Faculty Research Publications (College of Veterinary Medicine)

Development of monoclonal antibody-based assays for the detection of Vibrio tubiashii zinc-metalloprotease (VtpA)

Thu, 09 May 2013 00:00:00 GMT

Development of monoclonal antibody-based assays for the detection of Vibrio tubiashii zinc-metalloprotease (VtpA) Dima N. Gharaibeh; Frances M. Biel; Claudia C. Häse Vibrio tubiashii has been linked to disease outbreaks in molluscan species, including oysters, geoducks, and clams. In particular, oyster hatcheries in the Pacific Northwest have been plagued by intermittent vibriosis since 2006. Accurate detection of vibrios, including V. tubiashii, is critical to the hatcheries in order to allow for rapid remediation efforts. The current methods for detection of Vibrio spp. are not ideal for use at the hatchery. Plating samples requires time and is not sensitive to extracelluar pathogenic products, such as the secreted zinc-metalloprotease, VtpA. Other sensitive methods to detect bacteria, such as qPCR, require a high level of laboratory skills and expensive supplies that are prohibitive for use at hatchery sites. Thus, hatcheries would benefit from a sensitive, simple method to detect V. tubiashii and its secreted toxin. Here, we describe the development of two inexpensive and highly specific tests for the shellfish-toxic zinc-metalloprotease secreted by V. tubiashii: enzyme-linked immunoassays (ELISA) and a lateral flow immunoassay (dipstick assay). Both technologies rely on a set of monoclonal antibodies used in a sandwich format, with the capture antibody recognizing a different epitope than the detection antibody on the mature VtpA protein. Both assays are quantitative and give colorimetric readouts. The sandwich ELISA was sensitive when VtpA was diluted into PBS, but was markedly less sensitive in conditions that correlate with the environment of hatchery-derived samples, such as in the presence of seawater, algae, or oyster larvae. In contrast, the dipstick assay remained very sensitive in the presence of these contaminants, is less work-intensive, and much more rapid, making this format the preferred assay method for detecting VtpA on site in a hatchery or environmental setting. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

A review of episodes of zinc phosphide toxicosis in wild geese (Branta spp.) in Oregon (2004–2011)

Fri, 04 Jan 2013 00:00:00 GMT

A review of episodes of zinc phosphide toxicosis in wild geese (Branta spp.) in Oregon (2004–2011) Bildfell, Rob J.; Rumbeiha, Wilson K.; Schuler, Krysten L.; Meteyer, Carol U.; Wolff, Peregrine L.; Gillin, Colin M. Epizootic mortality in several geese species, including cackling geese (Branta hutchinsii) and Canada geese (Branta canadensis), has been recognized in the Willamette Valley of Oregon for over a decade. Birds are generally found dead on a body of water or are occasionally observed displaying neurologic clinical signs such as an inability to raise or control the head prior to death. Investigation of these epizootic mortality events has revealed the etiology to be accidental poisoning with the rodenticide zinc phosphide (Zn₃ P₂ ). Gross and histologic changes are restricted to acute pulmonary congestion and edema, sometimes accompanied by distension of the upper alimentary tract by fresh grass. Geese are unusually susceptible to this pesticide; when combined with an epidemiologic confluence of depredation of specific agricultural crops by rodents and seasonal avian migration pathways, epizootic toxicosis may occur. Diagnosis requires a high index of suspicion, appropriate sample collection and handling, plus specific test calibration for this toxicant. Interagency cooperation, education of farmers regarding pesticide use, and enforcement of regulations has been successful in greatly decreasing these mortality events since 2009. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Sage and can be found at: http://www.sagepub.com/home.nav.

