Virulence And Replication Of H5N1 Avian Influenza Viruses In Domestic Ducks

Ducks are regarded as the natural reservoir of influenza viruses, and previous studies indicated that the avian influenza viruses could replicate in the digestive tract of ducks and shed through cloaca without causing any disease signs in these animals. However, H5N1 influenza viruses have caused multiple disease outbreaks in ducks in recent years. To evaluate the virulence of the H5N1 influenza viruses in the experimental set, we tested 7 H5N1 viruses in special pathogen free (SPF) ducks. We found 4 out of the 7 viruses are highly pathogenic for ducks, and these viruses killed 100% of the inoculated ducks within 7 days. Two viruses killed partial of the inoculated ducks, while one virus, A/Goose/Hubei/65/05 (GS/HB/65/05), did not induce any disease signs or kill any of the ducks inoculated. We further found that, though it is non-pathogenic to ducks, the GS/HB/65/05 replicates systemically in ducks, and the inoculated ducks also shed the virus through both larynx and cloaca. Detailed studies of these viruses will provide an insight on the genetic basis of the virulence of H5N1 influenza viruses in ducks.The researchers on level of genes have gained a lot, but proteins perform function, so for the purpose of better knowing pathogenesis and host restrictions determinants, we should learn more about proteins. We here make use of pcDNA3.1 and C\N-terminal Mammalian TAP Vectors to constitute two plasmids, which can express polymerase complex and NP proteins of AI virus (DK/HB/49/05) in eukaryotic cells. Then we perform nine groups of DNA transfections in 293T cells, harvest cells and catalyze bioluminescent reactions by Firefly and Renilla luciferases. And we find that in 293T cells the activity of polymerase with TAP tag all descend: C-TAP-PB1 and C-TAP-NP proteins make polymerase activity descend about 10%; C-TAP-PA, N-TAP-PB2 and N-TAP-NP proteins, about 70%; and C-TAP-PB2, N-TAP-PA, N-TAP-PB1, about 90%.