Isolation And Identification Of A Swine Transmissible Gastroenteritis Virus And Its Pathogenicity To Piglets

Transmissible gastroenteritis（TGE）is a highly contact enteric infectious disease caused by Transmissible gastroenteritis virus（TGEV）,which is characterized by diarrhea,vomiting and dehydration in piglets.It can infect pigs of all ages and caused a high mortality rate in suckling piglets.TGEV is spread by fecal and oral,which causes great harm to the pig industry.Therefore,the isolation strains can lay a material foundation for the epidemiological biological characteristics of the disease and as a backup strain for vaccine production.In this study,PK-15 cell monolayers were inoculated with the samples that were positive for TGEV.The cell cultures infected with TGEV were confirmed by CPE,RT-PCR,IFA and electron microscopy.Calculation of virus titer by TCID₅₀=10^-5.25/0.1 mL.In order to analyze the pathogenicity of TGEV HQ2016 strain.the TGEV HQ2016 strain virus solution was used to infect newborn piglet by oral administration for virus pathogenicity test.The results showed that the piglets in the challenge group developed diarrhea 12 h after infectionNo clinical signs were observed in the control group.The clinical symptom score of piglets in the challenge group was significantly different from that of the negative control group at 36 h of challenge.Piglets were euthanized at 84 h.The necropsy found that the intestinal wall of piglets in the challenge group became thinner.Fluorescence quantitative RT-PCR results showed that the nucleic acid of the virus was detected in the anus and intestine of the piglets in the challenge group.Histopathological examination showed that the jejunum ileum of the piglets had necrosis of intestinal epithelial cells,there are many inflammatory cells in the intestinal mucosa.Immunohistochemical observation showed that there were obvious positive signals in jejunum and ileum intestinal mucosal epithelial cells in the challenge group,there was no significant change in the control group.This study successfully isolated and identified a strain of transmissible gastroenteritis virus,The results of animal experiments showed that the strain was pathogenic to piglets.This study provides a preliminary basis for the future research on the pathogenic mechanism,vaccine strain screening and establishment of detection method of TGEV.