Browsing by Author "Martinez Valdebenito, Constanza"

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    Detection of Rickettsia andeanae in two regions of Chile
    (SOC CHILENA INFECTOLOGIA, 2013) Abarca, Katia; Lopez, Javier; Acosta Jamett, Gerardo; Martinez Valdebenito, Constanza
    Introduction: Candidatus 'Rickettsia andeanae' is recently recognized specie, with no attributed pathogenic role so far. It has been reported in Amblyomma ticks from Peru, USA and Argentina, and recently in Chile, in one specimen of Amblyomma triste from a rural locality in Arica. Objective: To determine the presence of rickettsial agents in ticks from domestic dogs from two Chilean regions. Methods: A transversal descriptive study in Coquimbo and Araucania regions, Consisted in households sampling in the cities of Coquimbo and Angol and nearby rural localities, in spring-summer 2011-2012. One clog per house was examined and ticks Were collected when present; after taxonomic identification, gltA and ompA genes were amplified and sequenced. Results: 462 dogs were examined, 255 had ticks (55%). In the cities just Rhipicephalus sanguineus was found; in rural localities also Amblyomma tigrinum. Obtained sequences in 12 specimens from A. tigrinum corresponded to Candidatus 'Rickettsia andeanae'. Conclusions: We documented the presence of R. andeanae in two distant Chilean regions, which is added to its recently finding in the Northern extreme of the country. This new rickettsial agent limits to Amblyomma ticks and rural areas, as it was reported in other American countries and corresponds with this tick habitat.
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    Development and Characterization of a Highly Specific and Sensitive SYBR Green Reverse Transcriptase PCR Assay for Detection of the 2009 Pandemic H1N1 Influenza Virus on the Basis of Sequence Signatures
    (AMER SOC MICROBIOLOGY, 2011) Medina, Rafael A.; Rojas, Mark; Tuin, Astrid; Huff, Stephen; Ferres, Marcela; Martinez Valdebenito, Constanza; Godoy, Paula; Garcia Sastre, Adolfo; Fofanov, Yuriy; SantaLucia, John, Jr.
    The emergence and rapid spread of the 2009 H1N1 pandemic influenza virus showed that many diagnostic tests were unsuitable for detecting the novel virus isolates. In most countries the probe-based TaqMan assay developed by the U.S. Centers for Disease Control and Prevention was used for diagnostic purposes. The substantial sequence data that became available during the course of the pandemic created the opportunity to utilize bioinformatics tools to evaluate the unique sequence properties of this virus for the development of diagnostic tests. We used a comprehensive computational approach to examine conserved 2009 H1N1 sequence signatures that are at least 20 nucleotides long and contain at least two mismatches compared to any other known H1N1 genome. We found that the hemagglutinin (HA) and neuraminidase (NA) genes contained sequence signatures that are highly conserved among 2009 H1N1 isolates. Based on the NA gene signatures, we used Visual-OMP to design primers with optimal hybridization affinity and we used ThermoBLAST to minimize amplification artifacts. This procedure resulted in a highly sensitive and discriminatory 2009 H1N1 detection assay. Importantly, we found that the primer set can be used reliably in both a conventional TaqMan and a SYBR green reverse transcriptase (RT)-PCR assay with no loss of specificity or sensitivity. We validated the diagnostic accuracy of the NA SYBR green assay with 125 clinical specimens obtained between May and August 2009 in Chile, and we showed diagnostic efficacy comparable to the CDC assay. Our approach highlights the use of systematic computational approaches to develop robust diagnostic tests during a viral pandemic.
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    Parotiditis en Chile: caracterización clínica y molecular de dos casos en una población altamente inmunizada
    (2018) Le Corre Pérez, Monique Nicole; Barria, S.; Lopez, T.; Martinez Valdebenito, Constanza; Contreras Sepúlveda, Ana María; Ferrés Garrido, Marcela Viviana