Susan Williams | The University of Georgia (original) (raw)

Papers by Susan Williams

Avian Pathology, Jul 14, 2008

Reticuloendotheliosis virus (REV) infection can result in immunosuppression, runting syndrome, hi... more Reticuloendotheliosis virus (REV) infection can result in immunosuppression, runting syndrome, high mortality, acute reticular cell neoplasia, or T-and/or B-cell lymphoma, in a variety of domestic and wild birds. Histopathological changes of reticuloendotheliosis (RE) are not sufficient to differentiate it from Avian Leukosis (AL) and Marek's disease (MD). Currently there are no available diagnostic methods for detection of active REV infection. In order to develop immunohistochemistry (IHC) and in situ hybridization (ISH) assays for detection of REV active infections, experimentally inoculated formalin-fixed and paraffin embedded DF-1 chicken embryo fibroblasts were used as an infection model. IHC and ISH assays proved to be efficient for the detection of several REV strains, and to differentiate those strains from representative strains of the avian leukosis/sarcoma group of retroviruses (ALSV).

Journal of Avian Medicine and Surgery, Jun 1, 2012

Increased activities of certain biochemical enzymes (alanine aminotransferase [ALT], aspartate am... more Increased activities of certain biochemical enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], lactate dehydrogenase [LDH], alkaline phosphatase [ALP]) have been associated with blunt liver injury in many species. To evaluate changes in plasma hepatic biochemical parameters in acute avian liver disease caused by trauma and to compare biochemical changes with histologic lesions in hepatic parenchyma, 30 healthy fasted Indian ring-necked parakeets (Psittacula krameri manillensis) were divided into 2 groups, and traumatic liver injury was caused by endoscopic liver biopsy (group 1) or by liver biopsy and crushing injury to the hepatic parenchyma with endoscopic forceps (group 2) in anesthetized birds. Blood samples were collected at baseline and at 12, 24, 36, 48, 60, 72, 84, 96, 108, and 120 hours in alternate groups to compare analyte values after injury with those at baseline. Results showed consistently decreased plasma ALP activity (excluding 1 time point) throughout the study, which was thought to be associated with isoflurane administration. Plasma glutamate dehydrogenase activity initially increased but rapidly declined thereafter and was attributed to acute focal hepatocellular injury. In both groups, increases in plasma AST, ALT, and LDH activities was most likely caused by muscle injury because creatine kinase activity was concurrently increased. Compared with baseline values, bile acid concentration and y-glutamyl transferase activity were not affected by liver biopsy or crush injury. Plasma sorbitol dehydrogenase activity was the most specific indicator of liver injury in both groups. Histologic changes correlated poorly with biochemical results, possibly because the small area of hepatic parenchyma that was damaged did not affect enzyme values substantially.

Poultry Science, Jul 1, 2018

A study was conducted to evaluate the efficacy of fructooligosaccharides (FOS) in controlling the... more A study was conducted to evaluate the efficacy of fructooligosaccharides (FOS) in controlling the infection of Salmonella Enteritidis (SE) in White Leghorns. A total of 30 laying hens (white leghorns W-36) were challenged both orally and cloacally with approximately 108 colony-forming units of nalidxic acid resistant SE (SENAR) and divided into 3 treatments: 1) SENAR challenged + 0.0% FOS, 2) SENAR challenged + 0.5% FOS (Nutraflora), and 3) SENAR challenged + 1.0% FOS. SENAR recovery via fecal shedding was measured at 3- and 6-d post-infection (dpi), whereas in the ceca and internal organs, SENAR recovery was measured at 7-d post-infection. In the first experiment, there was a 1.0 log10 and a 1.3 log10 reduction in cecal SENAR by supplementation of FOS at 0.5 and 1.0%, respectively. In the second experiment, there was a 0.6 log10 and a 0.8 log10 reduction in cecal SENAR by supplementation of FOS at 0.5 and 1.0%, respectively. Fecal shedding was significantly lower in 1.0% FOS supplemented groups compared to SENAR challenge 0.0% FOS. There was no significant difference among the 3 treatments on SENAR recovery in liver with gall bladder and ovaries. However, the frequency of positive SENAR in the ovaries (10 to 40%) in SENAR challenge 0.0% FOS was significantly lower than liver with gall bladder (60 to 80%) in both experiments. There was a significant upregulation of toll-like receptor-4 in 1.0% FOS and interferon gamma in both 0.5 and 1.0% FOS. Histologic measurements of ileal villi height and crypt depth were similar across all treatments. Immunohistochemistry analyses of ileal samples showed that immunoglobulin A positive cells increased as FOS concentration increased reaching significance at 1.0% as well as altered cytokine gene expression in the ileum. Further, FOS supplementation also reduced cecal SENAR and feces SENAR levels. Collectively, the results suggest that dietary supplementation with FOS may impair SE pathogenesis while modulating humoral immunity within the gut-associated lymphoid tissue.

