Rapid and Sensitive Detection of Yersinia pestis Using Amplification of Plague Diagnostic Bacteriophages Monitored by Real-Time PCR

BACKGROUND: Yersinia pestis, the agent of plague, has caused many millions of human deaths and still poses a serious threat to global public health. Timely and reliable detection of such a dangerous pathogen is of critical importance. Lysis by specific bacteriophages remains an essential method of Y. pestis detection and plague diagnostics. METHODOLOGY/PRINCIPAL FINDINGS: The objective of this work was to develop an alternative to conventional phage lysis tests--a rapid and highly sensitive method of indirect detection of live Y. pestis cells based on quantitative real-time PCR (qPCR) monitoring of amplification of reporter Y. pestis-specific bacteriophages. Plague diagnostic phages phiA1122 and L-413C were shown to be highly effective diagnostic tools for the detection and identification of Y. pestis by using qPCR with primers specific for phage DNA. The template DNA extraction step that usually precedes qPCR was omitted. phiA1122-specific qPCR enabled the detection of an initial bacterial concentration of 10(3) CFU/ml (equivalent to as few as one Y. pestis cell per 1-microl sample) in four hours. L-413C-mediated detection of Y. pestis was less sensitive (up to 100 bacteria per sample) but more specific, and thus we propose parallel qPCR for the two phages as a rapid and reliable method of Y. pestis identification. Importantly, phiA1122 propagated in simulated clinical blood specimens containing EDTA and its titer rise was detected by both a standard plating test and qPCR. CONCLUSIONS/SIGNIFICANCE: Thus, we developed a novel assay for detection and identification of Y. pestis using amplification of specific phages monitored by qPCR. The method is simple, rapid, highly sensitive, and specific and allows the detection of only live bacteria

Properties of GaAs/InGaAs Quantum-Size Structures Containing delta < Mn >-Doped Layers

Properties of structures containing an InGaAs quantum well (QW) or InAs quantum dots (QDs) as well as delta - and delta -doped layers are investigated. Most of these structures are fabricated by the MOCVD epitaxy method; delta -doped layers are obtained by low-temperature laser deposition directly in the epitaxial reactor. The structures under study exhibit three conduction channels: the delta -doped layer, delta -doped layer, and QW or wetting layer in the case of QDs. The contribution of each channel into the total conduction depend on the measurement temperature. Photoluminescence of the structures as a function of thickness of delta -doped layer is studied.116466CRDF [RUX0-001-NN-06/BP1M01]Russian Foundation for Basic Research [05-02-16624]CRDF [RUX0-001-NN-06/BP1M01]Russian Foundation for Basic Research [05-02-16624

Ferromagnetic semiconductor InMnAs layers grown by pulsed laser deposition on GaAs

status: publishe