Isolation and genetic characterization of avian origin H9N2 influenza viruses from pigs in China.
As pigs are susceptible to infection with both avian and human influenza A viruses, they have been proposed to be an intermediate host for the adaptation of avian influenza viruses to humans. In April 2006, a disease caused by highly pathogenic porcine reproductive and respiratory syndrome virus (PRRSV) occurred in several pig farms and subsequently overwhelmed almost half of China with more than 2,000,000 cases of pig infection. Here we report a case in which four swine H9N2 influenza viruses were isolated from pigs infected by highly pathogenic PRRSVs in Guangxi province in China. All the eight gene segments of the four swine H9N2 viruses are highly homologous to A/Pigeon/Nanchang/2-0461/00 (H9N2) or A/Wild Duck/Nanchang/2-0480/00 (H9N2). Phylogenetic analyses of eight genes show that the swine H9N2 influenza viruses are of avian origin and may be the descendants of A/Duck/Hong Kong/Y280/97-like viruses. Molecular analysis of the HA gene indicates that our H9N2 isolates might have high-affinity binding to the alpha2,6-NeuAcGal receptor found in human cells. In conclusion, our finding provides further evidence about the interspecies transmission of avian influenza viruses to pigs and emphasizes the importance of reinforcing swine influenza virus (SIV) surveillance, especially after the emergence of highly pathogenic PRRSVs in pigs in China.
Yu
Hai
H
National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, China.
Hua
Rong-Hong
RH
Wei
Tian-Chao
TC
Zhou
Yan-Jun
YJ
Tian
Zhi-Jun
ZJ
Li
Guo-Xin
GX
Liu
Tian-Qiang
TQ
Tong
Guang-Zhi
GZ
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks / Q000662:veterinary; D006801:Humans; D053127:Influenza A Virus, H9N2 Subtype / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D008969:Molecular Sequence Data; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000635:transmission / Q000821:virology*; D015047:Zoonoses