Avian Diseases, Dec 1, 2010

(Athens, GA) for diagnosis. Samples were from fancy breed chickens with a history of increased tu... more (Athens, GA) for diagnosis. Samples were from fancy breed chickens with a history of increased tumor prevalence in both hens and roosters. Microscopically, in all the samples, there were neoplastic proliferations of spindle-shaped cells. The matrix surrounding tumor cells stained positively with Alcian blue at pH 2.5, but neoplastic cells did not stain with periodic acid-Schiff. Immunohistochemistry stains were positive for vimentin and neuron-specific enolase and negative for desmin, smooth muscle actin, and S-100 protein. Tumors were determined to be myxosarcomas. All samples were positive for PCR targeting the gp85 avian leukosis virus (ALV) envelope protein. However, analysis of the predicted amino acid sequences in the envelope gene from three separate samples showed high similarity between them and to ALV subgroup A. RESUMEN. Reporte de Caso-Mixosarcomas asociados con el virus de la leucosis aviar subgrupo A en pollos de raza de ornato. Se enviaron tumores sospechosos fijados en formalina al Centro de Diagnóstico e Investigación en Avicultura en la Universidad de Georgia (Athens, Georgia) para su diagnóstico. Las muestras provenían de pollos de ornato con una historia de prevalencia de tumores en gallinas y gallos. Microscópicamente, en todas las muestras se observó proliferación neoplásica con células fusiformes. La matriz que rodea a las células tumorales se tiñó de manera positiva con la tinción de azul alcián con un pH de 2.5, pero las células neoplásicas no se tiñeron con ácido peryódico de Schiff. Las tinciones de inmunohistoquímica fueron positivas para la vimentina y la enolasa específica de neuronas y fueron negativas para la desmina, para la actina de músculo liso y para la proteína S-100. Se determinó que los tumores eran mixosarcomas. Todas las muestras fueron positivas para la reacción en cadena de la polimerasa (PCR) dirigida a la proteína de la envoltura gp85 del virus de la leucosis aviar. Sin embargo, el análisis de las secuencias predichas de aminoácidos del gen de la envoltura de tres muestras separadas, mostraron alta similitud entre ellos y con el virus de la leucosis aviar subgrupo A.

Avian Diseases, Sep 1, 2007

Three 7-wk-old Bobwhite quail were submitted for necropsy to the Douglas branch of the Georgia Po... more Three 7-wk-old Bobwhite quail were submitted for necropsy to the Douglas branch of the Georgia Poultry Laboratory Network. Grossly, one bird had multiple white foci in the liver and a mild airsacculitis. In this quail there were multiple hepatic granulomas that contained mats of filamentous bacteria easily seen in hematoxylin-and eosin-stained histologic sections. These bacteria were negative with period acid-Schiff and were not acid fast. Bacteria were gram-positive but were most evident on Warthin-Starry silver-stained sections. The appearance and histochemical characteristics of these bacteria are most consistent with Eubacterium tortuosum. RESUMEN. Reporte de Caso-Granulomas hepáticos debidos a Eubacterium tortuosum en una codorniz Virginiana de siete semanas de edad. Se recibieron para necropsia tres codornices Virginianas de siete semanas de edad en el laboratorio de Douglas, Georgia, parte de la red de laboratorios de Diagnóstico del estado de Georgia. Macroscópicamente, un ave mostraba múltiples focos blancos en el hígado y una aerosaculitis leve. En esta ave se observaron múltiples granulomas hepáticos que contenían gran cantidad de bacterias filamentosas observadas fácilmente en las secciones histológicas coloreadas con hematoxilina-eosina. Estas bacterias fueron negativas a la tinción ácido resistente de Schiff. Las bacterias eran Gram positivas pero fueron más evidentes en las secciones teñidas con la coloración de plata Warten-Starry. La apariencia y las características histoquímicas de estas bacterias son concomitantes con Eubacterium tortuosum.

