Objective: To investigate the nutritional status and its influencing factors among primary and middle school students in Yunfu City, Guangdong Province, so as to provide the basis for improving nutrition and health strategies for students. Methods: Primary and middle school students from 26 schools in 5 counties (cities, districts) of Yunfu City were selected in 2022 through multi-stage stratified cluster random sampling method. Demographic information, dietary and exercise behaviors were collected using questionnaire surveys, and the prevalence of malnutrition were analyzed. Factors affecting malnutrition was evaluated using a multinomial logistic regression model. Results: A total of 7 213 students were surveyed, including 3 881 boys (53.81%) and 3 332 girls (46.19%), and had a median age of 13.50 (interquartile range, 4.00) years. There were 2 667 primary school students (36.97%), 2 662 middle school students (36.91%) and 1 884 high school students (26.12%). There were 1 938 students suffered from malnutrition, with a detection rate of 26.87%. The detection rates for undernutrition, overweight and obesity were 11.66%, 9.75% and 5.46%, respectively. Multinomial logistic regression analysis showed that gender (boy, OR=2.227, 95%CI: 1.905-2.603), studying phase (primary school, OR=1.528, 95%CI: 1.239-1.884), ≥60 min/d of moderate/high-intensity exercise (0-1 d/week, OR=1.422, 95%CI: 1.153-1.753; 2-4 d/week, OR=1.280, 95%CI: 1.047-1.564) and frequency of having physical education (1-2 classes/week, OR=1.732, 95%CI: 1.084-2.767; 3-4 classes/week, OR=1.662, 95%CI: 1.026-2.693) were the influencing factors for undernutrition; gender (boy, OR=1.956, 95%CI: 1.656-2.311), frequency of sugary beverage intake (0 time/d, OR=0.721, 95%CI: 0.528-0.984) and frequency of having physical education (0 class/week, OR=2.087, 95%CI: 1.151-3.784; 1-2 classes/week, OR=1.644, 95%CI: 1.044-2.590; 3-4 classes/week, OR=1.685, 95%CI: 1.051-2.703) were the influencing factors for overweight; gender (boy, OR=2.459, 95%CI: 1.964-3.078) was the influencing factor for obesity among students. Conclusions Undernutrition, overweight and obesity coexist in primary and middle school students in Yunfu City. Gender, school phase, frequency of sugary beverage intake and frequency of having physical education are associated with malnutrition among primary and middle school students.

ObjectiveThe human angiotensin converting enzyme2 （hACE2） transgenic mouse model was used to clarify the antiviral efficacy of BD-77 against a novel coronavirus SARS-CoV-2 and explore the action mechanism of BD-77 against SARS-CoV-2. MethodSARS-CoV-2 Omicron and Delta variant strains-infected VeroE6 cell models were established and administered with BD-77 to observe the antiviral effect of BD-77 in vitro. A kit was used to detect the effect of BD-77 in vitro on the binding of spike S protein of SARS-CoV-2 virus （Delta/Omicron） to angiotensin converting enzyme2 （ACE2）. Chromatography was adopted to detect the binding of BD-77 to the S protein and N protein of the novel coronavirus. hACE2 transgenic C57BL/6 mice were divided into a blank control group， SARS-CoV-2 infection group， BD-77 administration groups of 37.5 mg·kg^-1 and 75 mg·kg^-1， with eight mice in each group. The pneumonia model of SARS-CoV-2-infected hACE2 transgenic mice was built to observe the survival of the mice， detect the virus titer of the lung tissue of the mice， and observe the lesions in the lung tissue. ResultBD-77 had a certain inhibitory effect on Omicron and Delta variant strains in vitro， with median inhibitory concentration （IC₅₀） of 526.3 mg·L^-1 and 653.0 mg·L^-1， respectively. BD-77 had no significant inhibitory effect on the binding of the S protein of WT， Omicron， and Delta variant strains of SARS-CoV-2 to ACE2 and had no binding effect with the S protein and N protein of the novel coronavirus. No mice in the blank group died， while the mortality rate of SARS-CoV-2-infected mice was 75%. There was a large amount of virus replication in the lung tissue of the mice and large areas of inflammatory infiltration in the lung tissue and interstitium. Compared with the model group， BD-77 administration groups of 37.5 mg·kg^-1 and 75 mg·kg^-1 could reduce the mortality of mice， significantly lower the virus titer in the lung tissue of mice （P<0.05）， and improve lung lesions. ConclusionBD-77 demonstrated significant inhibitory effects against SARS-CoV-2 virus in vitro and in vivo. However， its mechanism of action did not involve direct inhibition of the virus itself or intervention in the virus-host binding process. This finding suggests that the mechanism of action of BD-77 needs to be thoroughly investigated and elucidated by further experiments.