| The dominate influenza viruses circulating in human were H1N1and H3N2influenza virus. The coexistence of seasonal H1N1and pandemic H1N1influenza virus provides an opportunity for these viruses to reassert. The ressortment may be generated a novel high pathogenicity virus, which case a threat to the public health.To evaluate the potential public risk of the reassortant viruses derived from these virus, we used reverse genetics to generated3reassortant virus derived from the2009H1N1pandemic and seasonal influenza virus and characterized pathogenecity of the reassortant virus. First, we constructed the8plasmids system of the2009H1N1influenza virus with reverse genetic by cloned the influenza viral cDNA into the vector of PHW2000which contained poll-polll of bidirection transcriptional expressing system. Since the hemagglutinin and neuraminidase were the main antigenic glycoprogeins of the influenza virus and which posed an important role to the pathogenicity of the influenza virus, so we generate3reassortants which co-expressing the HA and NA or expressing the individual genes of HA or NA from the2009pandemic H1N1virus.Then the biocharacteristics of the reassortants in vitro were observed. The viruses titer, plaques, growth curve of the reassortants were performed on MDCK cells, the replication ability of the reassort virus co-expressing the HA and NA of the2009pandemic H1N1influenza virus was similar to the parental wild influenza virus while the reassort virus expessing the HA or NA of the2009pandemic H1N1influenza virus were attenuated on MDCK cells compared to the parental wild influenza virus.To characterize the pathogenicity of the ressortant virus, mice were intratracheally infected with the reassort virus and the median lethal dose (MLD50) and median infection dose (MID50) of the reassort virus in BALB/c mice were evaluated. The weight loss, lung index and lung virus loads in the infected mice were also investigated. The mice lung virus titer infected with the reassort virus co-expressing the HA and NA or expressing the individual genes of HA of the2009pandemic H1N1influenza virus were significantly higher than those infected with the parental wild influenza virus, while the median lethal dose (MLD50) and median infection dose (MID50) of the reassort virus in BALB/c mice were lower than the parental wild influenza virus. The severe lesions in the mice lung tissues which were infected with the reassort virus were analyzed. The date showed that the reassort virus co-expressing the HA and NA or expressing the individual genes of HA of the2009pandemic H1N1influenza virus were increased pathogenicity in BALB/c mice, revealing the important role of the HA gene from the2009pandemic H1N1influenza in the pathogenicity of the reassort virus.Our study suggested that pandemic H1N1virus has the potential to reassort with seasonal H1N1viruses, and the reassort influenza virus may result in increased pathogenicity which were managed by the HA of the2009pandemic H1N1influenza virus. Our results indicate that seasonal-pandemic reassortants could increase the pathogenicity of the virus that may be posed a threat for human health. At the same time, the reassort virus laid the foundation for the exploring of the pathogenic machanism of the reassortment, especially the functions of HA. |
