Browsing by Author "Valenzuela, Pablo D. T."

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    A vaccine against the salmonid pathogen Piscirickettsia salmonis based on recombinant proteins
    (ELSEVIER SCI LTD, 2006) Wilhelm, Vivian; Miquel, Alvaro; Burzio, Luis O.; Rosemblatt, Mario; Engel, Esteban; Valenzuela, Sebastián; Parada, Gustavo; Valenzuela, Pablo D. T.
    We report here the protective effect against piscirickettsiosis elicited in fish by a mixture of recombinant proteins. A comparative genomics strategy was used on a genomic library of Piscirickettsia salmonis in order to select optimal candidates for a recombinant subunit vaccine to protect fish from rickettsial septicaemia (SRS). Based on this information, 15 P. salmonis ORFs encoding heat shock proteins, virulence factors, membrane bound and other surface exposed antigens, were isolated and expressed. Seven of the most promising antigens were formulated in three mixtures (V1-V3) containing two or three recombinant proteins each and injected into salmon to test their protective efficacy. Two of the three formulations (V1, V2) elicited a strong protective response in a challenge against the pathogen, which was coincident with the humoral response against the corresponding recombinant proteins present in each formulation. V I, formulated with recombinant chaperonines Hsp60, Hsp70 and flagellar protein FlgG of P. salmonis achieved the highest level of protection with a relative percent survival (RPS) of 95%. (c) 2006 Elsevier Ltd. All rights reserved.
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    Andes Virus Antigens Are Shed in Urine of Patients with Acute Hantavirus Cardiopulmonary Syndrome
    (AMER SOC MICROBIOLOGY, 2009) Godoy, Paula; Marsac, Delphine; Stefas, Elias; Ferrer, Pablo; Tischler, Nicole D.; Pino, Karla; Ramdohr, Pablo; Vial, Pablo; Valenzuela, Pablo D. T.; Ferres, Marcela; Veas, Francisco; Lopez Lastra, Marcelo
    Hantavirus cardiopulmonary syndrome (HCPS) is a highly pathogenic emerging disease (40% case fatality rate) caused by New World hantaviruses. Hantavirus infections are transmitted to humans mainly by inhalation of virus-contaminated aerosol particles of rodent excreta and secretions. At present, there are no antiviral drugs or immunotherapeutic agents available for the treatment of hantaviral infection, and the survival rates for infected patients hinge largely on early virus recognition and hospital admission and aggressive pulmonary and hemodynamic support. In this study, we show that Andes virus (ANDV) interacts with human apolipoprotein H (ApoH) and that ApoH-coated magnetic beads or ApoH-coated enzyme-linked immunosorbent assay plates can be used to capture and concentrate the virus from complex biological mixtures, such as serum and urine, allowing it to be detected by both immunological and molecular approaches. In addition, we report that ANDV-antigens and infectious virus are shed in urine of HCPS patients.
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    Generation and analysis of expressed sequence tags from Botrytis cinerea
    (2006) Silva, Evelyn; Valdes, Jorge; Holmes, David; Shmaryahu, Amir; Valenzuela, Pablo D. T.
    Botrytis cinerea is a filamentous plant pathogen of a wide range of plant species. and its infection may cause enormous damage both during plant growth and in the post-harvest phase. We have constructed a cDNA library from an isolate of B. cinerea and have sequenced 11.482 expressed sequence tags that were assembled into 1,003 contigs sequences and 3.032 singletons. Approximately 81% of the unigenes showed significant similarity to genes coding for proteins with known functions: more than 50% of the sequences code for genes involved in cellular metabolism. 12% for transport of metabolites. and approximately 10% for cellular organization. Other functional categories include responses to biotic and abiotic stimuli. cell communication. cell homeostasis, and cell development. We carried Out pair-wise comparisons with fungal databases to determine the B. cinerea unisequence set with relevant similarity to genes in other fungal pathogenic counterparts. Among the 4,035 non-redundant B. cinerea unigenes, 1,338 (23%) have significant homology with Fusarium verticillioides unigenes. Similar values were obtained for Saccharomyces cerevisiae and Aspergillus nidulans (22% and 24%, respectively). The lower percentages of homology were with Magnaporthe grisae and Neurospora crassa (13% and 19%. respectively). Several genes involved in putative and known fungal virulence and general pathogenicity were identified. The results provide important information for future research on this fungal pathogen.
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    Genome analysis and detection of a Chilean isolate of Grapevine leafroll associated virus-3
    (2008) Engel, Esteban A.; Girardi, Cristobal; Escobar, Paula F.; Arredondo, Vania; Dominguez, Calixto; Perez-Acle, Tomas; Valenzuela, Pablo D. T.
    The complete genome of the Chilean isolate Cl-766 of Grapevine leafroll-associated virus-3 (GLRaV-3) has been sequenced. This is the first genome sequence obtained from a GLRaV-3 isolate of the Southern hemisphere. The genomic RNA of 17,919 nucleotides contains 13 open reading frames (ORFs) with 5' and 3' untranslated regions (UTR) of 158 and 277 nucleotides, respectively. Comparison with NY1, the only isolate with complete genomic sequence available today, shows 97.6% nucleotide identity between the two isolates. Examination of the genome variability shows that most of the genetic diversity is concentrated in ORF1a. Three additional isolates from different geographic regions of Chile were partially sequenced as well, one which showed sequence divergence with respect to the other local and foreign isolates, indicative of different evolutionary constrains. Immunodetection systems were developed using monoclonal and polyclonal antibodies produced against the recombinant major coat protein of GLRaV-3, providing sensitive and specific detection using a triple antibody sandwich-enzyme linked immunosorbent assay (TAS-ELISA) and an immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) assay.