ABSTRACT
<p><b>OBJECTIVE</b>To develop a system to rescue virus by intracellular expression of T7 RNA Polymerase.</p><p><b>METHODS</b>The gene of T7 RNA Polymerase was amplified and cloned to VR1012 by molecular biological technology. The expression plasmid VR-1a was then identified. VR-1a and EV71 infectious plasmid were co-transfected in Vero cell. CPE was observed and viral gene viral antigen were detected.</p><p><b>RESULTS</b>The gene of T7 RNA Polymerase was successfully cloned into vector VR1012. Vero cell developed to CPE after being transfected VR-1a and EV71 infectious plasmid. EV71 gene was amplified by RT-PCR from the culture. EV71 antigen was also detected by ELISA.</p><p><b>CONCLUSION</b>The method can be used to rescue virus. It could apply to immunologic research of EV71 DNA vaccine.</p>
Subject(s)
Animals , Humans , Chlorocebus aethiops , DNA-Directed RNA Polymerases , Genetics , Metabolism , Enterovirus A, Human , Genetics , Physiology , Gene Expression , Genetic Engineering , Methods , Genetic Vectors , Genetics , Metabolism , HeLa Cells , Plasmids , Genetics , Metabolism , Transfection , Vero Cells , Viral Proteins , Genetics , Metabolism , Virus ReplicationABSTRACT
<p><b>OBJECTIVE</b>To study main risk factors that cause foodborne diseases in food catering business.</p><p><b>METHODS</b>Data from references and investigations conducted in food catering units were used to establish models which based on @Risk 4.5 with Monte Carlo method referring to food handling practice model (FHPM) to make risk assessment on factors of food contamination in food catering units. The Beta-Poisson models on dose-response relationship to Salmonella (developed by WHO/FAO and United States Department of Agriculture) and Vibrio parahaemolyticus (developed by US FDA) were used in this article to analyze the dose-response relationship of pathogens.</p><p><b>RESULTS</b>The average probability of food poisoning by consuming Salmonella contaminated cooked meat under refrigeration was 1.96 × 10(-4) which was 1/2800 of the food under non-refrigeration (the average probability of food poisoning was 0.35 at room temperature 25°C). The average probability by consuming 6 hours stored meat under room temperature was 0.11 which was 16 times of 2 hours storage (6.79 × 10(-3)). The average probability by consuming contaminated meat without fully cooking was 1.71 × 10(-4) which was 100 times of consuming fully cooked meat (1.88 × 10(-6)). The probability growth of food poisoning by consuming Vibrio parahaemolyticus contaminated fresh seafood was proportional with contamination level and prevalence.</p><p><b>CONCLUSION</b>The primary contamination level, storage temperature and time, cooking process and cross contamination are important factors of catering food safety.</p>