Epidemiological Investigation Of PRRS In Jinhua City And Studies On Immunological Enhancement Of IRPS On PRRS Vaccine

Porcine reproductive and respiratory syndrome(PRRS) is a new type of infectious disease of pigs caused by the porcine reproductive and respiratory syndrome virus (PRRSV), with clinical manifestations of continuous high fever (body temperature of 41-42℃), anorexia, dyspnea, lethargy, high propagation velocity, resulting in huge economic losses. In this study, clinical symptoms, epidemiology and etiological agents of some PRRS positive farm were investigated in Jinhua area. The results indicate that PRRS was widespread among every process of production in Jinhua area.In order to effectively control the PRRS, this study carried out the following work:The PRRS epidemiology was investigated in Jinhua.The results showed that the incidence of some farms up to 60%, mortality rate of 89.29%.The mortality rate of piglet could reach almost 100%. PRRSV and PCV2 were detected in Several pig farms by PCR.Carry out toxicity test of IRPS. Radix isatidis is cold-natured and bitter in taste, which have effect of heat-clearing and detoxicating, blood cooling and detumescence. IRPS have more content and immunocompetence with a function of enhancing immunity and anti-virus. Toxicity test and immunity test were carried out in this study, validating the immunity enhancement effect of IRPS, which provided theoretical basis for screening immunoenhancer of PRRSV vaccines.30 mice were selected and divided into six groups, different polysaccharide concentrations were set. Feed two weeks after intraperitoneal inject 2 mL of different concentrations of IRPS. All mice survived after injection, no hemorrhage and hyperemia were observed on heart, liver and kidney. RBC was normal. WBC changed under significant difference. The results indicated that among this concentration range, IRPS have no obviously adverse effect on organism. 18 healthy Landrace crossbred piglets were selected, randomly divided into 3 groups of Group control, groupⅠ, and groupⅡ. Group I were injected of PRRS vaccine, groupⅡwere injected IPRS besides PRRS vaccine. Then each pig was inoculated with 2.0 mL PRRS virus. The results indicate associating PRRS vaccine with IRPS could increase antibody level against PRRSV and significantly reduce PRRS morbidity and mortality.