Epidemiological Investigation And Pathogen Analysis Of High-fever Syndrome

In May 2006,there was an outbreak of swine loimia,which the main characteristic was high fever.It was quickly spreaded and caused thousands death of swine.In July, this Ioimia occurred in Ningxiang County,Hunan Province.In order to investigate the epidemic and explore the pathogene,we carried out this experimental research.We visited the pig farm that broke out the disease and acquisited materials from typical swine;isolated,purified and identificated bacterias.The result shows this is a multi-pathogen disease,we can isolate several pathogenic bacterias from the swine catched the disease.We found some spherical and capsuled virus particles under the electronic microscope,which diameter is 60～100nm;through anti-body detection,nucleotide detection, and some other methods.We inferred that it would be caused by SIV or PRRSV.Through isolate and identity experiment on these two viruses,we precluded the SIV,and certained PRRSV was the main reason in the whole loimia.We isolated virus which make MARC-145 cells appeared CPE.We certained there was PRRSV in the sample by SN,RT-PCR ect.We extracted RNA,and amplificated gene ORF5 by PCR,sequenced gene ORF5 retrieved and compared with other ORF5 strains which published on Genebank,using DNASTAR to compare the homology and evolutionary relationship.We confirmed that the PRRSV we isolated are NA type by sequence analysis and serum experiment,the homology of gene ORF5 compared with the VR-2332 was 89.4%, and compared with other PRRSV strains which isolated by other researchers in the the other provinces in 2006 was 96.8%to 99.5%,among which the homology of separation strain in Jiangxi was the highest,reached 99.5%.By gene phylogenetic tree analysis,the two strains we separated and other PRRSV which isolated by other researchers were the same species.