The role of amniotic passage in the egg-adaptation of human influenza virus is revealed by haemagglutinin sequence analyses

• Published in: Journal of general virology 1993-10, Vol.74 (10), p.2047-2051
• Main Authors: Robertson, James S, Nicolson, Carolyn, Major, Diane, Robertson, Edwin W, Wood, John M
• Format: Article
• Language: English
• Subjects: Amnion - microbiology; Animals; Base Sequence; Chick Embryo; Cloning, Molecular; Hemagglutinins, Viral - analysis; Hemagglutinins, Viral - genetics; Humans; influenza B virus; Influenza B virus - genetics; Influenza B virus - growth & development; Molecular Sequence Data; Polymerase Chain Reaction; Serial Passage - methods
• ISSN: 0022-1317; 1465-2099
• DOI: 10.1099/0022-1317-74-10-2047

1 National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG and 2 Medical Centre, 46-62 Bank Street, Alexandria, Dunbartonshire G83 0LS, U.K. Obtaining an isolate of a human influenza virus in the allantoic cavity of the embryonated hen's egg is more efficient if the clinical sample is initially passaged in the amniotic cavity. To investigate the extent to which the variants present after allantoic propagation are also selected by amniotic passage, clinical virus passaged once in the amnion has been subjected to extensive genetic and antigenic analyses. The data indicate that the natural virus can replicate unrestrictedly within the amnion. However, exposure of amniotic virus to the allantois during the incubation period, which will occur through the hole between the amniotic and allantoic cavities caused by the inoculating needle, allows for the possibility of an egg-adapted variant establishing replication within the allantois and returning to the amnion. These observations illustrate why prior passage in the amnion increases the probability of a variant successfully establishing itself during a subsequent allantoic passage. Received 26 February 1993; accepted 24 May 1993.