ABSTRACT
Objective The aim of this study was to investigate the microbial contamination situation in infant formula powder during the processes of production.Methods A total of 880 samples were collected from Gansu Province,which included raw materials,manufacturing facilities,personnel swabs and final infant formula powder.The detection method conducted in this study were complied with the standard of the SN/T 0738-1997 and GB 4789,and the microbial species detected in this study included Enterobacteriaceae,Enterobacter sakazakii,and Bacillus cereus.Results The detection rate of Enterobacteriaceae was 28.41％ (250/880),the detection rates of Enterobacter sakazakii and Bacillus cereus were 0.46％ (4/872) and 16.94％ (31/183) respectively.The prevalence of Enterobacteriaceae (40.00％,40/100) was the highest in raw materials.Four Enterobacter sakazakii strains were isolated from the pretreatment workshop,equipment and environment surface.The prevalence of Bacillus cereus was 22.73％ (10/44) in final product.Conclusion The microbial contamination was existent widely in infant formula powder and the production procession.Rigid laws and managements should be conducted to reduce the microbial contamination in raw materials,production processes and the environment,which might improve the quality of infant formula powder.
ABSTRACT
<p><b>OBJECTIVE</b>To clone and express the recombinant capsid protein VP2 of enterovirus type 71 (EV71) and to identify the immune activity of expressed protein in order to build a basis for the investigation work of vaccine and diagnostic antigen.</p><p><b>METHODS</b>VP2 gene of EV71 was amplified by PCR, and then was cut by restriction enzyme and inserted into expression vector pMAL-c2X. The positive recombinants were transferred into E.coli TB1, the genetically engineered bacteria including pMAL-c2X-VP2 plasmids were induced by isopropyl thiogalactoside ( IPTG) , and the expression products were analyzed by SDS-PAGE and western blotting method. EV71 IgM antibody detection method by ELISA was set up, and the sensitivity and specificity of this method was assessed; 60 neutralizing antibody positive serum samples from hand foot and mouth disease (HFMD) patients were determined, of which 52 samples were positive and 8 samples were negative; a total of 88 acute phase serum samples of HFMD patients diagnosed in clinical were also detected.</p><p><b>RESULTS</b>VP2 gene of 762 bp was obtained by PCR, the gene segment inserted into the recombinant vector was identified using restriction enzyme digestion. The recombinant vector could express a specific about 71 500 fusion protein in E.coli by SDS-PAGE. The purified recombinant protein of EV71-VP2 can react with the serum of HFMD patients to produce a specific band by western blotting. The sensitivity and specificity of ELISA was 87% and 83%, respectively. Of the 88 acute phase serum samples from children with HFMD, 48 samples (55%) were positive by the ELISA assay.</p><p><b>CONCLUSIONS</b>VP2 gene of EV71 has been cloned and a prokaryotic high expression system for VP2 gene was successfully constructed in the present study. The recombination EV71-VP2 has well antigenicity, which could be useful for developing diagnose reagent or vaccine of EV71.</p>
Subject(s)
Humans , Antibodies, Neutralizing , Blood , Antibodies, Viral , Blood , Capsid Proteins , Genetics , Allergy and Immunology , Enterovirus A, Human , Genetics , Allergy and Immunology , Enzyme-Linked Immunosorbent Assay , Genetic Vectors , Hand, Foot and Mouth Disease , Allergy and Immunology , Immunoglobulin M , Blood , Recombinant Proteins , Genetics , Allergy and ImmunologyABSTRACT
To investigate the animals infection situation of novel bunyavirus in Xinyang City ,Henan Province ,China , animal serum samples such as cattle ,dog ,swine ,mice were collected in Shangcheng County and Guangshan County in Xinyang City .All the serum samples were detected by novel bunyavirus ELISA and real time RT-PCR method .A total of 292 animal serum samples were collected including 5 kinds of animals .The result of all the animal serum samples were negative by using real time RT-PCR ,and the positive rate was 45 .19% (141/312) by ELISA method .Of the 5 animal serum samples including mice ,cattle ,goats ,swine and dogs ,the positive rate were detected to be 1 .06% ,100 .00% ,76 .27% ,3 .57% ,and 75 .00%respectively .There was significant difference in results among 5 kind of animal serum antibodies .Animals such as cattle and dog may be the host of novel bunyavirus which were detected novel bunyavirus antibodies in cattle and dog in Xinyang City , Henan Province ,China .