基于PRRSV灭活疫苗免疫的PRRSV类NADC30株防控案例分析

Case analysis on the prevention and control of PRRSV NADC30-like based on PRRSV inactivated vaccine

2018年1月份广西玉林某猪场母猪出现大规模流产,初生仔猪腹股沟淋巴结发青、发紫,死亡率达到15%以上;保育猪在断奶后1周开始发烧,呼吸道症状明显,死亡率高达20%。为了对该猪场猪只所患疾病进行诊断,试验采用RT-PCR方法确定感染病原并对其进行遗传进化分析,根据诊断结果制订和实施了疫苗免疫和药物治疗方案,通过统计猪场发病前后6个月的生产性能指标(窝均产仔数、窝均产健仔数、产房仔猪死亡率、保育仔猪死亡率)和采用荧光RT-PCR方法对母猪血清中的病原和抗体进行监测,评价综合防控方案的效果。结果表明:引起该猪场母猪繁殖障碍的病原为猪繁殖与呼吸综合征病毒(PRRSV),对其ORF5和Nsp2基因测序,测序毒株命名为GXYL 2018,该毒株与PRRSV NADC302012株在同一进化分支上,基因相似性分别为91.7%和90.6%。采用PRRSV灭活疫苗免疫和药物治疗方案后,该猪场母猪繁殖障碍症状消失,经产母猪、后备母猪和公猪血清中PRRSV阳性率和抗体离散度分别下降了64.16,48.19,80.00百分点和38.43,14.76,23.97百分点;母猪窝均产健仔数增加了1.61头,产房和保育仔猪死亡率分别下降了9.72,10.02百分点。说明PRRSV灭活疫苗免疫和药物治疗方案可以用于PRRSV类NADC30株引起的母猪繁殖障碍的综合防控。

In January 2018,a large-scale abortion occurred in sows in a pig farm in Yulin region,Guangxi Province.The inguinal lymph nodes of newborn piglets turned blue and purple,and the mortality rate reached more than 15%;nursery pigs began to develop fever one week after weaning,with obvious respiratory symptoms and high mortality 20%.In order to diagnose the disease of pigs on the pig farm,the experiment used RT-PCR to determine the pathogen of the infection and analyze its genetic evolution.Based on the diagnosis results,a vaccine immunization and drug treatment plan was formulated and implemented.The effect of the comprehensive prevention and control program was evaluated by the production performance indicators(such as the number of litters within 6 months,average litter size per litter,average healthy litter size per litter,piglet mortality rate in delivery room,and morlality rate of mursery piglets),monitoring the PRRSV pathogen by fluorescent RT-PCR methods,and antibodies in the sow’s serum.The results showed that the pathogen causing reproductive disorders in sows on the farm was PRRSV.Sequencing and genetic evolution analysis of its ORF5 and Nsp2 genes,the sequencing strain was named GXYL 2018,the virus strain and the PRRSV NADC302012 strain were on the same evolutionary branch,and the qenetic similarity was 91.7%and 90.6%respectively.After immunization with PRRSV inactivated vaccine and drug treatment programs,sows in the farm showed no symptoms of reproductive disorders.The PRRSV positive rates and antibody dispersion in the serum of sows,gilts and boars decreased by 64.16,48.19,80.00 percentage points,and 38.43,14.76,23.97 percentage points respectively.The number of healthy litters per sow litter increased by 1.61,and the mortality rates of farrowing room and nursery decreased by 9.72 and 10.02 percentage points respectively.The results suggested that PRRSV inactivated vaccine immunization and drug treatment can be used for the comprehensive prevention and control of sow reproductive disorders caused by PRRSV NADC30-like strain.