[Mutations of the hemagglutinin gene of H9N2 subtype avian influenza viruses under selective pressure of antibody].
OBJECTIVE
To understand mutations of avian influenza virus (AIV) under the antibody selective pressures.


METHODS
We continuously passed an H9N2-AIV strain LG1 in embryos with or without maternal antibody to LG1 in 6 separate serials. At the 10th, 20th, 30th, 40th and 50th passages in each serial, H9 hemagglutinatin gene (HA) sequences were determined and compared to the original LG1 strain.


RESULTS
Only unstable random mutations happened in 29 sites with nonsynonymous vs synonymous (N/S) mutation ratio of 1.42 during 50 passages in 2 serials without maternal antibodies. However, multiple stable nonsynonymous mutations were detected gradually during 50 passages of 4 serials in embryos with maternal antibody to LG1 strain, and the NS/S ratio was as high as 3.46 among 45 mutated sites.


CONCLUSIONS
The results suggested that the antibody selective pressure influenced mutations of H9N2 AIV HA gene during the passages in embryos with maternal antibody. Embryos with maternal antibody to certain viruses could be used as experimental models to study the immune selective pressures on viral mutations.
Lou
Benhong
B
College of Animal Science and Technology, Shandong Agricultural University, Tai'an 271018, China.
Zhu
Xiutong
X
Sun
Beibei
B
Cui
Zhizhong
Z
D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology*; D002642:Chick Embryo; D002645:Chickens; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics* / Q000276:immunology; D053127:Influenza A Virus, H9N2 Subtype / Q000235:genetics* / Q000276:immunology; D005585:Influenza in Birds / Q000276:immunology* / Q000821:virology; D009154:Mutation; D012641:Selection, Genetic
D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus