RESUMEN
AIMS: To exploit immunomagnetic separation combined with PCR with confronting two-pair primers (IMS-PCR-CTPP) as a rapid method for detection of Mycobacterium tuberculosis complex (MTC) and identification of Mycobacterium bovis from sputum specimens. METHODS AND RESULTS: Monoclonal antibody (mAb) against the mycobacterial antigen, 85B (Ag85B), was coupled with magnetic particles for specific immunomagnetic separation (IMS) of Mycobacterium spp. Immunofluorescence assay indicated the capability of mAb to bind to Ag85B in both the recombinant and the native form. The IMS combined with PCR-CTPP targeting the mycobacterial lep B gene was further implemented using 133 sputum samples with acid-fast bacilli grading from negative to 3+. The results showed the sensitivity and specificity of IMS-PCR-CTPP vs gold standard culture method were 89·9 and 88·6% respectively. CONCLUSIONS: The IMS-PCR-CTPP method shortens the time for tuberculosis (TB) diagnosis from months to a day. This method is also suitable for investigation of MTC and epidemiological study of Myco. bovis in sputum specimens. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first report emphasizing the combination of IMS and PCR-CTPP for the detection of MTC and simultaneous identification of Myco. bovis from sputum. It could be used for TB diagnosis in resource-limited countries with high TB burden.
Asunto(s)
Pruebas Diagnósticas de Rutina/métodos , Separación Inmunomagnética/métodos , Mycobacterium bovis/aislamiento & purificación , Mycobacterium tuberculosis/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Tuberculosis/microbiología , Cartilla de ADN/genética , Pruebas Diagnósticas de Rutina/instrumentación , Humanos , Separación Inmunomagnética/instrumentación , Mycobacterium bovis/clasificación , Mycobacterium bovis/genética , Mycobacterium tuberculosis/clasificación , Mycobacterium tuberculosis/genética , Reacción en Cadena de la Polimerasa/instrumentación , Sensibilidad y Especificidad , Esputo/microbiología , Tuberculosis/diagnósticoRESUMEN
To study genotype and phenotype correlation of haemophilia A in Thai patients, molecular defects of the factor VIII (FVIII) gene were examined and their correlation with clinical phenotypes were evaluated. The molecular pathologies of FVIII in Thai patients were found to be heterogeneous. The most common mutation was FVIII intron 22 inversion accounting for about 30% of the severe cases while gene deletion was rare. Sixteen point mutations were identified, comprising two nonsense mutations (R-5X and R1966X), five missense mutations (T233I, D542Y, G1850V, W2229S and G2325C), five nucleotide deletions (1145delT, 1187-8delACAC, 1191-4delA, 1458delGA and 1534delA), three nucleotide insertions (1439-41insA, 1934insTA and 2245insACTA) and one splicing defect (IVS15+1G>T). Nine mutations (T233I, D542Y, 1145delT, 1458delGA, 1534delA, 1934insTA, W2229S, 2245insACTA and G2325C) were novel, firstly identified in Thai patients. The genotypes were found to correlate with clinical phenotypes in a majority of cases. However, in five patients the molecular defects did not correlate with clinical severity and FVIII:C level. Cellular and molecular mechanisms were proposed to be responsible in amelioration of clinical severity caused by deleterious mutations. Carrier detection by direct mutation analysis was also demonstrated.
Asunto(s)
Factor VIII/genética , Hemofilia A/genética , Mutación , Análisis Mutacional de ADN , Femenino , Tamización de Portadores Genéticos , Genotipo , Humanos , Masculino , Linaje , Fenotipo , Mutación PuntualRESUMEN
Six frameshift mutations in exon 14 of the factor VIII gene were identified in Thai hemophilia A patients. Although all these mutations created premature stop codons and expected to cause severe disease, the molecular defects and clinical severity were in discrepancy in some patients. Four mutations (delT3490, delACAC3618-21, delGA4429-30, and delA4658) were found in the patients with the severe clinical phenotype while two (delA3629-37 and insA4372-9) were observed in the patients who had moderate severity, with FVIII:C of 4.2 and 2.8%. The frameshift mutations in these two patients were due to deletion and insertion of an 'A' nucleotide in the stretches of 9As and 8As in codons 1191-4 and 1439-41, respectively. This indicates that deletion or insertion in the stretches of poly A nucleotides in exon 14 of the factor VIII gene is a likely cause of the moderate clinical severity in some cases of Thai hemophilia A patients.