Avian Diseases, Mar 1, 2007

A 15-cm segment of small intestine from a 7-wk-old broiler chicken presented for slaughter was en... more A 15-cm segment of small intestine from a 7-wk-old broiler chicken presented for slaughter was encased by a firm, white mass. Other tissues were grossly unremarkable. Microscopically, the enteric serosa and peripheral muscularis of this segment of small intestine were replaced by a fibrosarcoma. Numerous linear, intracytoplasmic, eosinophilic inclusion bodies were present in smooth muscle cells of the muscularis of the small intestine, and a few similar inclusions were present in the muscularis of the proventriculus. In the heart, there were rare intracytoplasmic inclusions typical of viral matrix inclusions. Ultrastructurally, inclusion bodies in enteric smooth muscle were viral matrix inclusions, and virions resembling avian retroviruses were present in adjacent intercellular spaces. Polymerase chain reaction (PCR) of the deoxyribonucleic acid (DNA) extracted from tumor tissues indicated the presence of proviral DNA of subgroup J avian leukosis virus. This is the first description of the light microscopic appearance of these viral matrix inclusions in enteric smooth muscle. RESUMEN. Reporte de Caso-Inclusiones retrovirales en el músculo liso entérico de un pollo joven con un tumor. Un segmento de 15 centímetros de intestino delgado proveniente de un pollo de engorde de 7 semanas de edad estaba envuelto por una masa blanca firme al momento del sacrificio. Los otros tejidos estaban macroscópicamente libres de lesiones. Microscópicamente, la serosa entérica y la capa muscular periférica de este segmento del intestino delgado habían sido sustituidas por un fibrosarcoma. Numerosos cuerpos de inclusión intracitoplasmáticos lineares estaban presentes en las células del músculo liso de la capa muscular del intestino delgado, algunas inclusiones similares estaban presentes en la capa muscular del proventrículo. En el corazón, se observaron inclusiones intracitoplasmáticas escasas, típicas de las inclusiones virales de la proteína matriz. Ultraestructuralmente, los cuerpos de inclusión en el músculo liso entérico eran inclusiones virales de la proteína matriz, mientras que se observaron viriones parecidos a retrovirus aviares en los espacios intracelulares adyacentes. La prueba de reacción en cadena por la polimerasa del ADN extraído de los tejidos tumorales indicó la presencia de ADN proviral del subgrupo J del virus de leucosis aviar. Esta es el primer reporte de la observación al microscopio de luz de inclusiones virales de la proteína de la matriz en el músculo liso entérico.

