The immunodominant and neutralization linear epitopes for SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) becomes a tremendous threat to global health. Although vaccines against the virus are under development, the antigen epitopes on the virus and their immunogenicity are poorly understood. Here, we simulated the three-dimensional structures of SARS-CoV-2 proteins with high performance computer, predicted the B cell epitopes on spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches, and then validated the epitope immunogenicity by immunizing mice. Almost all 33 predicted epitopes effectively induced antibody production, six of which were immunodominant epitopes in patients identified via the binding of epitopes with the sera from domestic and imported COVID-19 patients, and 23 were conserved within SARS-CoV-2, SARS-CoV and bat coronavirus RaTG13. We also found that the immunodominant epitopes of domestic SARS-CoV-2 were different from that of the imported, which may be caused by the mutations on S (G614D) and N proteins. Importantly, we validated that eight epitopes on S protein elicited neutralizing antibodies that blocked the cell entry of both D614 and G614 pseudo-virus of SARS-CoV-2, three and nine epitopes induced D614 or G614 neutralizing antibodies, respectively. Our present study shed light on the immunodominance, neutralization, and conserved epitopes on SARS-CoV-2 which are potently used for the diagnosis, virus classification and the vaccine design tackling inefficiency, virus mutation and different species of coronaviruses.

Analysis of guidance levels of radionuclide for food and drinking water / 中国医学装备

Objective:To investigate guidance levels of radionuclide for food and drinking water.Methods: According to the relevant standards and technical documents issued by international organizations, the computing methods of guidance levels of radionuclide for food and drinking water under the existing exposure situation and emergency exposure situation were analyzed and researched.Results: The calculated guidance levels of 17 radionuclides in drinking water and 20 radionuclides in food in existing exposure situation were provided, and the guidance levels of 24 radionuclides in food and drinking water in emergency exposure situation also were proposed. It was found that the relevant standards in China were lag and the standard of guidance levels of radionuclides activity concentrations for drinking water were deficient.Conclusion: It is suggested that the standards of guidance levels of radionuclide for food and drinking water in China should be formulated or revised by referring to international standard that issued from international organization and taking into account the specific conditions in China so as to preferably protect public health of our country.