Drug sensitivity testing to establish resistance to TB drugs takes many months to arrive at. Public health physicians have difficulties with such an approach due to long wait periods and cannot use it to establish com...Drug sensitivity testing to establish resistance to TB drugs takes many months to arrive at. Public health physicians have difficulties with such an approach due to long wait periods and cannot use it to establish community wide prevalence as a way to understand where resistance may be emerging faster and to limit its spread. The objective of this study was to use the dot-blot hybridization technique in the detection of resistance to rifamycin (RIF) and streptomycin (SM) in South- Western Cameroon and to compare the technique with the routine culture and drug susceptibility testing for detecting resistance in a resource poor country, Cameroon. A hospital-based study was conducted at the Regional hospitals of Buea and Limbe and Tiko Central Clinic. Tuberculosis (TB) patients aged 15 to 50 (mean age: 30.50 ± 8.33 standard deviation) were recruited for the study between December 2006 and April 2007. Cultures from 59 patients were tested for rifampicin and streptomycin sensitivity by the modified proportion method and mutational analysis for rpoB codon 516 and rrs codon 513 was performed by the dot-blot hybridization technique. Of the 59 sputum samples collected (36 were males and 23 were females) came from Buea 19 (32.2%), Limbe 20 (33.9%) and Tiko 20 (33.9%) towns respectively. Amplification for the gene showed that there was (59) 100% amplification with primers used for rpoB genes and 43 (72.9%) amplification with primers used for the rrs gene. Mutational analysis demonstrated that resistance to RIF was common in females (52.1%) than males (41.7%) while 6% of the samples were indeterminate. 12 (20.3%) samples showed phenotypic and genotypic resistance to RIF compared to 34 samples (58.1%) for SM. Phenotypic resistance and genotypic susceptibility were found in 5 (8.5%) RIF and 3 (4.7%) SM compared to phenotypic susceptibility and genotypic resistance that were found in 2 (3.5%) RIF and 3(4.7%) SM. Double mutation on rpoB and rrs genes occurred in 8 (13.6%) DNA samples. Resistance to RIF and SM due to mutations on the rpoB and rrs genes respectively in the SW region was found to be high and comparable to the drug susceptibility testing by 92%, (95% CI: 75.7 - 99.1). The Dot-blot technique will be useful in rapidly assessing the effectiveness of national TB control programs in limiting the spread of resistance strains in Cameroon.展开更多
Objective: To access the performance of the Tellgenplex human papillomavirus(HPV) DNA test compared to the polymerase chain reaction-reverse dot blot(PCR-RDB) assay for the HPV genotyping.Methods: Sixty cervical swab ...Objective: To access the performance of the Tellgenplex human papillomavirus(HPV) DNA test compared to the polymerase chain reaction-reverse dot blot(PCR-RDB) assay for the HPV genotyping.Methods: Sixty cervical swab samples were genotyped by the Tellgenplex HPV DNA test and the PCR-RDB assay.The Tellgenplex HPV DNA test and the PCR-RDB assay can detect 26 and 23 HPV genotypes, respectively.Each sample showed discrepancy was genotyped using sequencing.Results: The percent agreement between the two tests ranged from 83.3% to 100.0% according to different genotype.This showed perfect agreement(>0.81) for high-risk HPV genotypes(35, 39, 45, 53, 56, 59, 66, 68, and 82), substantial agreement(>0.65) for high-risk HPV genotypes(16, 18, 33, 52, and 58) and low-risk HPV genotype 43 between the two assays by the kappa analysis.The positive rates of the two assays for frequent HPV genotypes(16, 35, 39, 45, 52, 53, 58, 59, 66, and 82) were not statistically different, but the PCR-RDB assay showed higher positive rates than the Tellgenplex HPV DNA test for HPV genotypes 81(P<0.05).As for more than 10 positive results by the Tellgenplex HPV DNA test and/or the PCR-RDB assay, the PCR-RDB assay showed higher relative sensitivity and specificity than the Tellgenplex HPV DNA test for the three HPV genotypes(16, 52, and 81).All HPV genotypes that can be detected by only the Tellgenplex HPV DNA test(HPV genotypes 44 and 55) were confirmed by sequencing.Conclusions: In conclusion, our results demonstrated that the PCR-RDB assay which can detect more multiple HPV genotypes in each specimen shows higher relative sensitivity and specificity than the Tellgenplex HPV DNA test, which makes it a better option for routine clinical use.展开更多
