| Porcine proliferative enteritis is characterized by adenomatous hyperplasia of immature intestinal epithelial cells in ileum and colonic crypts of piglets,as well as proliferation of intestinal mucosal epithelial cells and intestinal thickening of intestine,which be accompanied by diarrhea.Acute type is rare,but chronic and subclinical type are common in clinic,they were usually founded at slaughter eventually.The most obvious feature is the growth retardation of piglets,and the weight is much lighter than normal pigs.As the pathogenic bacterium of this disease,Lawsonia intracellularis is similar to campylobacter in morphology.The bacteria is rod-shaped,sharp or obtuse at both ends.The length is about 1.25~1.75?m,and the width is about 0.25~0.43 ?m,with three layers of outer membrane.The culture environment of Lawsonia intracellularis is very strict,it can't grow in any of the medium in use at present,including the chicken embryo,and it can only be cultured with special intestinal cell lines,such as mouse intestinal epithelial cell IEC-18,pig intestinal epithelial cell IPEC-J2 and mouse fibroblast McCoy,or with intestinal primary cells isolated from the host,and there are no CPE in the infected cells with this bacterium.What is more demanding is that the atmosphere should be kept at a low oxygen level of 8%,neither absolute oxygenfree nor normal oxygen are conducive to the growth of the bacteria.Lawsonia intracellularis is sensitive to antibiotics,preventive drug can inhibit the growth and reproduction of this bacterium and achieve the effect of preventing the disease.At present,antibiotics-free feeding mode has been increasingly emphasized abroad,and has been implemented in China too.Although there are vaccines on sale,they are rarely used.Under this background,the prevalence of the disease will definitely increase,which will seriously affect the development of pig industry,so it is necessary to investigate the prevalence of Porcine Proliferative Enteritis.In order to explore the prevalence of Procine Proliferative Enteritis in piggeries of Tai'an city and surrounding areas,to collect terminal ileum of pigs from a slaughterhouse in Tai'an,and fecal samples were collected from large-scale piggeries in Tai'an and surrounding areas by anal swab.The samples were comprehensively detected by pathological,histopathological and molecular biology technology,observe the lesions of the intestine by naked eyes,observe the pathological histology by HE staining and modified WS silverstaining respectively,observe the histopathological lesions by microscopy.The detection of pathogenic nucleic acid is carried out by conventional PCR,which is used to count the prevalence of Lawsonia intracellularis.The results are as follows: the prevalence of all the intestinal tissue is 57.97%(251/433),the positive rate of workshop batches is 100%;the prevalence of all the stool samples is 55.14%(192/321)and the positive rate of piggery is100%.Some ileum sample looks thick,and the thickening intestinal mucosa is like the gyrus after cutting the intestinal tube.Intestinal contents are all yellow stools with indigestion.The results of pathological histology shows that intestinal mucosal epithelial cells proliferated significantly,mucosal epithelial cells increased and glandular epithelial cells abnormal hyperplasia.In this study,the culture system of Lawsonia intracellularis was established according to reference articles,and IPEC-J2 cell lines were successfully infected with live Lawsonia intracellularis live vaccine strain,this system has low cost and simple operation,and is suitable for common laboratories,the bacterial culture condition was detected by IFA.This experiment has laid a foundation for further research in the future. |
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