Serological And Molecular Epidemiology Of Porcine Reproductive And Respiratory Syndrome In Anhui

In 2006,the high pathogenic PRRSV has caused great economic losses to the pig industry in our country.PRRSV genome prone to variation,and the GP5 protein is the most significant structural protein.Through the comparison and analysis of the cloning and expression of PRRSV GP5 protein in Anhui Province in recent years,it has great significance to understand the variation of the protein.First of all,survey investigation and molecular epidemiology of serum during the period from September 2015 to October 2014 through to some areas of Anhui province PRRSV suspected swine,collect serum of the without PRRS vaccine immune serum,antibody detection by ELISA.Survey shows,71 serum samples collected from 44 pig farms were detected 33 positive sera,the detection rate was 46.48%,the positive rate of swine was 40.91%.With more than 500 large-scale pig farms in the field of higher detection rate reached 50%,disease of swine serum samples 100 the following scale detection rate of up to 69.57%.Different ages of pigs were infected with PRRS,with more than 2 months weighing about 100 pounds in the herd incidence rate was the highest.The results show that the natural infection in swine in Anhui province PRRS.Then on October 2014 to September 2015 13 in Anhui Province,a total of 119 suspected cases of swine,211 suspected cases were detected by RT-PCR in laboratory,the positive case detection were observed clinical symptoms and anatomic pathological changes,and statistical analysis.44 of them are positive,the positive rate was 20.85%,the positive rate of pig farms was 25.21%.The results showed that the PRRSV infected pigs of each stage are able to infect,the suckling piglets and piglets mortality and morbidity rate highest,sows and finishing pigs.The main clinical features for sow miscarriage,stillbirth and mummy pig disease,temperature between 39.6 to 42 deg.After the data analysis can be found in the annual PRRS incidence,incidence and cause secondary infection and over two diseases affecting the pigs in the same time.The main pathological changes can be seen as interstitial pneumonia in lung.To collect typical disease material for the preparation of paraffin section and HE staining,pathological changes were observed under the microscope.Which significantly increased alveolar clearance,alveolar wall thickening,alveolar rupture to form a cavity,and small pulmonary bronchial intraluminal secretions,pseudostratified layer of columnar ciliated epithelium and ciliary epithelium showed the separation of cyclic isabout to fall off,there are large numbers of macrophages and lymphocytes infiltration,Histological observation results consistent with the macroscopic lesions.At last,further amplification and sequencing of the ORF5 gene in 16 samples of PRRSV were detected in RT-PCR positive disease.The homology comparison of ORF5 gene of 16 positive samples was found that,the similarity of nucleotide sequence between the ORF5 gene sequences of Anhui strains was 88.9%-100%,the similarity of the nucleotide sequence between the ORF5 sequences of Europe strains was59.4%-63.0%,nucleotide sequence similarity between JXA1,HUN4,TJ,and other highly pathogenic of America strains ORF5 PRRSV gene sequences 88.1%-98.5%.This result shows that the PRRSV strain of Anhui province is mainly belong to the American type.Comparison of epidemic strains in Anhui province and its neighboring provinces,results the similarity of nucleotide sequence between JS-B and JS/NT/2013(Shanghai)strain was 85.5%-99.3%,the similarity of nucleotide sequence of JXA1(Jiangxi)strain was 89.7%-99.7%,the similarity of nucleotide sequence of 06-JS-1 and 06-JS-2(Zhejiang)strain was 89.7%-99.3%.Construction of the genetic evolution tree can be seen in Anhui was found in 2006 after the strain of HP-PRRSV strains JXA1,HUN4,TJ and so on in the same branch,the homologous relation is close,may be from the same strain variation.Through protein amino acid sequence analysis,the 14 Anhui epidemic strains were found to highly homologous to the highly pathogenic PRRSV,while the other 2 were highly homologous to the classical PRRSV.To sum up,some pig farms of Anhui province at different stages of swine are natural infection.In the pathogenesis of swine clinical symptoms is not obvious,the highest mortality rate of nursery pigs.By histological observation and histopathological changes were observed under microscope and the macroscopic lesions consistent.Compared with the popular strains at home and abroad,it is found that the epidemic strains of Anhui province belong to the Americas,and with the highly pathogenic PRRS strains JXA1,HUN4,TJ and other similar,possibly by the same strain and variability.Through the investigation and analysis of prevalence of PRRSV in Anhui area,and provide experimental data for better prevention and control the disease.