%0 Journal Article
%T A single-amino-acid substitution in the HA protein changes the replication and pathogenicity of the 2009 pandemic A (H1N1) influenza viruses in vitro and in vivo
%A Lili Xu
%A Linlin Bao
%A Qi Lv
%A Wei Deng
%A Yila Ma
%A Fengdi Li
%A Lingjun Zhan
%A Hua Zhu
%A Chunmei Ma
%A Chuan Qin
%J Virology Journal
%D 2010
%I BioMed Central
%R 10.1186/1743-422x-7-325
%X Here, we found that a single amino acid substitution of Asp-to-Gly at position 222 in the HA protein of the A (H1N1) virus occurred after two passage propagation in the allantoic cavities of chicken embryonated eggs, and this single residue variation dramatically increased the viral replication ability in MDCK cells and pathogenicity in BALB/c mice.A substitution of Asp-to-Gly at position 222 in the HA protein was prone to occur under positive selection pressures, and this single amino acid mutation could dramatically increase the virus replication ability in vitro and pathogenicity in vivo. Our finding offers a better understanding of the transmission and evolution of the 2009 pandemic A (H1N1) virus and brings attention to further potentially severe influenza pandemic that may result from cross-host evolution of the influenza viruses.On June 11, 2009, the World Health Organization raised the global pandemic alert level to phase 6, the pandemic phase, in response to the emergence and global spread of a novel A (H1N1) influenza virus, which emerged in Mexico in early 2009 [1]. The onset of the pandemic A (H1N1) influenza virus infection has been relatively mild, with clinical manifestations progressing from mild upper respiratory tract illness to severe pneumonia leading to acute respiratory distress syndrome [2]. Sporadic deaths happened in individuals with poor pre-existing immunity to influenza viruses. However, it is projected that mutations in the viral genome could result in more virulent viruses, leading to a more severe pandemic.The virulence, pathogenicity, and host range of influenza viruses are determined by many factors, including virus-specific determinants encoded within the viral genome. The HA protein is especially important in that it main functions were receptor binding and membrane fusion. Glaser et al. reported that a single amino acid mutation at position 190 of the HA protein of the 1918 pandemic H1N1 influenza virus resulted in a preference fo
%U http://www.virologyj.com/content/7/1/325