Identification And Isolation Of Porcine Reproductive And Respiratory Syndrome Virus And The Epidemiology Investigation Of Zhumadian

Isolation and identification of suspicious Porcine Reproductive and Respiratory Syndrome (PRRS) virus is researched on zhumadian city pig farms to understand the type of strain。This investigation provides the reference to prevent and control the epidemic Porcine Reproductive and Respiratory Syndrome in Zhumadian area。Material is gathered from sick pigs in Zhumadian pig farms。Indirect immunity fluorescence experiment(HF) and reverses transcription-the polymerase chain reaction(RT-PCR) are carried out。By primers of PRRSV ORF7 gene,we isolate and identify the PRRSV viruses,We've obtained 1 PRRSV named PRRSV Hnz-1/08 belonging to the American type。Epidemiology investigation is carried out using established reverses transcription-the polymerase chain reaction in zhumadian。311 suspicious sick pig samples from 160 pig farms in 10 counties and districts are examined for postive/negative test。146 PRRSV positive samples are detected(sample positive rate is 46.9%)。They come from 81 pig farms(pig farm PRRSV infection rate is 50.6%)。The 2006-2008 PRRSV positive rates were 52.8%,47.2%,42.3% respectively。It shows that PRRSV is common in zhumadian。The large-scale epidemic PRRS has brought enormous economic losses to pig-raising industry。We have a detailed understanding of the pathogenesis of the disease,clinical and pathological changes in the process of diagnosis。The main symptoms of sick pigs are respiratory symptoms for piglets,or sow reproductive obstacles - piglets respiratory symptoms。PRRS occurs mainly in piglets younger than 30-day-old and 30 to 60-day-old pigs and sows。Meanwhile there is a certain percentage of incidence to sows。The main reason is probably because piglets have no established immune system and thus low immunity。PRRS infection invades the alveolar macrophages,damages the immune system of pigs,leading to the PRRSV high infection rate and high morbidity in piglets。As a respiratory disease,PRRS is impacted by seasonal changes。It mainly occurs in autumn and winter。After we understand the prevalence and trends in a certain region,we can take specific measures to decrease the spread of PRRS and to reduce the losses caused by PRRS。...