The Pathhgen Detection Of "Swine High Fever Syndrome" And Gene Analysis Of The Partial Nsp2 And Complete ORF5 Of PRRSV Of Guangxi

"swine high fever syndrome" first broke out in Jiangxi,Hunan and other places in China in May 2006,with the symptom of high fever,breathing difficulties and acute death,The disease propagate swift,powerful,mostly mixed infection,and hadn't specific control methods to identify the pathogen of the "swine high fever syndrome" of Guangxi,we detected the pathogen of porcine reproductive and respiratory syndrome virus(PRRSV),classical swine fever virus(CSFV),swine pseudorabies virus(PRV), porcine circovirus type 2(PCV-2),swine influenza virus(SIV),Haemophilus parasuis (HPS),such as several common bacterial and virus of pig disease form 13 cities of Guangxi.The result showed that the highest detection rate of PRRSV mutant strain was that up to 54.23 percent,followed by PCV 38.85%,CSFV 28.1%,SIV 10.38%,PRV and HPS were 2.69 percent respectively.We could know that the main pathogenic of "swine high fever syndrome" in Guangxi was PRRSV mutant strain,PCV and CSFV played an important role.The mixed infection of PRRSV and other pathogens was very serious,dual infection(PRRSV+ CSFV,PRRSV+ PCV,PRRSV+ SIV,PRRSV + PRV, PRRSV+ HPS) as high as 43.08 percent,triplinfections(PRRSV + CSFV + PCV,PRRSV + CSFV + SIV,PRRSV + PCV + SIV) accounted for 20.97 percent.The most mixed infected up to four types of re-infection(PRRSV+ CSFV + PCV + SIV).In the mixed infection of the pathogen,the PRRSV+PCV,PRRSV+ CSFV were the highest infection rate,respectively 21.2 percent and 18.43 percent.We cloned the partial Nsp2 of 16 strains of PRRSV mutant strain form 13 City of Guangxi,gene analysis show that the PRRSV mutant strains of Guangxi were exactly the same characteristics as other provinces,that was,482 and 534 to 562 amino of Nsp2 were absent.the sequence homology of the Guangxi PRRSV mutation strains was 90.2%to 99.2%,with a similarity of 90.0%to 99.7%in deduced amino acid sequence.The sequence homology of the Guangxi PRRSV mutation strains and other provinces was 90.2%to 99.2%,and with a similarity of 78.0%to 100%in deduced amino acid sequence.The complete ORF5 gene of 6 strains of PRRSV were cloned and gene analysised. The results showed that ORF5 was the size of 603 bp.And they ware high homology with the North American genotype,the sequence homology was 94.7%to 98.7%,with a similarity of 88.0%to 99.5%in deduced amino acid sequence,but only 53.2%to 59.8% with the LV strains.Antigen analysis of ORF5 gene showed that the 6 strains of Guangxi were very similar with JXA1,LN,GD,HUB2,HEB1,and other PRRSV mutant strains,only 192 to 200 amino acids were slight differences.The 6 strains had the same amino acid epitope sites with other PRRSV strain in 35 to 41,53 to 60,131 from 145,151 to 159,163 to 191,193 to 200.And there was no significant difference in Epitope advantage.