Hypertrophic cardiomyopathy (HCM) is one of the diseases damaging people health most badly and some mutations of exons in cardiac troponin I (cTnI) gene are closely associated with family hypertrophic cardiomyopathy (...Hypertrophic cardiomyopathy (HCM) is one of the diseases damaging people health most badly and some mutations of exons in cardiac troponin I (cTnI) gene are closely associated with family hypertrophic cardiomyopathy (FHCM).A microarray was fabricated to screen mutations in exons 3,5,7,and 8 in cTnI gene.Primers were designed for the PCR (polymerase chain reaction) to amplify the target DNA fragments from fresh blood samples.In order to simplify the PCR process,multiplex PCR technology was investigated in detail.The concentration of Mg^(2+) played an important role in multiplex PCR process,a properly low concentration of Mg^(2+) submitted a better speciality of PCR products.The speciality was also favored when the annealing temperature was reasonably enhanced and 64℃is the optimal annealing temperature for the multiplex PCR systems.When applying the fabricated gene-chip to detect the target fragments from PCR mixture,the signal intensity sequence is in accordance with that from theoretic estimate.展开更多
Using the BrdU antibody technique followed by an immuno-chemical staining(BAT),the amplification o f DNA fragments specific to human Y chromosome on cell specimen slides was efficiently detected. Whether direct BrdU i...Using the BrdU antibody technique followed by an immuno-chemical staining(BAT),the amplification o f DNA fragments specific to human Y chromosome on cell specimen slides was efficiently detected. Whether direct BrdU incorporation into PCR products or in situ hybridization with PCR products on slides, the amplified targetDNA fragments of specimen were visualized by BAT under the microscope. The availability of BAT and differencesin the sensitivity and efficiency between BAT and dig--if-dUTP labeling in cell in situ PCR were disCussed.展开更多
The present study reports an improved PCR-based technique that allows quick and effective screening of cDNA libraries. First, the cDNA library was arrayed as follow: about 3 X 10’ cDNA clones were multiplied as indiv...The present study reports an improved PCR-based technique that allows quick and effective screening of cDNA libraries. First, the cDNA library was arrayed as follow: about 3 X 10’ cDNA clones were multiplied as individual plaques on solid medium in 24-well culture dishes at 1 200 plaque forming units per well. The phage suspension of each well was transferred to an individual microcentrifuge tube in 72-tube box. Then, box pool, row pools and column pools were set up that respectively represent a 72-tube box, rows and columns within the box. To screen a specific target cDNA,primers specific for novel ESTs ob- tained in our laboratory were employed to conduct PCR in a hierarchy mode. PCR began with the box pools, resulting in the identification of some Positive box pools. Then PCR went down to the row and col- umn pools of the positive box. The intersection of the positive row (s) and column (s) revealed the candi- date positive tubes. The specificity of PCR products were meanwhile checked by restriction enzyme diges- tion. Finally, hybridization was carried out to get single specific cDNA clomes from the positive tubes. This PCR-based technique features high specificity, high efficiency and less-cost in large-scale cDNA library screening. Our initial implementation of the technique resulted in the isolation of three longer different cD- NA clones from a human fetal brain cDNA library. Thus this improved technique can serve as an alterna-tive to the time-consuming and laborious conventional hybridization-based method for screening cDNA li-brary.展开更多
[Objectives]To establish a simple,rapid and accurate method for identifying the genetic relationship of hybrid rice varieties to their parents.[Methods]Taking F1 hybrids Liangyou 336,Deliangyou Huazhan,and the parents...[Objectives]To establish a simple,rapid and accurate method for identifying the genetic relationship of hybrid rice varieties to their parents.[Methods]Taking F1 hybrids Liangyou 336,Deliangyou Huazhan,and the parents of Liangyou 336,i.e.,C815S(♀)and R336(♂),as experimental materials,the genetic relationship of the hybrid rice varieties to the parental materials was identified by way of PCR amplification with the 48 pairs of SSR primers of Protocol for Identification of Rice Varieties:SSR Marker Method(NY/T 1433-2014).[Results]The genetic relationship of the hybrid rice varieties could be determined by comparing the PCR amplification products of the mixed DNA of the parents and the DNA of the F1 hybrids.[Conclusions]This method not only reduced the number of samples required but also had a good visual effect and high accuracy.展开更多
