Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023241 (Legionella)
 6,990 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An electrochemical genosensor for the detection of nucleic acid sequences specific of Legionella pneumophila is reported. An immobilized thiolated hairpin probe is combined with a sandwich-type hybridization assay, using biotin as a tracer in the signaling probe, and streptavidin-alkaline phosphatase as reporter molecule. The activity of the immobilized enzyme was voltammetrically determined by measuring the amount of 1-naphthol generated after 2 min of enzymatic dephosphorylation of 1-naphthyl phosphate. The sensor allows discrimination between L. pneumophila and L. longbeachae with high sensitivity under identical assay conditions (no changes in stringency). A limit of detection of 340 pM L. pneumophila DNA, and a linear relationship between the analytical signal and the logarithm of the target concentration to 2 muM were obtained. Experimental results show the superior sensitivity and selectivity of the hairpin-based assay when compared with analogous sandwich-type assays using linear capture probes.
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PMID:Hairpin-DNA probe for enzyme-amplified electrochemical detection of Legionella pneumophila. 1747 3

Human infections with Legionella pneumophila represent a public health problem. Current culture assays for surveillance and control of L. pneumophila in water are time-consuming and limited by the sensitivity, especially when samples also contain microorganisms that inhibit Legionella growth. In this work, an electrochemical method, different from real-time polymerase chain reaction (PCR) approaches, for semiquantitative evaluation of L. pneumophila is presented. A PCR assay targeting the 16S-rRNA gene of L. pneumophila giving rise to a 95-mer amplicon was established. Amplicons were hybridized to a biotin-labeled reporter sequence and then to a thiolated stem-loop structure immobilized onto gold electrodes as a reporter molecule with 1-naphthyl phosphate as a substrate. 1-Naphthol enzymatically generated was determined by differential pulse voltammetry (DPV). For a constant number of amplification cycles, results show that the voltammetric signal is related to the number of copies in the sample thus achieving a useful semiquantitative estimation of L. pneumophila. After 40 cycles of PCR amplification this methodology has a limit of detection of 10 genomes, allowing the reliable detection of 10(2) genomes of L. pneumophila as well as distinguishing 10(3) and 10(4) genomes of the pathogen, values related to corrective actions in water systems in buildings, in accordance with the legislation currently in force.
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PMID:PCR-coupled electrochemical sensing of Legionella pneumophila. 1916 78