| An H5N1 swine influenza virus named A/Swine/Fujian/F1/01(H5N1) was firstly isolated from Fujian province of China in 2001. To understand the molecular evolution and biological characteristic of this virus, the entire genomes of this virus was completely sequenced and compared to those of H5N1 influenza viruses isolated from mainland China and Southeast Asia. Also in this study, we established the reverse genetic system of this virus.Phylogenic analysis showed that all eight gene segments of this H5N1 swine influenza virus originated from avian influenza viruses. All gene segments were most closely related with A/Duck/Zhejiang/52/00(H5N1), the nucleotide and amino acid sequences homologies were greater than 99.3%. The homology of A/Swine/Fujian/F1/01(H5N1) and human influenza viruses—HK/483/97,HK/486/97 were less closer than that of HK/213/03. Sequence comparison of part of internal gene segments from this virus and the influenza viruses that were isolated from Southeast Asian human, cat and tiger showed greater than 98.8% sequence identity between them.This swine influenza virus was highly pathogenic for specific-pathogen-free (SPF) chickens. The intravenous pathogenicity index (IVPI) and mean death time (MDT) to chicken was 2.52 and 2.4 days respectively. The virus had a broad tissue tropism after intranasal inoculation it can cause sever systemic disease in multiple organs and the brain. The titer of virus isolated from lung, liver and pancreas were higher than that of other organs, such as cardiac muscle, spleen, brain, kidney, Fabricius bursa. This study indicated that the swine influenza virus A/Swine/Fujian/F1/01(H5N1) retained its high lethality for chickens.This study revealed the genetic relationship between swine influenza virus A/Swine/Fujian/F1/01 (H5N1) and other H5N1 isolates, thus provided data for the genetic analysis of swine influenza virus H5N1 subtype in China. Meanwhile, the study established the reverse genetics system of SIV A/Swine/Fujian/F1/01(H5N1) and rescued the virus successfully by in vitro transfection. This work settled a solid base for the further research of pathogenicity mechanism, structure and functions of H5N1 SIV and the development of novel vaccine in future. |
