Epidemiological Investigation Of Classical Swine Fever In Guangxi From2012to2013

Classical Swine Fever (CSF), one of the contagious infectious diseases, which caused by Classical Swine Fever Virus (CSFV), jeopardize pigs’health seriously and the economic benefits of pig industry. It is a pertinacious disease in Guangxi, continues to be one of the main diseases that cause great harm to the development of the swine industry. This study aimed to investigate the prevalence of CSF in Guangxi from2012to2013by using the IHA method to test on serum samples and RT-PCR detection on swine tissues which collected from Guangxi. Sequence analysis was then performed on the E2gene of nine positive strains by cloning and sequencing. Aim to understand the CSF epidemic in Guangxi from2012to2013, and provide a scientific basis for control and elimination of CSF in Guangxi.Serological studies showed that832(57.7%) of1443samples in2012and 1360(57.8%) of2353samples in2013were positive for CSF antibody. The results indicated that the average passing rate was57.7%, which was significantly lower. The RT-PCR test showed70(5.8%) of1212samples in2012and20(1.7%) of1161samples in2013were positive for CSFV antigens. The total positive rate was3.83%. During the two years, CSF has reduced gradually and occured all the year around in Guangxi, positive rate of CSFV in spring and autumn was higher than the other seasons. The stages of CSFV positive rate from big to small in turn are weaned pig, suckling pig, growing pigs and sows, respectively, CSFV infection is a priority to in weaned pig, the second was suckling pig, and it is observed that the infection tends to adolescent.E2Gene of the isolated strains from Guangxi were clone and sequenced,the nucleotide homology were81.3%～82.4%and81.9%～83.3%with Shimen strain and HCLV strain, respectively, while deduced amino acid homology for88.0%～89.6%and89.3%～89.6%, respectively. Key McAb recognized amino acid sites including G713E, H724Y, D725Q N729D, K734R, V738T, G761R et al. in E2of the isolated strains were changed. Phylogenetic analysis of E2gene showed the isolated strain were distributed in subgroup2.1, the GXYL1, GXYL2, GXYL3, GXYL4and GXYL5strain derived from subgroup2.1b,the GXHZ1, GXHZ2,GXBH1, GXBH2strain belonged to subgroup2.1c.