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We analyzed genetic evolution characteristics of avian influenza A (H7N9) virus isolated in Zhaoqing,China,2014-2016.Nucleic acid were extracted and sequenced from 17 samples of H7N9 positive cases in Zhaoqing.Genetic characteristics of homology and important amino acid sites were analyzed by using BioEdit5.0 and MEGA6.0.The evolutionary trees were constructed by Neighbor-Joining and the referenced sequences were downloaded from GenBank,Eight nucleic acid fragments from 7 strains of H7N9 viruses were successfully generated.The highest homology was found in HA gene with A/chicken/Dongguan/695/2014(H7N9),and NA gene with A/chicken/Dongguan/1075/2014(H7N9).The internal genes were high homology with avian H7N9 and H9N2 virus from Dongguan and Shenzhen in Guangdong,China.The HA and NA genes were directly evolved in the Pearl River Delta evolution branch with the H7N9 sequences from the cities of Dongguan,Guangzhou and Shenzhen,while the sequences from the provinces of Anhui,Zhejiang,and Jiangsu were in the Yangtze River Delta evolution branch.There were 2 alkaline amino acids in cleavage site of HA,2 mutations (G186V and Q226L) in the crucial sites related with the receptor of HA protein,1 mutation (E627K) in PB2 protein,and 1 drug resistance mutation (S31N) in M2 protein.And no evidence of neuraminidase resistance in NA protein was found.In conclusion,the H7N9 virus for human infection in Zhaoqing may originate from avian H7N9 and H9N2 viruses,which circulated in the Pearl River Delta region of Guangdong from 2013 to 2014.The mutations of G186V,Q226L and E627 K might be related with high susceptibility to human beings.
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Objective@#To establish a TaqMan-MGB probe-based real-time fluorescence RT-PCR assay for avian influenza H5N6 virus used in rapid diagnosis for suspected cases and surveillance for outer environment of live poultry markets.@*Methods@#Based on the conservative sequences of avian influenza H5N6 virus for HA and NA gene published on GenBank, specific primers and TaqMan-MGB probes were designed to develop and optimize for the dual real-time RT-PCR assay. Specificity, sensitivity, repeatability and comparison tests were carried out.@*Results@#This dual real-time RT-PCR detection can be completed within 80 minutes. There was no cross-reaction with other subtypes of influenza virus and common respiratory pathogens. The minimum detection limit could be up to 10 copies/reaction. The correlation coefficient of standard curve for the gene of H5 and N6 were 0.999 and 0.993, and the coefficients of variation for cycle threshold were range from 0.151%-0.549%and 0.213%-0.575%, respectively. The positive and negative coincidence rates of the validation test were 100%.@*Conclusions@#This TaqMan-MGB probe-based dual real-time RT-PCR for avian influenza H5N6 virus was rapid, specific and sensitive. It will have a good use in early emergency detection of suspected cases and continuous monitoring of external environment in live poultry trade market.
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Objective To investigate the clinical value of PCR method for rapid screening Salmonella/Shigella in health physical examination .Methods A total of 3256 cases who were taken health physical examination from July 2011 to June 2015 ,were select-ed as the research object .Real-time fluorescence quantitative PCR method and the culture method were used for detecting Salmonel-la/Shigella ,and two methods were compared on their strengths and weaknesses for screening Salmonella/Shigella .Results A total of 46 cases with Salmonella were detected by PCR ,and the ratio was 1 .41% ;41 cases with Salmonella were detected by traditional culture method ,and the ratio was 1 .26% .39 cases with Shigella were detected by PCR and ,the ratio was 1 .20% ;32 cases were de-tected by traditional culture method ,and the ratio was 0 .98% .The difference was statistically significant (P<0 .05) .Sensitivity and specificity of PCR to detect Salmonella were 100 .00% and 99 .84% ,respectively ,and sensitivity and specificity of PCR to detect Shigella were 100 .00% and 99 .78% ,respectively .The PCR method is better than the traditional culture method concerning man-power ,processing time ,and satisfaction of test-takers ,and the cost of PCR method is significantly higher than that of traditional culture ,with a significant difference (P<0 .05) .PCR method contains high technology and has strong objectivity .Conclusion Real time fluorescent quantitative PCR method ,with high efficiency ,can be employed well for screening intestinal tract pathogenic bacte-ria ,improve the detection rate and accuracy for detecting Shigella and Salmonella ,and save time and energy as well .
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Objective To understand the gene E sequences of prevalent strains of Dengue fever type Ⅰ virus in Zhaoqing City during 2014.Methods The medical record data and acute stage serum of the patients with Dengue fever in Zhaoqing City during 2014 were collected.Dengue virus was cultured and isolated by using the C6/36 cell culture.Gene E of positive strains was amplified with RT-PCR.The phylogenetic tree was drawn and the bioinformatics analysis was conducted.Results Of 36 samples,20 samples were positive in viral isolation and culture.The gene E sequences of 20 strains of type Ⅰ Dengue virus prevalence in Zhaoqing dur-ing 2014 were obtained;the homology of these sequences was close to that of the 2 prevalent strains found in Zhongshan City,but was distant from that found in Guangzhou City.Conclusion The epidemic situation of Dengue fever in Zhaoqing City is closely re-lated to the prevalence situation of Zhongshan and is characterized by imported prevalence.