2. Loop-mediated isothermal amplification in detection of West Nile virus genome
Academic Journal of Second Military Medical University 2010;31(6):590-594
Objective: To establish a loop-mediated isothermal amplification (LAMP) assay for rapid detection of the West Nile virus (WNV). Methods: WNV genome (position nt 1 021 to nt 1 240) was synthesized by a PCR-based gene synthesis method. The synthetic fragments included 6 pairs of LAMP primer recognizing 8 primer sites of WNV genome. The LAMP gene amplification was carried out using a real-time PCR system at 63°C for 60 min, then the amplification was terminated at 80°C after 2 min. The amplification products were observed by agarose gel electrophoresis. The sensitivity and specificity of LAMP assay were compared with those of conventional PCR. Results: The LAMP assay took less than 20 min, and the amplification product took on a ladder-like electrophoresis pattern. The sensitivity of LAMP assay was 10-fold higher than that of conventional PCR, and the detection limit of LAMP was 9.23 copies/μl. The specificity of WNV-specific LAMP assay was demonstrated by the negative amplification results from dengue virus and Japanese encephalitis virus, both were closely related members of the Flavivirus family. Conclusion: LAMP assay is rapid, cost-effective, highly sensitive and specific in detecting genes of interest, and is of great significance for WNV surveillance, especially for grass root units and on-sport surveillance.
3. Rapid detection and typing of Dengue virus by single-tube nested multiplex-PCR
Academic Journal of Second Military Medical University 2010;31(2):152-156
Objective: To establish a single-tube nested multiplex-PCR assay for rapid detection and typing of Dengue viruses for multiple infections with different serotypes. Methods: A pair of outer universal primers designed for all the four Dengue virus serotypes were used to amplify the mixed RNA of 1-4 dengue viral serotypes by one-step RT-PCR, and the products were used as template for nested multiplex PCR using four pairs of serotype-specific primers in the same reaction tube. The sensitivity and specificity of single-tube nested multiplex PCR assay amplifying from the mixed 1-4 serotype dengue viral RNA were subsequently compared with those amplifying from the single serotypes dengue viral RNA. Results: By optimizing the reaction condition, four specific fragments (482,119,290,and 389 bp) were successfully amplified from the mixed RNA of 1-4 serotypes dengue viruses in single tube by single-tube nested multiple-PCR. Its sensitivity and specificity amplifying from the mixed RNA of 1-4 serotypes dengue viruses were similar to those amplifying from the single serotype dengue viral RNA. The detection limit of nested multiple-PCR was 66. 068 copies/μl. Conclusion: Single-tube nested multiple-PCR method is simple, rapid, sensitive, and specific for detecting and typing dengue viruses, and it is valuable for detecting and typing of the clinical multiple infections.
4. Genetic characteristics and deduced protein variation of nonstructural protein of novel influenza virus A/H1N1 in 2009 pandemic
Academic Journal of Second Military Medical University 2010;30(6):628-631
Objective: To elucidate the genetic characteristics and deduced protein variation of nonstructural protein (NS) gene of the novel influenza virus A/H1N1 in 2009 pandemic. Methods: The sequence of NS gene of A/H1N1 viruses isolated in North America, Europe, and Asia during 1930-2009 were downloaded from NCBI database. MEGA4.0 software and NJ method were used for sequence alignment, protein sequence alignment, and the phylogenetic tree construction. Results: The NS genes of novel influenza virus A/H1N1 in 2009 pandemic were originated from A/swine/H1N1 virus of 2005-2007; they shared a high homology of 97.5%-97.6%. There was an obvious evolutionary relationship between the NS genes of novel A/H1N1 virus and those of the influenza A/swine/H1N1 viruses isolated in North America from 1930 to 2007. No obvious changes were found in the amino acid sites for the antagonistic function of NS1 against the host antiviral capacity among these viruses. Conclusion: The NS gene of novel influenza virus A/H1N1 in 2009 pandemic might evolve from swine A/H1N1 influenza viruses isolated in the United States. The antagonistic function of NS1 against the host antiviral capacity is not changed.
10.Study on Vancomycin-resistant Enterococci Carried by Intestinal Tract in Different People Groups
Microbiology 1992;0(03):-
512?g/mL; MIC of 16 VIE to vancomycin were 16?g/mL; MIC of 8 VIE to vancomycin were 8?g/mL. It is a risk factor for hospital infection that VRE carriage of inpatients in intestinal tract is high. There is 100% agreement be-tween phenotypes and genotypes in 46 vancomycin resistance enterococci. VRE are multiresistant. Part iso-lates have high homology.