In this paper, we developed a rapid and accurate method for the detection of Vibrio parahaemolyticus strains, using multiplex PCR and DNA--DNA hybridization. Multiplex PCR was used to simultaneously amplify three diag...In this paper, we developed a rapid and accurate method for the detection of Vibrio parahaemolyticus strains, using multiplex PCR and DNA--DNA hybridization. Multiplex PCR was used to simultaneously amplify three diagnostic genes (tlh, tdh andfla) that serve as molecular markers of V. parahaemolyticus. Biotinylated PCR products were hybridized to primers immobilized on a microarray, and detected by chemiluminesce with avidin-conjugated alkaline phosphatase. With this method, forty-five samples were tested. Eight known virulent strains (tlh+/tdh+/fla+) and four known avirulent strains (tlh+/tdh /fla+) of the V. parahaemolyticus were successfully detected, and no non-specific hybridization and cross-hybridization reaction were found from fifteen closely-related strains (tlh-/tdh-/fla+) of the Vibrio spp. In addition, all the other eighteen strains of non-Vibrio bacteria (tlh-/tdh /fla-) gave negative results. The DNA microarray successfully distinguished V. parahaemolyticus from other Vibrio spp. The results demonstrated that this was an efficient and robust method for identifying virulent strains of V. parahaemolyticus.展开更多
PCR enzyme linked immune sorbent assay (ELISA) was developed for detection of RT PCR amplified cytokeratin 19 (CK19) mRNA and carcinoembryonic antigen (CEA) mRNA. The non radioactive hybridization was performed in ...PCR enzyme linked immune sorbent assay (ELISA) was developed for detection of RT PCR amplified cytokeratin 19 (CK19) mRNA and carcinoembryonic antigen (CEA) mRNA. The non radioactive hybridization was performed in a streptavidin coated microwell with digoxigenin labeled PCR products and with biotin labeled capture probe. PCR ELISA was proved to be expedient, simple, sensitive and safe for identification of CK19 , CEA RT PCR products. These results were proven by sequencing.展开更多
Formalin-fixed paraffin-embedded tissue,including gallbladder,kidney,spleen,adrenal gland,heart,testicle,pancreas,and liver from 18 autopsied cases with HBV infection were studied with nested polymerase chain reaction
Dot-blot hybridization was applied in this paper to detect five viruses infecting cucurbitaceous crops, Zuccini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Cucumber mosaic virus (CMV), Papaya ring...Dot-blot hybridization was applied in this paper to detect five viruses infecting cucurbitaceous crops, Zuccini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Cucumber mosaic virus (CMV), Papaya ringspot viruswatermelon strain (PRSV-W) and Squash mosaic virus (SqMV), as a good alternative assay in seed health test and epidemiological and transgenic research. Digoxigenin-labelled cDNA probes of the five viruses were synthesized by PCR with the specific primers and applied in dot-blot hybridization to detect five viruses in crude extraction of the infected leaves. And three SqMV probes of different lengths (0.55, 1.6, and 2.7 kb, respectively) were designed to investigate the effect of hybridization. The results showed that the sensitivity for detecting the crude extraction of infected leaves by ZYMV, WMV, CMV, PRSV-W, and SqMV was down to 1:160, 1:160, 1:320, 1:160, and 1:320, respectively. Three SqMV probes of different length showed no differences on the sensitivity and specificity. The digoxigenin-labelled probes prepared by PCR could be used for accurate and rapid identification of 5 viruses infecting cucurbitaceous crops with good stabilities, sensitivities, specificity, and reproducibilifies.展开更多
Objective A PCR-reverse dot blot hybridization (RDBH) assay was developed for rapid detection of rpoB gene mutations in 'hot mutation region' of Mycobacterium tuberculosis (M. tuberculosis). Methods 12 oligonucl...Objective A PCR-reverse dot blot hybridization (RDBH) assay was developed for rapid detection of rpoB gene mutations in 'hot mutation region' of Mycobacterium tuberculosis (M. tuberculosis). Methods 12 oligonucleotide probes based on the wild-type and mutant genotype rpoB sequences of M. tuberculosis were designed to screen the most frequent wild-type and mutant genotypes for diagnosing RIF resistance. 300 M. tuberculosis clinical isolates were detected by RDBH, conventional drug-susceptibility testing (DST) and DNA sequencing to evaluate the RDBH assay. Results The sensitivity and specificity of the RDBH assay were 91.2% (165/181) and 98.3% (117/119), respectively, as compared to DST. When compared with DNA sequencing, the accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the RDBH assay were 97.7% (293/300), 98.2% (164/167), and 97.0% (129/133), respectively. Furthermore, the results indicated that the most common mutations were in codons 531 (48.6%), 526 (25.4%), 516 (8.8%), and 511 (6.6%), and the combinative mutation rate was 15 (8.3%). One and two strains of insertion and deletion were found among all strains, respectively. Conclusion Our findings demonstrate that the RDBH assay is a rapid, simple and sensitive method for diagnosing RIF-resistant tuberculosis.展开更多
