Lsolation And Ldentification Of Porcine Reprodictive And Respiratory Syndrome(PRRS) Pthogen And Study On Their Prevemtive Mesures

In this study, we isolated and identified the suspected PRRSV infected materials collected from different regions of Henan province and around regions,then analyzed genetic variation levels. Based on the survey results of PRRS epidemiological of Henan province, we suggested the prevention and control of PRRS with vaccination by live attenuated vaccine and treatment with chinese herbal medicine preparations and anti-PRRSV immune serum resulting in a simple,effective and practical measure for preventing and controling PRRS that can improve production level of swine industry.1. We collected about 180 suspected samples from partial areas in Henan and Hubei province during 2006-2013, ten PRRSV strains were gained in culture Marc-145 cell. Among the isolated PRRSV strains, nine strains was isolated from Henan province, one strain was isolated from Xiangfan City in Hubei province. The fragment of Nsp2 and ORF5-7 genes that from isolated PRRSV strains were cloned into plasmid pMD-18 T vectors and sequenced. The phylogenetic analyses showed that all the isolated strains were America-type PRRSV strains and Nsp2 gene had part deleted. However, GP5 gene did only locus mutated not for deletion.HeN1-06 strain and ATCCVR-2332 strain are in the same evolutionary branch, the others(HeN2-06,HeN3-06,HeN1-07,HeN2-07,HeN3-07,HeN1-08,HeN2-08,HeN3-08,HeN4-08) are in the other evolutionary branch with CH-1a strain. These results confirmed that PRRSV from Henan province were variability and based on highly pathogenic strain.2. PRRS maternal antibody fluctuation rule tests showed that the value of S/P and duration of antibodies were positively correlated with blood and colostrum antibody, and value of S/P of maternal antibody in piglets began to decline at 14 days old, and 38 days old was reduced to the lowest level, and the average half-life was12 days. So we made the immunization programs that the first immunization forpiglets was implemented at 21 day and then conducted the second immunization interval at 45 day, respectively, following 1 dose once. The immune plan that parent stocks were immuned three times every year and double dose once is worked.3. This study used three kernel soup compound preparation effected on Marc-145 cells. We determined and analyzed the CPE of Marc-145 cells infected with PRRSV that were fouced on the virus adsorption blocking effects, the copy inhibition of proliferation of direct inactivation of virus inactivation and direct kill of the virus. The results showed that three kernel soup compound preparation had significant inactivated, inhibition and blocking effect. To PRRSV directly inactivated of the minimum mass concentration is 15.625 g/L,inhibition of the minimum mass concentration is 31.25 g/L, to PRRSV blocking of the minimum mass concentration is 125 g/L.4. Prevention and control of PRRS using the above immunization programs in pigs production, we found that the farrowing rate could improve 13.9% which increased from 76.6% to 90.5%, the survival rate of nursery pigs increased from89% to 98%, improved 9% and the survival rate of finishing pigs increased from87% to 95%, improved 8%. Three kernel soup compound preparation could prevent and treat swine PRRS remarkably, the result of the 1825 incidence of conservation pig treatment survival rate could reach 99.28%, compared with the single antibiotic to secondary infections, the survival rate improved 17.18% with daily gain improved80 g/d. Following, the farrowing rate improved 39.8% and the newborn piglets healthy seed rate improved 53.2% while 8994 results fattening treat high survival rate reached 95.73%. Using 1ml per kilogram of body weight anti-PRRSV hyperimmune serum to muscle inject nursery pig infected at early period could improve 10.32% within the rate of survival increase from 86.56% to 96.85%.In summary, this study demonstrated that the PRRSV strains infection and prevalence in Henan province were quite universal and strains variation were widespread. Using PRRSV live attenuated vaccine, three kernel soup compound preparation and anti-PRRSV immune serum together to control and treat PRRSVclinical symptoms produces significant results, which decreased the abortion rate of sows and the mortality of piglets, which further improved and enhanced clinical manifestation of pigs resulting in increasing production level of swine industry.