动物造模,大肠杆菌小鼠感染模型 z-bio 2023-10-12 1194

　　Usually, mice are not sensitive to infection with wild-type EHEC O157: H7, and adult mice of IQI, BALB/c, KM, and other strains are not susceptible to O157. Inoculation with live EHEC O157 EDL933W (NalR) at a dose of 10 to the 10th does not cause significant infection symptoms in weaned mice. Therefore, in addition to using bacterial infections, medication should also be used to enhance the sensitivity of animals in order to replicate some of the symptoms of human EHEC infection, which can be used for preliminary screening of anti-O157: H7 vaccines.

　　(1) Method: Oral inoculation of bacteria (this strain is resistant to naphthylpyruvate), fasting for 12 hours before gavage. Restore diet 12 hours after inoculation. Inoculate with intraperitoneal injection of mitomycin (2.5mg/kg) and add naphthoquinoic acid (50%) to drinking water μ G/ml).

　　(2) Infection dose: 10 to the 9th power to 4 × 10 to the 9th power of live bacteria/piece.

　　(3) Result: The infected mice developed disease and died within 3-4 days. This model can replicate the classic histopathological changes of O157: H7 infection, including hemorrhage and edema in the lamina propria. Colon biopsy specimens show neutrophil infiltration, but the lesions are not severe, there is no A/E damage, and there is no cause of diarrhea or colitis. It should not be a direct cause of mouse death. In the experiment, EDL933W can cause damage to mouse renal parenchymal cells; The liver cells exhibit severe granular and vesicular degeneration, with more severe degeneration of the liver cells around the central vein of the liver lobule; The pathological changes in lung tissue are most obvious, with highly flexible and dilated capillaries in the alveolar wall, containing a large amount of red blood cells. The alveolar cavity contains pink serous fluid and a small amount of red blood cells, and local lung tissue bleeding. Some alveoli show compensatory emphysema changes, and typical E. coli granulomas can be seen around the bronchi, with a large number of epithelioid cells and inflammatory cell infiltration. The possible reason is that there are more Stx receptors Gb3 present in the lungs of mice.

　　Inject mitomycin (2.5mg/kg) intraperitoneally while inoculating bacteria, and add naphthoquinone acid to drinking water. The action of mitomycin is similar to that of cyclophosphamide, which can cause a decrease in white blood cells and platelets. EHEC O157 is a lysogenic bacterium, and mitomycin can increase the release of Stx2 phage, thereby increasing the production of EHEC characteristic virulence factor Shiga toxin Stx. The effect of naphthoquinonic acid is to inhibit the normal microbiota in the intestine, making EHEC O157 EDL933 W (NalR) a dominant microbiota in the intestine. If EHEC is infected orally or in the stomach, it is usually necessary to use streptomycin in advance to clear the normal bacterial community in the animal's intestine, thereby allowing the colonization of streptomycin resistant strains of EHEC in the intestine. The kidneys of mice infected with EHEC in this way showed renal tubular necrosis damage. In addition, mouse models have also been used to study the oral and non oral EHEC infections of Stx. Intraperitoneal injection of Stx1 or Stx2 can cause colonic mucosal necrosis and bleeding, lymphatic necrosis in various tissues, and nephrotoxic tubular necrosis.