The relationship between embB mutation of Mycobacterium tuberculosis and ethambutol (EMB) resistance of the clinical isolates of tuberculous patients in China was investigated by reverse dot blot hybridization (RDBH) ...The relationship between embB mutation of Mycobacterium tuberculosis and ethambutol (EMB) resistance of the clinical isolates of tuberculous patients in China was investigated by reverse dot blot hybridization (RDBH) in addition to evaluating the clinical value with application of PCR-RDBH technique to detect EMB resistance. In the present study, the genotypes of the 258 bp fragments of embB genes from 196 clinical isolates of M. tuberculosis were analysed with RDBH and DNA sequencing. It was demonstrated that 60 out of 91 phenotypically EMB-resistant isolates (65.9%) showed 5 types of missense mutations at codon 306 of embB gene, resulting in the replacement of the Met residue of the wild type strain with Val, Ile or Leu residues. In these mutations, the GTP mutation (38/91, 41.8%) and the ATA mutation (16/91, 17.6%) were the most encountered genotypes. The embB mutation at codon 306 could also be found in 69 isolates of phenotypically EMB-sensitive but resistant to other anti-tuberculous drugs, but no such gene mutation could be found in 36 strains of drug-sensitive isolates. Meanwhile, the concordance with the results of DNA sequencing for one wide-type probe and 5 probes for specific mutations was 100% . It was concluded that the EMB-resistance occurring in most M. tuberculosis is due to appearance of embB mutation at codon 306, and the PCR-RDBH assay was proved to be a rapid, simple and reliable method for the detection of gene mutations, which might be a good alternative for the drug-resistance screening.展开更多
文摘Drug sensitivity testing to establish resistance to TB drugs takes many months to arrive at. Public health physicians have difficulties with such an approach due to long wait periods and cannot use it to establish community wide prevalence as a way to understand where resistance may be emerging faster and to limit its spread. The objective of this study was to use the dot-blot hybridization technique in the detection of resistance to rifamycin (RIF) and streptomycin (SM) in South- Western Cameroon and to compare the technique with the routine culture and drug susceptibility testing for detecting resistance in a resource poor country, Cameroon. A hospital-based study was conducted at the Regional hospitals of Buea and Limbe and Tiko Central Clinic. Tuberculosis (TB) patients aged 15 to 50 (mean age: 30.50 ± 8.33 standard deviation) were recruited for the study between December 2006 and April 2007. Cultures from 59 patients were tested for rifampicin and streptomycin sensitivity by the modified proportion method and mutational analysis for rpoB codon 516 and rrs codon 513 was performed by the dot-blot hybridization technique. Of the 59 sputum samples collected (36 were males and 23 were females) came from Buea 19 (32.2%), Limbe 20 (33.9%) and Tiko 20 (33.9%) towns respectively. Amplification for the gene showed that there was (59) 100% amplification with primers used for rpoB genes and 43 (72.9%) amplification with primers used for the rrs gene. Mutational analysis demonstrated that resistance to RIF was common in females (52.1%) than males (41.7%) while 6% of the samples were indeterminate. 12 (20.3%) samples showed phenotypic and genotypic resistance to RIF compared to 34 samples (58.1%) for SM. Phenotypic resistance and genotypic susceptibility were found in 5 (8.5%) RIF and 3 (4.7%) SM compared to phenotypic susceptibility and genotypic resistance that were found in 2 (3.5%) RIF and 3(4.7%) SM. Double mutation on rpoB and rrs genes occurred in 8 (13.6%) DNA samples. Resistance to RIF and SM due to mutations on the rpoB and rrs genes respectively in the SW region was found to be high and comparable to the drug susceptibility testing by 92%, (95% CI: 75.7 - 99.1). The Dot-blot technique will be useful in rapidly assessing the effectiveness of national TB control programs in limiting the spread of resistance strains in Cameroon.
