Low toxicity and high immunogenicity of an inactivated vaccine candidate against COVID-19 in different animal models.

The ongoing COVID-19 pandemic is causing huge impact on health, life, and global economy, which is characterized by rapid spreading of SARS-CoV-2, high number of confirmed cases and a fatality/case rate worldwide reported by WHO. The most effective intervention measure will be to develop safe and effective vaccines to protect the population from the disease and limit the spread of the virus. An inactivated, whole virus vaccine candidate of SARS-CoV-2 has been developed by Wuhan Institute of Biological Products and Wuhan Institute of Virology. The low toxicity, immunogenicity, and immune persistence were investigated in preclinical studies using seven different species of animals. The results showed that the vaccine candidate was well tolerated and stimulated high levels of specific IgG and neutralizing antibodies. Low or no toxicity in three species of animals was also demonstrated in preclinical study of the vaccine candidate. Biochemical analysis of structural proteins and purity analysis were performed. The inactivated, whole virion vaccine was characterized with safe double-inactivation, no use of DNases and high purity. Dosages, boosting times, adjuvants, and immunization schedules were shown to be important for stimulating a strong humoral immune response in animals tested. Preliminary observation in ongoing phase I and II clinical trials of the vaccine candidate in Wuzhi County, Henan Province, showed that the vaccine is well tolerant. The results were characterized by very low proportion and low degree of side effects, high levels of neutralizing antibodies, and seroconversion. These results consistent with the results obtained from preclinical data on the safety.

[Study on preventing effects of procyanidins on selenite cataract development in rats].

OBJECTIVE: To study the preventing effects of procyanidins (PC) on selenite cataract in rats and the time-effect relationship. METHOD: Forty five SD rats were divided into three groups: control, model and experiment groups. The rats in the experiment group were fed additionally with the PC by 80 mg x kg(-1) when they were supplied the equal selenite with the model group. Five rats of each group were regularly sacrificed by bleeding from femoral artery at sixth, eleventh, sixteenth day and the level of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) of all lenses was measured. RESULT: Compared with the model group, the level of the MDA in the experiment group at the eleventh day and the sixteenth day greatly decreased (P < 0.01). At the sixteenth day the level of the SOD and GSH-Px had an increase (P < 0.01), which showed its anti-oxygenation. CONCLUSION: PC indicated the obvious inhibition in the development of the rat cataract. The treatment period was recommended at least for fifteen days.

[The expression rule of proliferating cell nuclear antigen in rat thyroid of hyperplasia induced by propylthiouracil].

OBJECTIVE: To study the expression rule of proliferating cell nuclear antigen (PCNA) in thyroid when the hyperplasia of male rat thyroid is induced by propylthiouracil (PTU). METHODS: PTU was administered to rats by gavage at a dose of 5.0 mg/kg B. W for 0,3,6,9 and 12 days respectively. All animals were sacrificed after the last dosage, and the expression of PCNA in thyroid was detected by immunohistochemistry and RT-PCR. RESULTS: Compared with the control group, the PCNA level in the thyroid of rats given PTU for 3 days significantly increased (P < 0.05),and reached the highest expression when it was 6 days, but then when it was 9 days and 12 days, the PCNA expression showed a descending tendency. CONCLUSION: PCNA has a expression rule in hyperplastic thyroid: expression increase first but then decrease. This rule confirms the histological change of thyroid in earlier stage. The experimental time of assessment test to thyroid hormone disruptors will be shortened to six days.