动物造模,药效评价 z-bio 2024-07-02 397

　　Toxoplasma gondii is a common parasitic protozoa that seriously affects human health worldwide. The ultimate host is cats, and the intermediate host is over 200 mammals (including humans) and birds. Toxoplasmosis can be classified into three types: congenital, acquired, and ocular (which can be congenital or acquired), most of which manifest as latent infections. The harm of congenital toxoplasmosis (caused by transmission through the placenta) is particularly severe. In China, Liu Tao et al. conducted research on the infectivity of rats, mice, and long clawed gerbils using RH virulent strains through different pathways and infection levels, and concluded that mice and long clawed gerbils are highly susceptible and have a short survival time after infection. They can only be used as good animals for conservation and obtaining a large amount of antigens. Juvenile rats are also susceptible to Toxoplasma gondii, but their resistance is significantly stronger than that of mice and long clawed gerbils. However, their survival time is not long, and they cannot be used as a model of latent infection in animals. Adult rats can survive for more than 3 months after infection and gradually enter a latent infection state after 70 days. Therefore, rats can be used as animal models for latent infection of Toxoplasma gondii; Zhang Jie et al. used human international standard strain (RH strain) of Toxoplasma gondii tachyzoites with different doses of cryoresuscitation to inoculate mice at different pregnancy stages. After treatment with a certain dose of diethylstilbestrol (DES), their miscarriage and fetal brain tissue infection were observed, and a mouse model of vertical transmission of Toxoplasma gondii was established. In foreign countries, Roberts et al. studied mouse models of congenital Toxoplasma gondii infection and concluded that the immunity of animals infected with Toxoplasma gondii depends on the type of animal. Toxoplasmosis in Swiss mice can continue to spread between generations, while congenital Toxoplasmosis in BALB/c mice and BALB/K mice only occurs during the first infection during maternal pregnancy. Infection before pregnancy can provide immunity to the fetus, and the vertical transmission of these two types of mice is similar to that of humans.

　　1. Animal model of latent infection of Toxoplasma gondii

　　(1) The replication method involves inoculating 1 × 100000 tachyzoites of Toxoplasma gondii RH virulent strain into the abdominal cavity of rats, aged 11-12 weeks, and weighing 200-220g.

　　(2) Model characteristics: Infected animals can generally survive for more than 3 months. IgM antibodies gradually increase from the 10th day, reach their peak on the 70th day, and gradually decrease thereafter, while IgG gradually increases from the 50th day, gradually replacing macromolecular IgM. Within 70 days, there is still activity of Toxoplasma gondii, and after 70 days, it gradually enters a latent infection state. (3) Compared to medical infected animals, due to their strong immunity, Toxoplasma gondii forms cysts in the body and enters a latent infection state after 70 days. This is similar to most human infections that are latent infections, asymptomatic with worms, lurking in the brain tissue, muscles, retina, and other organs in the form of cysts for a long or even lifetime. This model animal can be used for research on the damage of Toxoplasma gondii to various systems, drug screening, and diagnosis of Toxoplasmosis.

　　2. Animal model of vertical transmission of Toxoplasma gondii

　　(1) Method of replication: ① Inoculate 1 × 100000 tachyzoites of Toxoplasma gondii into the abdominal cavity of mice. After 72 hours, aseptic extraction of mouse abdominal fluid was performed, followed by centrifugation, washing, filtration purification, counting, and preparation with PBS to form 1 × 100000000/L liquid nitrogen for cryopreservation. After recovery, the mice were used for inoculation. ② Select BALB/c mice aged 8-10 weeks. ③ Prepare DES. ④ Virgo mice mate with male mice in the same cage, observe the vaginal plug, and the day of discovery of the vaginal plug is considered the 0th day of pregnancy. On the 8th day of pregnancy, 400 tachyzoites of Toxoplasma gondii were inoculated and resuscitated. ⑤ On the 10th and 13th day of pregnancy, DES 1mg/100g was subcutaneously injected.

　　(2) The BALB/c mouse model of vertical transmission of Toxoplasma gondii established using this method can achieve a low abortion rate without all vertical transmission occurring. The occurrence of vertical transmission is similar to that of humans.

　　(3) Compared to traditional medicine, the inoculation of Toxoplasma gondii tachyzoites into mice can easily cause death. The use of cryopreserved tachyzoites to inoculate pregnant mice can reduce their mortality. The earlier the vaccination time and the higher the vaccination dose, the more pregnant mice will experience complete miscarriage. Infected with tachyzoites or oral capsules at different gestational times can affect fetal absorption and miscarriage in mice. The effects of pregnancy hormones, especially estrogen, affect cellular immunity, thereby affecting the outcome of Toxoplasma gondii infection during pregnancy. Different animals have different immune responses to Toxoplasma gondii infection. This model animal can be used for research on the prevention and treatment of congenital toxoplasmosis.