基金supported by the National Nature Science Foundation of China,Grant Number:81400639the Science Foundation for Youth Scientists of the Second People’s Hospital of Guangdong Province of China,Grant Number:YQ2015-002
文摘Objective: To access the performance of the Tellgenplex human papillomavirus(HPV) DNA test compared to the polymerase chain reaction-reverse dot blot(PCR-RDB) assay for the HPV genotyping.Methods: Sixty cervical swab samples were genotyped by the Tellgenplex HPV DNA test and the PCR-RDB assay.The Tellgenplex HPV DNA test and the PCR-RDB assay can detect 26 and 23 HPV genotypes, respectively.Each sample showed discrepancy was genotyped using sequencing.Results: The percent agreement between the two tests ranged from 83.3% to 100.0% according to different genotype.This showed perfect agreement(>0.81) for high-risk HPV genotypes(35, 39, 45, 53, 56, 59, 66, 68, and 82), substantial agreement(>0.65) for high-risk HPV genotypes(16, 18, 33, 52, and 58) and low-risk HPV genotype 43 between the two assays by the kappa analysis.The positive rates of the two assays for frequent HPV genotypes(16, 35, 39, 45, 52, 53, 58, 59, 66, and 82) were not statistically different, but the PCR-RDB assay showed higher positive rates than the Tellgenplex HPV DNA test for HPV genotypes 81(P<0.05).As for more than 10 positive results by the Tellgenplex HPV DNA test and/or the PCR-RDB assay, the PCR-RDB assay showed higher relative sensitivity and specificity than the Tellgenplex HPV DNA test for the three HPV genotypes(16, 52, and 81).All HPV genotypes that can be detected by only the Tellgenplex HPV DNA test(HPV genotypes 44 and 55) were confirmed by sequencing.Conclusions: In conclusion, our results demonstrated that the PCR-RDB assay which can detect more multiple HPV genotypes in each specimen shows higher relative sensitivity and specificity than the Tellgenplex HPV DNA test, which makes it a better option for routine clinical use.
文摘Hypertrophic cardiomyopathy (HCM) is one of the diseases damaging people health most badly and some mutations of exons in cardiac troponin I (cTnI) gene are closely associated with family hypertrophic cardiomyopathy (FHCM).A microarray was fabricated to screen mutations in exons 3,5,7,and 8 in cTnI gene.Primers were designed for the PCR (polymerase chain reaction) to amplify the target DNA fragments from fresh blood samples.In order to simplify the PCR process,multiplex PCR technology was investigated in detail.The concentration of Mg^(2+) played an important role in multiplex PCR process,a properly low concentration of Mg^(2+) submitted a better speciality of PCR products.The speciality was also favored when the annealing temperature was reasonably enhanced and 64℃is the optimal annealing temperature for the multiplex PCR systems.When applying the fabricated gene-chip to detect the target fragments from PCR mixture,the signal intensity sequence is in accordance with that from theoretic estimate.
文摘Using the BrdU antibody technique followed by an immuno-chemical staining(BAT),the amplification o f DNA fragments specific to human Y chromosome on cell specimen slides was efficiently detected. Whether direct BrdU incorporation into PCR products or in situ hybridization with PCR products on slides, the amplified targetDNA fragments of specimen were visualized by BAT under the microscope. The availability of BAT and differencesin the sensitivity and efficiency between BAT and dig--if-dUTP labeling in cell in situ PCR were disCussed.
