ABSTRACT
Objective Vaccination is a most effective method for the prevention of severe diseases caused by pandemic influenza and microRNA ( miRNA) mediated gene silencing has offered a novel approach to the construction of new vaccines.Our study aimed to construct a recombinant influenza A ( H1 N1 ) virus with the PB1 gene that carries the target fragment of miRNA Let-7b. Methods After comparing the sequence of the A/Nanjing/108/2009 H1N1 viral fragments with that of Let-7b, we selected PB1 as the optimal gene sequence, inserted the Let-7b binding target gene into PB1, ligated the modified fragments with pDP 2000, and named the recombinant plasmids pDP-mu-PB1 and pDP-sclb-PB1, respectively.We co-transfected the MDCK and 293T cells with the recombinant and other seven plasmids and injected the supernatant into the allantoic cavity of the chickenembryo for virus propagation, followed by detection of the virus by hemagglutination ( HA) assay and measurement of the viral titer by TCID50 .We amplified the viral cRNA by RT-PCR and identified the viruses by agarose gel electrophoresis and nucleotide sequence analysis. Results PB1 was the optimal sequence ( 83 bp -107bp) for the attenuation of viruses.The HA-titers of miRT-H1N1 and scbl-H1N1 were 1∶32 and 1∶64, and their viral loads were 4.68 ×105 and 7.94 ×104 TCID50/mL, respectively.Nucleotide sequence analysis showed the expected fragment in the rescued virus. Conclusion A recombinant strain vaccine was successfully constructed, which has laid the foundation for fur-ther assessment of virulence.
ABSTRACT
Objective To investigate the occurrence of central venous catheter-related bloodstream infection(CRB-SI)in mass severe burn patients,evaluate related risk factors for infection,and effectiveness of prevention and con-trol measures.Methods In August 2014,9 cases of severe burn patients were rescued in a hospital,all patients re-ceived CVC,infection prevention and control intervention measures were performed during the whole process of catheterization.Results All patients received 30 episodes of CVC,total CVC-days were 227 days,bacterial culture for three-cavity catheters of femoral veins in 2 patients were positive,incidence of CRBSI was 8.81 ‰;1 patient was isolated Enterococcus faecium ,1 isolated both Acinetobacter baumannii and Stenotrophomonas maltophilia .2 CRB-SI patients received femoral vein catheterization,catheterization site was trauma surface,duration of catheterization were both ≥7 days,both used three-cavity catheters,and third degree burns were ≥60%,both patients were cured after timely removal of catheters and receiving of antimicrobial agents.Conclusion CVC is helpful for long term, safe and effective fluid infusion,but it can cause CRBSI;infection prevention and control intervention for patients receiving CVC during the whole process of catheterization can reduce the occurrence of CRBSI.
ABSTRACT
Objective To explore the change trend and antimicrobial resistance of pathogens causing infection in extensive burn patients,and provide reference for clinical prevention and treatment.Methods Specimens from 9 extensive burn patients who were admitted to a hospital at the same time were performed pathogenic culture and an-timicrobial susceptibility testing, change trend and antimicrobial susceptibility of pathogens were observed. Results The main specimen was wound secretion,accounting for 93.81 %.The major pathogens causing infection were Acinetobacter baumannii (44.85%),Staphylococcus aureus (32.47%),Pseudomonas aeruginosa (12.37%), and Klebsiella pneumoniae (5.15%).With the prolongation of hospital stay,pathogens changed from one kind to multiple strains, and from susceptibility to resistance,multidrug resistance,and extensive drug resistance. Conclusion Itis difficult to avoid infection in burn patients,timely realizing the changes of pathogens causing infec-tion and antimicrobial resistance play an important role in the control of infection.