Objective:To evaluate the immunogenicity of an experimental SARS-CoV inactivated vaccine.Methods:The virus suspension of F69 strain was inactivated with 0.4% formaldehyde and purified,then used as the immune antigen combined with Freund′s adjuvant.Eight adult New Zealand rabbits were immunized 4 times with this vaccine.12 sets of rabbit serum were sampled from the third day to 74th day after first immunization.Titers of specific IgG antibody and neutralizing antibody were determined by indirect ELISA and micro-cytopathic effect neutralizing test.Results:Rapid and potent humoral immune responses were induced by F69 inactivated vaccine in all eight immunized rabbits.Both specific IgG antibody and neutralizing antibody all peaked just with 2 vaccinations,with the maximum titer of 1∶81 920 and 1∶20 480 respectively about 6 weeks after first immunization.Across neutralizing reaction existed between F69 and Z2-Y3 strains.Conclusion:F69 inactivated vaccine owns strong immunogenicity.Similar antigenic epitopes exist between the F69 strain and Z2-Y3 strain,which ensured the cross neutralizing reaction.

Background::Clinical opportunistic screening is a cost-effective cancer screening modality. This study aimed to establish an easy-to-use diagnostic model serving as a risk stratification tool for identification of individuals with malignant gastric lesions for opportunistic screening.Methods::We developed a questionnaire-based diagnostic model using a joint dataset including two clinical cohorts from northern and southern China. The cohorts consisted of 17,360 outpatients who had undergone upper gastrointestinal endoscopic examination in endoscopic clinics. The final model was derived based on unconditional logistic regression, and predictors were selected according to the Akaike information criterion. External validation was carried out with 32,614 participants from a community-based randomized controlled trial.Results::This questionnaire-based diagnostic model for malignant gastric lesions had eight predictors, including advanced age, male gender, family history of gastric cancer, low body mass index, unexplained weight loss, consumption of leftover food, consumption of preserved food, and epigastric pain. This model showed high discriminative power in the development set with an area under the receiver operating characteristic curve (AUC) of 0.791 (95% confidence interval [CI]: 0.750–0.831). External validation of the model in the general population generated an AUC of 0.696 (95% CI: 0.570–0.822). This model showed an ideal ability for enriching prevalent malignant gastric lesions when applied to various scenarios.Conclusion::This easy-to-use questionnaire-based model for diagnosis of prevalent malignant gastric lesions may serve as an effective prescreening tool in clinical opportunistic screening for gastric cancer.