基金National Natural Science Fund!(39392900 ) 863 High-tech Project Fund of China!(102-10-03-02 )
文摘The present study reports an improved PCR-based technique that allows quick and effective screening of cDNA libraries. First, the cDNA library was arrayed as follow: about 3 X 10’ cDNA clones were multiplied as individual plaques on solid medium in 24-well culture dishes at 1 200 plaque forming units per well. The phage suspension of each well was transferred to an individual microcentrifuge tube in 72-tube box. Then, box pool, row pools and column pools were set up that respectively represent a 72-tube box, rows and columns within the box. To screen a specific target cDNA,primers specific for novel ESTs ob- tained in our laboratory were employed to conduct PCR in a hierarchy mode. PCR began with the box pools, resulting in the identification of some Positive box pools. Then PCR went down to the row and col- umn pools of the positive box. The intersection of the positive row (s) and column (s) revealed the candi- date positive tubes. The specificity of PCR products were meanwhile checked by restriction enzyme diges- tion. Finally, hybridization was carried out to get single specific cDNA clomes from the positive tubes. This PCR-based technique features high specificity, high efficiency and less-cost in large-scale cDNA library screening. Our initial implementation of the technique resulted in the isolation of three longer different cD- NA clones from a human fetal brain cDNA library. Thus this improved technique can serve as an alterna-tive to the time-consuming and laborious conventional hybridization-based method for screening cDNA li-brary.
基金Agricultural Science and Technology Innovation Fund of Hunan Province(2019LS06).
文摘[Objectives]To establish a simple,rapid and accurate method for identifying the genetic relationship of hybrid rice varieties to their parents.[Methods]Taking F1 hybrids Liangyou 336,Deliangyou Huazhan,and the parents of Liangyou 336,i.e.,C815S(♀)and R336(♂),as experimental materials,the genetic relationship of the hybrid rice varieties to the parental materials was identified by way of PCR amplification with the 48 pairs of SSR primers of Protocol for Identification of Rice Varieties:SSR Marker Method(NY/T 1433-2014).[Results]The genetic relationship of the hybrid rice varieties could be determined by comparing the PCR amplification products of the mixed DNA of the parents and the DNA of the F1 hybrids.[Conclusions]This method not only reduced the number of samples required but also had a good visual effect and high accuracy.
基金financial supports from National High Technology Research and Development Program of China(No.2007AA10Z430)National Natural Science Foundation of China(No.30700535)Program for New Century Excellent Talents in Fujian Province University,and Fok Ying Tong Education Foundation(No.111032)
文摘In this paper, we developed a rapid and accurate method for the detection of Vibrio parahaemolyticus strains, using multiplex PCR and DNA--DNA hybridization. Multiplex PCR was used to simultaneously amplify three diagnostic genes (tlh, tdh andfla) that serve as molecular markers of V. parahaemolyticus. Biotinylated PCR products were hybridized to primers immobilized on a microarray, and detected by chemiluminesce with avidin-conjugated alkaline phosphatase. With this method, forty-five samples were tested. Eight known virulent strains (tlh+/tdh+/fla+) and four known avirulent strains (tlh+/tdh /fla+) of the V. parahaemolyticus were successfully detected, and no non-specific hybridization and cross-hybridization reaction were found from fifteen closely-related strains (tlh-/tdh-/fla+) of the Vibrio spp. In addition, all the other eighteen strains of non-Vibrio bacteria (tlh-/tdh /fla-) gave negative results. The DNA microarray successfully distinguished V. parahaemolyticus from other Vibrio spp. The results demonstrated that this was an efficient and robust method for identifying virulent strains of V. parahaemolyticus.
文摘PCR enzyme linked immune sorbent assay (ELISA) was developed for detection of RT PCR amplified cytokeratin 19 (CK19) mRNA and carcinoembryonic antigen (CEA) mRNA. The non radioactive hybridization was performed in a streptavidin coated microwell with digoxigenin labeled PCR products and with biotin labeled capture probe. PCR ELISA was proved to be expedient, simple, sensitive and safe for identification of CK19 , CEA RT PCR products. These results were proven by sequencing.
