolated avian influenza viruses. In the present study, 2490 fresh fecal samples and 4967 old fecal samples were investigated and subjected to conventional passaging (allantoic fluid method). Two newly developed methods-the allantochorion and allantoic fluid mixed method and the chick embryo and allantoic fluid mixed method-were also examined. The rates of influenza virus isolation for these three methods were compared. There appeared to be little difference among these methods when fresh fecal samples were used. However, for the old fecal samples, isolation rates for influenza virus were significantly higher for the chick embryo and allantoic fluid mixed method compared with the conventional allantoic fluid method. All viruses isolated using the conventional allantoic fluid method were isolated successfully using the two newly developed methods. These results suggest that using chick embryos in conjunction with allantoic fluid is effective for early virus isolation, especially for fecal samples that are not fresh. Additionally, practical chick embryo passage methods are described that improve significantly the rate of isolation of influenza viruses from fecal samples of migratory birds in a complex wild ecological environment.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Tang
authors.affiliation: Ningbo Key Laboratory of Virus Research, Ningbo Municipal Center for Disease Control and Prevention, Ningbo 315010, China.
authors.forename: Yongdong
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: Han
authors.initials: H
authors.lastname: Xia
authors.affiliation: College of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: Na
authors.initials: N
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
authors.forename: Jiuru
authors.initials: J
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China. Electronic address: litx@wh.iov.cn.
authors.forename: Tianxian
authors.initials: T
authors.lastname: Li
mesh_terms: D000482:Allantois / Q000821:virology; D000818:Animals; D001717:Birds; D002642:Chick Embryo; D005243:Feces / Q000821:virology; D009980:Influenza A virus / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000821:virology*
keywords: Allantoic cavity inoculation; Egg inoculation; Virus isolation