| Porcine reproductive and respiratory syndrome(PRRS)is a highly contagious disease of pigs caused by PRRSV,which mainly causes reproductive disorder of sows and acute morbidity and mortality of piglets.It is harmful to the pig industry and causes incalculable economic losses.In recent years,frequent blue-ear disease,each region to the region of PRRSV,popular and genetic variation of the virus,immune to this test in each parts of pig serum and spleen and pathogen serum epidemiology investigation,and at the same time analyze the strain of GP5 gene sequences,pig farms in each area provides the theory basis for better prevention PRRS,will now this test results summarized as follows:1.In 2018-2019,45 sows serum and 307 piglets serum were collected from two unimmunized pig farms in sichuan and chongqing,and the results were detected by ELISA.The results showed that 37 sows were positive,with a positive rate of 82.22%,and 219 piglets were positive,with a positive rate of 71.34%.The difference of positive rate between sows and piglets was significant(P<0.5).Of the 18 sows serum samples from lufeng pig farm in yibin,sichuan,12 were positive,with a positive rate of 66.67%,and 25 were positive,with a positive rate of 92.59%,from the 27 sows serum samples from xianyin pig farm in liangpingzhou,chongqing.After statistical analysis,the positive rate of PRRSV in sows of two pig farms was significantly different(P<0.5).Sichuan luzhou light silver pig farms,sichuan luzhou radically pig farms,sichuan yibin green abundant pig farms,sichuan yibin zhang SAN pig farms,chongqing Liang Pingzhou xian silver pig farms,chongqing LiangPingxu his pig,the state order crystal pig,chongqing state auspicious pig eight pigs piglet PRRSV positive rate were 44.12%,44.44%,66.00%,62.50%,91.49%,88.64%,86.67%,85.42%,72.73%,after statistics analysis,luzhou light silver pig farms and luzhou radically pig PRRSV positive difference was not significant(P > 0.05),There was no significant difference in the positive rate of PRRSV between chongqing liangpingxu benbin pig farm and chongqing kaizhou zhongshi pig farm(P > 0.05),and there was a significant difference in the positive rate between other large-scale pig farms(P < 0.05).The results showed that the infection rate of PRRSV in large-scale pig farms in sichuan and chongqing was significantly different,with the lowest rate of 44.12% and the highest rate of 91.49%,which should be attached great importance to the farms.2.Statistics of the S/P value of PRRS antibody showed that: Sichuan luzhou light silver pig between 0.01 ~ 0.55,sichuan luzhou radical farm between 0.03 ~ 0.48,sichuan yibin green abundant farm between 0.01 ~ 0.83,sichuan yibin zhang SAN pig farms in between0.04 ~ 0.76,chongqing Liang Pingzhou xian silver pig farms in between 0.03 ~ 1.18,the chongqing Liang Pingxu this pig between 0.03 ~ 1.09,chongqing state order pig,chongqing state between 0.03 ~ 0.68 crystal auspicious pig between 0.01 ~ 0.86,according to the results are not more than 2.0 and above,All eight pig farms were PRRS stable.3.29 spleens of suspected diseased pigs were collected from some pig farms in sichuan and chongqing region(including 12 in luzhou,5 in yibin,4 in yongchuan and 8 in kaizhou),and specific primers were designed based on GP5 gene for rt-pcr detection.The results showed that: the positive rate was 31.03% in 9 cases,including 1 case in luzhou and 2 cases in yibin,sichuan,and the positive rate in sichuan was 17.65%.The positive rate in chongqing was 50.00%,with 2 in yongchuan and 4 in kaizhou.PRRSV was detected in sichuan and chongqing,but the detection rate in chongqing was significantly higher than that in sichuan,which should be attached great importance to large-scale pig farms in chongqing.4,selection of sichuan yibin(YB-1,YB-2),chongqing yongchuan(YC-4),chongqing kaizhou(KZ-1,KZ-2,KZ-3),representative 6 strains of the disease,such as virus,ORF5 gene sequencing and comparison of 6 strains of disease material between homologous strains in82.6% ~ 99.0%,including yongchuan positie disease material strain(YC-4)and open state positive material strain(KZ-1)the highest homology,99.0%;The homology between kz-2and kz-3 of kaizhou was the lowest(82.6%).The homology of ORF5 gene was83.6%~98.8%,83.4%~99.7%,81.0%~84.6%,83.3%~94.5%,83.9%~89.7%,83.8%~94.5%,respectively.The homology of ORF5 gene was significantly different,indicating that the 6strains of positive pathogen virus had undergone different degrees of variation,and had higher homology with the commonly used vaccine strains JAX1 and HUN4 in China.Some strains(such as KZ-1 and YC-4)have more than 99% homology,and the vaccine prepared by domestic JAX1 and HUN4 strains has a good immune effect.Except for kz-2,the homology of var-2332 and MLV was lower than 90%,indicating that the immune effect of foreign PRRSV vaccine was not necessarily good.Will 6 strains of virus positive epidemic materials and 12 strains of evolutionary tree reference strains drawing system at home and abroad,found,KZ-3,KZ-1,YB-2,YC-4,YB-1are belong to the same big teams,KZ-2 with other disease strains is not in the same group of evolution,including the rest 5 strains of disease except KZ-2 material and the main highly pathogenic virus vaccine strains JXA1 close relatives,suggests that this material 5 strains of disease virus may be evolved by JXA1 variation.It is suggested that when the blue ear disease is controlled in pig farms in sichuan and chongqing,the live seedlings produced with JXA1 strain will produce better immune effect. |
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