The Doha Declaration has entrusted to the members of WHO the right to use the compulsory licensing for drug patents in the face of global public health crises.Although the basic compulsory licensing system for drug patents has been established in China, the efficiency of its implementation is low, the responsibility of its executive departments is unclear, the related rules are not fully understood by pharmaceutical enterprises, it is thus necessary to improve and perfect the relevant legal provisions and systems in order to effectively improve the accessibility of drugs.

Objective: To investigate knowledge, attitude and purchase behavior for snack nutrition among parents of school aged children in Shenzhen, so as to provide support and scientific basis for developing targeted intervention program for child healthy dietary behavior. Methods: Through cluster random sampling method, a total of 4 517 parents of students graded in 2 from 116 primary schools in Shenzhen were invited to participate into a self administered questionnaire survey. Results: Parental cognition towards snack nutrition varied substantially. The majority of parents were worried about the health and safety issues of snack and were aware of the risk of eating disorder of consistent snakc consumption in children. Only 21.18% of parents reported frequent snack purchasing behaviors. Children s snacks, mainly included milk, dairy products, vegetable, fruit, bread and cake, are mostly purchased by parents, and the snack choices were related to nutrition, hygiene and taste. In addition, most parents paid attention to the production date whereas less than one third of them read the nutrition facts labels. Parents with different knowledge level towards snack nutrition differed in eating attitude and behavior. Conclusion Parents should be further educated about nutrition and food safety knowledge to improve nutritional literacy, as well as attitude towards healthy diet and snack purchasing ehavior to better guide their children to develop good eating habits.

Objective:To prepare camel-derived nanoantibodies that can bind to the recombinant protein VirB12 antigen with high affinity and lay the foundation for further research.Methods:Xinjiang Bactrian camels were immunized six times with VirB12 recombinant protein, total RNA was extracted from lymphocytes isolated from peripheral blood, and the VHH gene fragment was amplified by nested PCR to construct a phage VHH display library. ELISA solid-phase affinity and enrichment methods were used for screening. After three rounds of affinity screening, the clones enriched in the second and third rounds were randomly picked out, and the binding of a nanoantibody with soluble expression to VirB12 was analyzed by ELISA. After sequence determination and multiple alignment, repetitive sequences were removed, and finally five non-redundant sequences were obtained, which were named D1, E6, H8, H9, and H10. The five identified nanoantibody genes were transformed into the WK6 strain, and the soluble expression of an intercellular substance was carried out at 16 °C. After purified expression of Ni-NTA, the binding ability and thermal stability of nanoantibodies and the antigen VirB12 protein were detected by Western Blot and ELISA.Results:Five strains of nanoantibodies were expressed in WK6 bacteria in soluble form. SDS-PAGE showed that the purity of five anti-VirB12 nanoantibodies was close to 90%, and they had high antigen-binding activity and obvious antigen-antibody concentration dependence. All four strains of nanoantibodies showed high thermal stability, and after being treated at 90 ℃, they could still retain more than 60% binding activity.Conclusions:In the study, a VHH phage display library with a capacity of 2.8×10 8 cfu/ml was constructed from Xinjiang Bactrian camel lymphocytes immunized with VirB12 recombinant protein. Five anti-VirB12 nanoantibodies with high affinity and thermal stability were obtained through solid-phase screening and enrichment and soluble monoclonal ELISA detection. These results laid the foundation for further development of VirB12 nanoantibodies.