Interpretation of results obtained using real-time fluorescence PCR based on multiplex PCR fragment analysis for ABCB1 tri-allele / 四川精神卫生

ObjectiveTo resolve the problems related to the abnormal interpretations of real-time fluorescence polymerase chain reaction （PCR） results for tri-allele， to formulate the interpretation methods of real-time fluorescence PCR by referring to multiplex PCR fragment analysis， so as to obtain an accurate， simple and cheap detection method for ABCB1 tri-allele. MethodsA total of 2 794 DNA samples were collected from Xi'an Mental Health Center from March 2020 to March 2021， and 5% of which were selected as experiments. Real-time fluorescence PCR method and multiplex PCR fragment analysis method were performed respectively. According to the comparison of Ct values of PCR curves and the comparison of base peak intensity in multiplex PCR fragment analysis， comparison and analysis were conducted on the interpretation results of the two methods， and samples with different interpretation results were verified， thereafter， PCR interpretation method was formulated. ResultsA total of 139 samples were collected， of which 120 alleles and 19 tri-allele were detected. The results of allele detection by two methods were absolutely consistent. In combination with the results of multiplex PCR fragment analysis， a method for the interpretation of real-time fluorescence PCR for 19 cases of tri-allele was developed as follows： when ∣∣Ct.G－Ct.T∣－∣Ct.G－Ct.A∣∣ in amplification curve was less than 3， the interpretation results were the combination of the base pairs with small Ct values； when ∣∣Ct.G－Ct.T∣－∣Ct.G－Ct.A∣∣ was greater than or equal to 3， the interpretation results were homozygotes from the base pairs with minimum Ct values. According to the interpretation method， the results of real-time fluorescence PCR were revised， and it showed 1 case of G/G， 1 case of A/A， 4 cases of T/G， 5 cases of T/A and 8 cases of T/T， which were consistent with the results of multiplex PCR fragment analysis. ConclusionReferring to the multiplex PCR fragment analysis method， the interpretation of ABCB1 tri-allele by real-time fluorescence PCR is developed， and the two interpretation methods are in good agreement.

A real-time fluorescence quantitative PCR method for source identification of Crocus sativus and Carthamus tinctorius / 中国中药杂志

The specific PCR primer was designed base on ITS2 sequence in GenBank, and we developed a SYBRGreen real-time fluorescence quantitative PCR system for identification of Crocus sativus and Carthamus tinctorius source. Compared with Chinese herbal medicine DNA barcode technique, this method showed characteristics of shorter time, higher specificity and sensitivity. Using this method to detect 15 samples, 4 were C. sativus, 8 were C. tinctorius, and the other 3 samples were none of them. The result was in accordance with Chinese herbal medicine DNA barcode. This study lays the foundation for identification of related Chinese medical materials.

New EMA real-time fluorescence PCR method for detection of alive Listeria monocytogenes in foods / 中国人兽共患病学报

A new EMA real-time fluorescence PCR method was developed to detect alive Listeria monocytogenes in foods.The specific primers and probe were designed based on the conserved inlA gene.The pretreatment conditions including EMA of different concentrations and irradiating times were optimized.The detection limit and inhibition rate to dead bacteria of this method were confirmed by using direct plating method.The detection specificity was evaluated by using 35 L.monocytogenes strains,25 non-L.monocytogenes strains and 92 non-Listeria strains.Simulation detection experiments were performed on 15 beverage samples and 15 cooked meat samples supplemented separately with inactivated L.monocytogenes,alive L.monocytogenes and Staphylococcus aureus.Results showed that the Ct of EMA real-time fluorescence PCR for alive L.monocytogenes was Ct=38.46-3.30 × log (R2=0.999).The detection limit was 55 cfu per reaction.Inhibition rate of DNA of inactivated strains was over 99.98％.The Ct of 35 L.monocytogenes strains were between 16.21 and 29.38,while 25 non-L.monocytogenes strains and 92 non-Listeria strains had Ct ＞35.The variation coefficient of CT was less than 5％ when the experiments were repeated.Results of 30 simulation samples were consistent with that by using standard method.The test time by using newly developed EMA real-time fluorescence PCR was shortened from 3-5 days to about 10 h.The newly developed EMA real-time fluorescence PCR method for alive L.monocytogenes is rapid,convenient,specific and sensitive and could be applyed in foods inspection.

Study on the Quinolone Antibiotic Resistance and Its Relative Genes in Campylobacter Jejuni / 现代检验医学杂志

Objective To establish a real-time fluorescence PCR method to detect the drug resistance genes of pathogenic Campylobacter jejunum in human stool samples,and investigate the relationship between quinoloneantibiotic resistance and the related genes in Campylobacter jejuni .Methods According to the gyrA and gyrB gene sequences that related with the fluoroquinolone resistance in Campylobacter jejuni ,the primers of the PCR method was designed and synthesized.A rapid real-time fluorescence PCR method to detect the drug resistance genes in Campylobacter jejuni samples was established,and the optimum reaction system and conditions were screened through an optimized approach.The developed method was com-pared with the classical drug susceptibility assay.Results It was found in the compared results that,there were 8 inconsis-tent strains of Campylobacter jejuni ,2 of the 8 strains were drug sensitive but contented the drug resistance gene,while 6 strains were drug resistant but had no drug resistant gene.Conclusion The established method can be applied to detect the drug resistance relative genes of gyrA and gyrB in Campylobacter jejuni .There was some correlation between the drug re-sistance representation and its genotype,but this point requires further studies.

ApoE genotyping by real-time fluorescence PCR / 临床检验杂志

Objective To establish a new effective method by using real-time polymerase chain reaction (PCR) to detect single nucleotide polymorphism (SNP) typing for rapid identifying apolipoprotein E alleles.Methods To determine alleles of human apolipoprotein E genetic polymorphism at Cys112Arg locus was detected by PCR melting curve analysis with fluorophore SYBR Green I. In order to increase the speciality of SNP assays, high fidelity Taq polymerase was used. The reliability of SNP typing was validated by comparison with the results of direct DNA sequencing.Results Each sample was determined by double tubes, and two melting curves were analysis. As compared the Tm value of samples with the Tm of standard substance, the apoE genotype of samples was determined. The apoE genotype of 30 samples were E3/3 (27/30) and E3/4 (3/30) respectively, which was accordant with the results of PCR-RFLP and DNA sequencing.Conclusion The presented allelic assay was specific, easy to operate and applicable for discrimination of apolipoprotein E genotyping of human blood.