[Do pigs play a role in human infection with avian influenza A H9N2 viruses].
OBJECTIVE
To understand whether pigs play a role in human infection with avian influenza A H9N2 viruses.


METHODS
The target gene was amplified by RT-PCR, and the PCR product was linked to PGEM-T Vector (Promega, USA) at 4 degrees C, the recombined plasmid was transferred into dH5a bacteria, and the positive colonies were selected and identified with restriction endonuclease. Afterwards, they were sent to Liu He Tong Company in Beijing for nucleotide sequencing. Finally, phylogenetic analysis of the sequencing data was performed with MegAlign (Version 1.03) and Editseq (Version 3.69) software.


RESULTS
The genomic characterizations of A/Swine/Shandong /5/2002(H9N2) and A/Swine/Shandong/10/2002(H9N2) viruses were different from those of H9N2 viruses which were isolated either from men or from chickens. The genomic characteristics of H9N2 viruses isolated from humans in China mainland were similar to those of H9N2 viruses isolated from chickens. Whereas, the genomes of H9N2 viruses isolated from men in Hong Kong, China were closely related to those of H9N2 viruses isolated from quails. Avian influenza A H9N2 viruses not only have wide range of host, but their genomes are also diverse.


CONCLUSIONS
Avian influenza A H9N2 viruses can directly infect human. Avian influenza A H9N2 viruses did not require to pass through the pigs as mixing vessels prior to infecting man.
Guo
Yuan-ji
YJ
Research Laboratory of Influenza, Institute of Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100052, China.
Wen
Le-ying
LY
Zhang
Ye
Y
Wan
Min
M
Guo
Jun-feng
JF
Li
Zi
Z
Shu
Yue-long
YL
D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens / Q000821:virology; D002681:China; D010856:Columbidae / Q000821:virology; D006389:Hemagglutinins, Viral / Q000235:genetics; D006801:Humans; D053127:Influenza A Virus, H9N2 Subtype / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D005585:Influenza in Birds / Q000821:virology; D007251:Influenza, Human / Q000821:virology*; D019590:Nucleocapsid Proteins; D009976:Orthomyxoviridae Infections / Q000821:virology*; D010802:Phylogeny; D012367:RNA, Viral / Q000302:isolation & purification; D016601:RNA-Binding Proteins / Q000235:genetics; D013552:Swine / Q000821:virology*; D014758:Viral Core Proteins / Q000235:genetics; D014763:Viral Matrix Proteins / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000235:genetics
D006389:Hemagglutinins, Viral; C048842:NP protein, Influenza A virus; C108309:NS protein, influenza virus; D019590:Nucleocapsid Proteins; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D014758:Viral Core Proteins; D014763:Viral Matrix Proteins; D017361:Viral Nonstructural Proteins