文摘Formalin-fixed paraffin-embedded tissue,including gallbladder,kidney,spleen,adrenal gland,heart,testicle,pancreas,and liver from 18 autopsied cases with HBV infection were studied with nested polymerase chain reaction
文摘Dot-blot hybridization was applied in this paper to detect five viruses infecting cucurbitaceous crops, Zuccini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Cucumber mosaic virus (CMV), Papaya ringspot viruswatermelon strain (PRSV-W) and Squash mosaic virus (SqMV), as a good alternative assay in seed health test and epidemiological and transgenic research. Digoxigenin-labelled cDNA probes of the five viruses were synthesized by PCR with the specific primers and applied in dot-blot hybridization to detect five viruses in crude extraction of the infected leaves. And three SqMV probes of different lengths (0.55, 1.6, and 2.7 kb, respectively) were designed to investigate the effect of hybridization. The results showed that the sensitivity for detecting the crude extraction of infected leaves by ZYMV, WMV, CMV, PRSV-W, and SqMV was down to 1:160, 1:160, 1:320, 1:160, and 1:320, respectively. Three SqMV probes of different length showed no differences on the sensitivity and specificity. The digoxigenin-labelled probes prepared by PCR could be used for accurate and rapid identification of 5 viruses infecting cucurbitaceous crops with good stabilities, sensitivities, specificity, and reproducibilifies.
基金funded by the projects 2013ZX10003002-001 and 2013ZX10003006-002-001 of Chinese National Key Program of Mega Infectious Disease of the National 12th Five-Year Plan
文摘Objective A PCR-reverse dot blot hybridization (RDBH) assay was developed for rapid detection of rpoB gene mutations in 'hot mutation region' of Mycobacterium tuberculosis (M. tuberculosis). Methods 12 oligonucleotide probes based on the wild-type and mutant genotype rpoB sequences of M. tuberculosis were designed to screen the most frequent wild-type and mutant genotypes for diagnosing RIF resistance. 300 M. tuberculosis clinical isolates were detected by RDBH, conventional drug-susceptibility testing (DST) and DNA sequencing to evaluate the RDBH assay. Results The sensitivity and specificity of the RDBH assay were 91.2% (165/181) and 98.3% (117/119), respectively, as compared to DST. When compared with DNA sequencing, the accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the RDBH assay were 97.7% (293/300), 98.2% (164/167), and 97.0% (129/133), respectively. Furthermore, the results indicated that the most common mutations were in codons 531 (48.6%), 526 (25.4%), 516 (8.8%), and 511 (6.6%), and the combinative mutation rate was 15 (8.3%). One and two strains of insertion and deletion were found among all strains, respectively. Conclusion Our findings demonstrate that the RDBH assay is a rapid, simple and sensitive method for diagnosing RIF-resistant tuberculosis.
文摘The relationship between embB mutation of Mycobacterium tuberculosis and ethambutol (EMB) resistance of the clinical isolates of tuberculous patients in China was investigated by reverse dot blot hybridization (RDBH) in addition to evaluating the clinical value with application of PCR-RDBH technique to detect EMB resistance. In the present study, the genotypes of the 258 bp fragments of embB genes from 196 clinical isolates of M. tuberculosis were analysed with RDBH and DNA sequencing. It was demonstrated that 60 out of 91 phenotypically EMB-resistant isolates (65.9%) showed 5 types of missense mutations at codon 306 of embB gene, resulting in the replacement of the Met residue of the wild type strain with Val, Ile or Leu residues. In these mutations, the GTP mutation (38/91, 41.8%) and the ATA mutation (16/91, 17.6%) were the most encountered genotypes. The embB mutation at codon 306 could also be found in 69 isolates of phenotypically EMB-sensitive but resistant to other anti-tuberculous drugs, but no such gene mutation could be found in 36 strains of drug-sensitive isolates. Meanwhile, the concordance with the results of DNA sequencing for one wide-type probe and 5 probes for specific mutations was 100% . It was concluded that the EMB-resistance occurring in most M. tuberculosis is due to appearance of embB mutation at codon 306, and the PCR-RDBH assay was proved to be a rapid, simple and reliable method for the detection of gene mutations, which might be a good alternative for the drug-resistance screening.