| Shigella is a genus of gram-negative bacilli. It has been proved to be the pathogen of causing human disease. Shigella can be divided into four groups:Shigella flexneri, Shigella boydii. Shigella sonnei and Shigella dysentery. S. Shigella are often found in developing countries, and cause more mortality than any other Shigella group. By invading the colonic mucosa. S. Shigella can cause human’s bacillary dysentery, accompanying with a strong inflammatory response in human intestine after enter into intestinal epithelial cells, at the same time, leading to the destruction of colonic mucosa. In2004. LanJu Xu, ChuanQing Wang discovered that Shigella can infected the chickens, this discovery has great significance to public health. The study on Shigella invasion mechanism to mammals has being carried out in many countries, and the study reports have been recognized by the researchers, but the study on chicken infected with Shigella hasn’t been done. Therefore, we made a preliminary study on the pathogenicity of Shigella on SPF chicken. dynamic invasion process to intestine and related reportors, in order to provide a research base for the invasion mechanism of Shigella on chicken.To assess the pathogenicity of Shigella on SPF chicken in a lab environment, we select the3-day old SPF chickens as infection targets, the SPF chickens were challenged with S. Shigella by craw injection and intraperitoneal injection, isolated from human. The clinical symptoms, necropsy lesions and mortality were monitored, and then histopathological observation was carried out. The results show human S. Shigella can cause SPF chickens disease and death. Disease severity varied in different infection routes. Chickens with intraperitoneal injection were more severe than chickens with craw injection. Pathological change of intestinal tissue is obvious, but heart, liver and other tissues is not. In conclusion, human S. Shigella is pathogenic on SPF chickens and can cause severe lesions on chickens intestinal tissue, it has a certain influence on heart and liver.To further study the invasion characteristics and approximate invasion site after human S. Shigella entry into chickens’ intestine, intestinal loops infection test was performed on3-day old SPF chickens. After inoculatin, the intestinal tissues were respectively took out at2h,6h,12h, and then immunohistochemical observation and electron microscope observation were carried out. Immunohistochemical observation shows:Shigella can be observed in epithelial cells of jejunum and ileum, but can’t be observed in epithelial cells of duodenum, cecum and rectum. electron microscope observation shows:Shigella also exist in the jejunal and ileum epithelial cells. The test results suggested that human S. Shigella mainly invade the epithelial cells of jeiunum and ileum.To understand the expression temporal and spatial expression characteristics of β1in chicken intestine, a pair of primers was designed for proving the presence of (31in chicken intestine. Another pair of primers for Real-time PCR was designed to establish a rapid and specific SYBR Green I Real-time PCR assay,β1expression levels of1-20day-old chickens intestinal tissue were detected by using the assay. Meanwhile, the specificity, sensitivity and repeatability of the assay were tested. The results show that β1mRNA was successfully identified in chicken intestine; The established SYBR Green I Real-time PCR for detecting the expression level of β1in chickens is rapid, specific and sensitive, and can be used as a useful tool. The expression levels of β1differed in different day-old chicken intestinal tissue, the expression levels of β1were higher in5to10day-old chicken jejunum, ileum and rectum than duodenum and cecum. The duodenum and cecum β1mRNA expression levels decreases as chickens’age increases, and Jejunum, ileum and rectum show the upward trend.In conclusion, This study preliminarily proved that human S. Shigella is pathogenic to chickens, β1is exists in chicken’s intestinal tissue, the expression level of β1may be relaed to the age of infected chickens. This paper may provide a basis for further study on the invasion mechanism of Shigella-infected chickens. |
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