Examinando por Autor "Sáenz, Leonardo"

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    High prevalence of pathogenic Leptospira in alien American mink (Neovison vison) in Patagonia
    (Sociedad de Biología de Chile, 2014) Barros, Macarena; Sáenz, Leonardo; LapierreII, Lisette; Nuñez, Camila; Medina-Vogel, Gonzalo
    BACKGROUND: Leptospirosis is an important zoonosis with worldwide distribution caused by pathogenic bacteria of the genus Leptospira. The North American mink (Neovison vison) has an important role in the environmental contamination with Leptospira, as minks live in aquatic environments and are the predators of rodents. FINDINGS: Blood and kidney samples were obtained from 57 minks in Southern Chile 39° S to 45° S. Pathogenic species of Leptospira were detected by PCR on 31/57 minks. To determine the species, we sequenced the 16S ribosomal RNA (rRNA) gene on nine of the positive samples. We predicted two pathogenic species: Leptospira interrogans (five samples) and Leptospira borgpetersenii (four samples). CONCLUSIONS: This study showed that the American mink presents pathogenic species of Leptospira and confirm important environmental contamination of Patagonian rivers and lakes with pathogenic Leptospira.
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    Novel Proteoliposome-Based Vaccine against E. coli: A Potential New Tool for the Control of Bovine Mastitis
    (MDPI, 2022-09) Quiroga, John; Vidal, Sonia; Siel, Daniela; Caruffo, Mario; Valdés, Andrea; Cabrera, Gonzalo; Lapierre, Lissette; Sáenz, Leonardo
    Escherichia coli is an important causative agent of clinical mastitis in cattle. Current available vaccines have shown limited protection. We evaluated the efficacy of a novel vaccine based on bacterial proteoliposomes derived from an E. coli field strain. Female BALB/c mice were immunized subcutaneously with two doses of the vaccine, 3 weeks apart. Between days 5 and 8 after the first inoculation, the females were mated. At 5–8 days postpartum, the mice were intramammary challenged with the same E. coli strain. Two days after bacterial infection, mice were euthanized, and the mammary glands were examined and removed to evaluate the efficacy and safety of the vaccine as well as the immune response generated by the new formulation. The vaccinated mice showed mild clinical symptoms and a lower mammary bacterial load as compared to non-vaccinated animals. The vaccination induced an increase in levels of IgG, IgG1 and IgG2a against E. coli in blood and mammary glands that showed less inflammatory infiltration and tissue damage, as compared to the control group. In summary, the vaccine based on bacterial proteoliposomes is safe, immunogenic, and effective against E. coli, constituting a new potential tool for mastitis control. © 2022 by the authors.
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    Reproductive and Behavioral Evaluation of a New Immunocastration Dog Vaccine
    (MDPI AG, 2020-02) Siel, Daniela; Ubilla, María José; Vidal, Sonia; Loaiza, Alexandra; Quiroga, John; Cifuentes, Federico; Hardman, Timothy; Lapierre, Lisette; Paredes, Rodolfo; Sáenz, Leonardo
    Canine immunocastration development has been of interest for many years as a complementary strategy to surgical castration. The purpose of this paper was to verify the effect of a recombinant vaccine for dog immunocastration. Two tests were done, one under controlled conditions and a second under field conditions. Animals were injected with 1 mL of 500 µg GnRXG/Q recombinant protein; 500 µg of low molecular weight chitosan as adjuvant; 1 mL NaCl 0.9% q.s. In the first trial, eight Beagle male dogs between the ages of 1 and 3 comprised the sample, randomly divided into two groups: vaccinated group (n = 7) and control group (n = 2). The second trial had 32 dogs with owners. In the first controlled conditions trial, the vaccine produced specific antibodies that remained until the end of the trial (day 270), inducing reduced testosterone and spermiogram changes in the immunized animals. In a second trial, on the field, specific immunity was induced, which remained high up to day 150. The vaccine also reduced sexual agonistic and marking behaviors. This new vaccine proved to be safe, immunogenic, capable of reducing gonadal functionality, and had a positive effect on inducing reduced sexual, agonistic, and marking behavior of the animals. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.