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Jiang J.,Naval Medical Research Center | You B.J.,Naval Medical Research Center | Liu E.,Naval Medical Research Center | Apte A.,Naval Medical Research Center | And 17 more authors.
Ticks and Tick-borne Diseases | Year: 2012

A previous surveillance study of human pathogens within ticks collected in the country of Georgia showed a relatively high infection rate for Rickettsia raoultii, R. slovaca, and R. aeschlimannii. These 3 spotted fever group rickettsiae are human pathogens: R. raoultii and R. slovaca cause tick-borne lymphadenopathy (TIBOLA), and R. aeschlimannii causes an infection characterized by fever and maculopapular rash. Three quantitative real-time polymerase chain reaction (qPCR) assays, Rraoul, Rslov, and Raesch were developed and optimized to detect R. raoultii, R. slovaca, and R. aeschlimannii, respectively, by targeting fragments of the outer membrane protein B gene (ompB) using species-specific molecular beacon or TaqMan probes. The 3 qPCR assays showed 100% specificity when tested against a rickettsiae DNA panel (n= 20) and a bacteria DNA panel (n= 12). The limit of detection was found to be at least 3 copies per reaction for all assays. Validation of the assays using previously investigated tick nucleic acid preparations, which included Rickettsia-free tick samples, tick samples that contain R. raoultii, R. slovaca, R. aeschlimannii, and other Rickettsia spp., gave 100% sensitivity for all 3 qPCR assays. In addition, a total of 65 tick nucleic acid preparations (representing 259 individual ticks) collected from the country of Georgia and the Republic of Azerbaijan in 2009 was tested using the 3 qPCR assays. R. raoultii, R. slovaca, and R. aeschlimannii were not detected in any ticks (n= 31) from the Republic of Azerbaijan, but in the ticks from the country of Georgia (n= 228) the minimal infection rate for R. raoultii and R. slovaca in Dermacentor marginatus was 10% and 4%, respectively, and for R. aeschlimannii in Haemaphysalis sulcata and Hyalomma spp. it was 1.9% and 20%, respectively. © 2012. Source


Rajanna C.,University of Florida | Ouellette G.,U.S. Army | Ouellette G.,SAIC | Ouellette G.,U.S. Department of Agriculture | And 16 more authors.
FEMS Microbiology Letters | Year: 2013

We describe here a strain of Yersinia pestis, G1670A, which exhibits a baseline mutation rate elevated 250-fold over wild-type Y. pestis. The responsible mutation, a C to T substitution in the mutS gene, results in the transition of a highly conserved leucine at position 689 to arginine (mutS(L689R)). When the MutSL689R protein of G1670A was expressed in a ΔmutS derivative of Y. pestis strain EV76, mutation rates observed were equivalent to those observed in G1670A, consistent with a causal association between the mutS mutation and the mutator phenotype. The observation of a mutator allele in Yersinia pestis has potential implications for the study of evolution of this and other especially dangerous pathogens. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. Source

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