Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, PR China.
Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS 66506, USA.
J Gen Virol. 2012 Nov;93(Pt 11):2337-2345. doi: 10.1099/vir.0.044040-0. Epub 2012 Aug 8.
Both H9N2 avian influenza and 2009 pandemic H1N1 viruses (pH1N1) are able to infect humans and swine, which has raised concerns that novel reassortant H9 viruses with pH1N1 genes might be generated in these hosts by reassortment. Although previous studies have demonstrated that reassortant H9 viruses with pH1N1 genes show increased virulence in mice and transmissibility in ferrets, the virulence and transmissibility of reassortant H9 viruses in natural hosts such as chickens and swine remain unknown. This study generated two reassortant H9 viruses (H9N2/CA09 and H9N1/CA09) in the background of the pH1N1 A/California/04/2009 (CA09) virus by replacing either both the haemagglutinin (HA) and neuraminidase (NA) genes or only the HA gene with the respective genes from the A/quail/Hong Kong/G1/1997 (H9N2) virus and evaluated their replication, pathogenicity and transmission in chickens and pigs compared with the parental viruses. Chickens that were infected with the parental H9N2 and reassortant H9 viruses seroconverted. The parental H9N2 and reassortant H9N2/CA09 viruses were transmitted to sentinel chickens, but H9N1/CA09 virus was not. The parental H9N2 replicated poorly and was not transmitted in pigs, whereas both H9N2/CA09 and H9N1/CA09 viruses replicated and were transmitted efficiently in pigs, similar to the pH1N1 virus. These results demonstrated that reassortant H9 viruses with pH1N1 genes show enhanced replication and transmissibility in pigs compared with the parental H9N2 virus, indicating that they may pose a threat for humans if such reassortants arise in swine.
H9N2 禽流感病毒和 2009 年大流行的 H1N1 病毒（pH1N1）均能感染人类和猪，这引发了人们的担忧，即这些宿主中可能通过重配产生具有 pH1N1 基因的新型重配 H9 病毒。尽管先前的研究表明，具有 pH1N1 基因的重配 H9 病毒在小鼠中显示出更高的毒力和在雪貂中更高的传染性，但在鸡和猪等自然宿主中重配 H9 病毒的毒力和传染性仍不清楚。本研究通过用来自 A/quail/Hong Kong/G1/1997（H9N2）病毒的相应基因替换 pH1N1 A/California/04/2009（CA09）病毒的血凝素（HA）和神经氨酸酶（NA）基因或仅 HA 基因，生成了两种重配 H9 病毒（H9N2/CA09 和 H9N1/CA09），并评估了它们与亲本病毒相比在鸡和猪中的复制、致病性和传播情况。感染亲本 H9N2 和重配 H9 病毒的鸡血清转化。亲本 H9N2 和重配 H9N2/CA09 病毒传播到哨兵鸡，但 H9N1/CA09 病毒未传播。亲本 H9N2 在猪中复制能力差且不能传播，而 H9N2/CA09 和 H9N1/CA09 病毒在猪中高效复制和传播，类似于 pH1N1 病毒。这些结果表明，与亲本 H9N2 病毒相比，具有 pH1N1 基因的重配 H9 病毒在猪中显示出增强的复制和传播能力，表明如果此类重配在猪中出现，它们可能对人类构成威胁。
