动物造模,SARS感染 z-bo 2022-02-04 391

　　(1) Reproduction method Healthy rhesus macaques (Rhesus macaques) and cynomolgus monkeys (M. fascicularis) aged 3 to 6 years old are newly anesthetized by intramuscular injection of fast sleep at a dose of 0.15ml/kg body weight, and then intranasally and Intratracheal infection of SARS-CoV BJ01 strain (10 to the power of 5.7 TCID50/ml). Virus was isolated from throat swabs of model animals on the second, fifth, and seventh day after challenge, and the virus was identified as SARS virus by immunofluorescence. Some infected monkeys have bleeding spots or spots in their lungs. All infected monkeys can develop multifocal mononuclear interstitial pneumonia of varying severity, manifested by widened alveolar septum, bleeding, and exudation. There are exfoliated alveolar epithelial cells and macrophages in the alveolar cavity, and small bronchi And bronchioles also have epithelial cells shedding; a small amount of inflammatory cell infiltration dominated by lymphocytes appears in some alveolar compartments, and hyaline membrane formation is occasionally seen in the alveolar cavity. Immunohistochemistry can detect SARS virus antigens in alveolar macrophages and type I epithelial cells. In the autopsy of infected animals, viral RNA can be detected in the bronchial lymph nodes and myocardium, and there are inflammatory changes. Most model animals developed hepatitis dominated by multifocal lymphocytic infection, accompanied by individual hepatocyte necrosis.

　　(2) Model characteristics After infection, model animals have pathological changes. The lungs are the main target organs of virus infection. Diffuse alveolar damage can be seen in each lung lobe, which forms hyaline membranes, and mononuclear cell infiltration appears. The SARS virus RNA can be detected from tissue samples such as blood, throat swabs, alveolar epithelial cells and bronchial lymph nodes of model animals through virological testing and immunological methods, indicating that the virus can replicate in non-primate animals; Cellular immune response. The number of white blood cells and platelets in some infected monkeys decreased temporarily from the third day of infection, and then gradually returned to normal levels; the animals produced specific antibodies to the SARS virus in the second, third, and fourth weeks after infection. The level of specific antibodies against SARS-CoV in serum is relatively high. It can be seen that the rhesus monkey can be used as an animal model of SARS virus infection, and is suitable for the study of SARS pathogenesis, drug screening, and vaccine evaluation.

　　(3) Comparative medicine All infected monkeys have not observed typical clinical symptoms of SARS such as high fever, dry cough, lethargy, transient rash, and difficulty breathing. 2/3 of rhesus monkeys have transient low fever; The body temperature of cynomolgus monkeys fluctuates within a normal range. However, the pathological changes in the lung tissue of infected monkeys, such as diffuse alveolar injury, monocyte infiltration, etc., are basically similar to those of human lung tissue after SARS coronavirus infection, and the pathological changes are milder than humans. SARS-specific antibodies can be produced in model animals after infection. The antibody level in their serum is higher at about 4 weeks after infection, which is the same as that of human SARS patients; the specific IgM antibodies produced in SARS patients appear from the 7th day to the first The peak can be reached on the 11th; while the IgG antibody is produced after 10d and reaches the peak at 20d; at the same time, the virus is isolated from the tissues and secretions of the infected monkey. In short, the pathological changes of rhesus monkeys infected with SARS virus are very similar to those of humans infected with SARS virus, and non-human primates have a genetic background similar to humans, so they can become ideal SARS animal models. However, limited by objective conditions, monkeys cannot be used in large-scale research. This restriction reduces the application value of this model.