Effect of Feeding Selenium-Fertilized Alfalfa Hay on Performance of Weaned Beef Calves

Mon, 11 Mar 2013 00:00:00 GMT

Effect of Feeding Selenium-Fertilized Alfalfa Hay on Performance of Weaned Beef Calves Hall, Jean A.; Bobe, Gerd; Hunter, Janice K.; Vorachek, William R.; Stewart, Whitney C.; Vanegas, Jorge A.; Estill, Charles T.; Mosher, Wayne D.; Pirelli, Gene J. Selenium (Se) is an essential micronutrient in cattle, and Se-deficiency can affect morbidity and mortality. Calves may have greater Se requirements during periods of stress, such as during the transitional period between weaning and movement to a feedlot. Previously, we showed that feeding Se-fertilized forage increases whole-blood (WB) Se concentrations in mature beef cows. Our current objective was to test whether feeding Se-fertilized forage increases WB-Se concentrations and performance in weaned beef calves. Recently weaned beef calves (n = 60) were blocked by body weight, randomly assigned to 4 groups, and fed an alfalfa hay based diet for 7 wk, which was harvested from fields fertilized with sodium-selenate at a rate of 0, 22.5, 45.0, or 89.9 g Se/ha. Blood samples were collected weekly and analyzed for WB-Se concentrations. Body weight and health status of calves were monitored during the 7-wk feeding trial. Increasing application rates of Se fertilizer resulted in increased alfalfa hay Se content for that cutting of alfalfa (0.07, 0.95, 1.55, 3.26 mg Se/kg dry matter for Se application rates of 0, 22.5, 45.0, or 89.9 g Se/ha, respectively). Feeding Se-fertilized alfalfa hay during the 7-wk preconditioning period increased WB-Se concentrations (P[subscript Linear] < 0.001) and body weights (P[subscript Linear] = 0.002) depending upon the Se-application rate. Based upon our results we suggest that soil-Se fertilization is a potential management tool to improve Se-status and performance in weaned calves in areas with low soil-Se concentrations. This is the publisher’s final pdf. The published article is copyrighted by Public Library of Science and can be found at: http://www.plos.org/.

Infecciones causadas por Clostridium diffi cile: una visión actualizada

Wed, 01 Aug 2012 00:00:00 GMT

Infecciones causadas por Clostridium diffi cile: una visión actualizada Hernandez-Rocha, Cristian; Naour, Sebastian; Alvarez-Lobos, Manuel; Paredes-Sabja, Daniel English: Clostridium difficile is an emerging anaerobic, spore forming pathogen, recognized as the etiological agent of ~ 30% of antibiotic associated diarrheas. Clinical symptoms can fluctuate from mild to moderate diarrhea, pseudomembranous colitis and toxic megacolon. The incidence of C. difficile associated infections (CDAI) is ~ 1% of total hospitalized patients. CDAI has a mortality rate of ~1 to 5%, and a relapse rate of ~ 20%. The appearance of severe outbreaks of CDAI could be attributed to changes in the production of the two major virulence factors, the enterotoxins TcdA and TcdB, which produce massive epithelial damage. C. difficile spores play an essential role in transmission, initiation and persistence of CDAI. Recent advances in detection methods, development of novel therapies and prevention methods could allow a reduction on the frequency of CDAI. The objective of this review is to provide an updated view on the mechanisms of pathogenesis, epidemiology, risk factors, detection methods, treatment and prevention of CDAI. Spanish: Clostridium difficile es un patógeno emergente, anaerobio estricto, capaz de formar esporas, y reconocido como el agente etiológico de ~30% de las diarreas asociadas al uso de antimicrobianos. Los síntomas clínicos varían desde una diarrea leve a una colitis pseudomembranosa o megacolon tóxico. La incidencia de las infecciones asociadas a C. difficile (IACD) es de ~1% del total de pacientes hospitalizados y su tasa de mortalidad es de ~1,a 5%, con una elevada tasa de recurrencia de ~20%. Cambios en los principales factores de virulencia como es la producción de dos enterotoxinas, TcdA y TcdB, que provocan daño epitelial, pueden explicar recientes brotes graves de IACD. Las esporas de C. difficile juegan un rol esencial en la transmisión, iniciación y persistencia de las IACD. Novedosos avances en métodos diagnósticos, desarrollo de nuevas terapias y métodos de prevención podrían reducir las tasas de incidencia y su gravedad. El objetivo de esta revisión es entregar una actualización sobre los mecanismos de patogénesis, epidemiología, factores de riesgo, métodos de detección, tratamientos y prevención de las IACD. This is the publisher’s final pdf. The published article is copyrighted by Sociedad Chilena de Infectología and can be found at: http://www.scielo.cl/scielo.php?script=sci_serial&pid=0716-1018&lng=en&nrm=iso.