Avian Diseases, Dec 1, 2009

The pathogenesis, virus shedding, and serologic response in specific-pathogen-free (SPF) chickens... more The pathogenesis, virus shedding, and serologic response in specific-pathogen-free (SPF) chickens and commercial turkeys against H4, H6, and H9 type low pathogenic avian influenza viruses (LPAI) from wild birds was examined. Four-week-old chickens and three-week-old turkeys were given 1 3 10 6 EID 50 of LPAI per bird, intrachoanally, and examined for clinical signs for 3 wk. Oropharyngeal and cloacal swabs, and fecal samples, were collected at 2, 4, and 7 days postinoculation (PI) for virus detection by real-time RT-PCR. Serum was collected at 7, 14, and 21 days PI and examined for antibodies against avian influenza virus (AIV) by the enzyme-linked immunosorbant assay (ELISA) and hemagglutination inhibition tests. Tissue samples for histopathology were collected from three birds per group at 3 days PI. The hemagglutinin genes of the viruses were sequenced, and phylogenetic analysis was conducted. Clinical signs ranged from no clinical signs to moderate depression, decreased activity, and decreased food and water consumption. Based on virus detection results, SPF chickens were generally found to be shedding more virus from both the oropharynx and cloaca than were commercial turkeys. Microscopic lesion results in both species showed the predominance of lesions in the respiratory and gastrointestinal tract, which is consistent with the fact that these viruses are of low pathogenicity. In chickens and turkeys, oropharyngeal shedding strongly correlated with the lesions found in the upper respiratory tract. Turkeys had fewer lesions in the respiratory tract and more lesions in the gastrointestinal tract compared to chickens. Thirteen LPAI viruses caused seroconversion in commercial turkeys, whereas only 6 LPAI viruses caused seroconversion in SPF chickens. Phylogenetic analysis of the HA genes showed that the H4, H6, and H9 viruses evaluated here represented the full genetic diversity of North American AIVs of their respective subtypes. This data is important for surveillance and control because some of the LPAI viruses (of wild bird origin and examined in this study) that can infect and be shed by chickens and turkeys would be difficult to detect in commercial poultry. Specifically, detection is difficult because these viruses did not cause overt clinical disease or mortality, but only induced mild microscopic lesions and exhibited poor seroconversion.

Avian Diseases Digest, Dec 1, 2008

Avian Diseases, Jun 1, 2008

The development and use of recombinant vaccine vectors for the expression of poultry pathogens pr... more The development and use of recombinant vaccine vectors for the expression of poultry pathogens proteins is an active research field. The adeno-associated virus (AAV) is a replication-defective virus member of the family Parvoviridae that has been successfully used for gene delivery in humans and other species. In this experiment, an avian adeno-associated virus (AAAV) expressing the infectious bursal disease virus (IBDV) VP2 protein (rAAAV-VP2) was evaluated for protection against IBDVvirulent challenge. Specific pathogen free (SPF) birds were inoculated with rAAAV-VP2 or with a commercial intermediate IBDV vaccine and then challenged with the Edgar strain. IBDV-specific antibody levels were observed in all vaccinated groups; titers were higher for the commercial vaccine group. The live, commercial vaccine induced adequate protection against morbidity and mortality; nevertheless, initial lymphoid depletion and follicular atrophy related to active viral replication was observed as early as day 14 and persisted up to day 28, when birds were challenged. No bursal tissue damage due to rAAAV-VP2 vaccination was observed. Eight-out-often rAAAV-VP2-vaccinated birds survived the challenge and showed no clinical signs. The bursa:body weight ratio and bursa lesion scores in the rAAAV-VP2 group indicated protection against challenge. Therefore, transgenic expression of the VP2 protein after rAAAV-VP2 vaccination induced protective immunity against IBDV challenge in 80% of the birds, without compromising the bursa of Fabricius. The use of rAAAV virions for gene delivery represents a novel approach to poultry vaccination. RESUMEN. Nota de Investigación-Protección contra un desafío virulento del virus de la enfermedad infecciosa de la bolsa conferida por una vacuna recombinante del virus adeno-asociado aviar. El desarrollo y uso de vectores vacunales recombinantes para la expresión de proteínas de patógenos aviares es un área activa de investigación. El virus adeno-asociado aviar es un virus de replicación defectiva, miembro de la familia Parvoviridae que ha sido utilizado exitosamente para la transferencia de genes en humanos y otras especies. En este experimento, se evaluó la protección contra un desafío virulento del virus de la enfermedad infecciosa de la bolsa conferida por un virus adeno-asociado aviar expresando la proteína viral 2 (VP2) del virus de la enfermedad infecciosa de la bolsa (por sus siglas en Inglés rAAAV-VP2). Se inocularon aves libres de patógenos específicos con la recombinante rAAAV-VP2 o con una vacuna comercial intermedia del virus de la enfermedad infecciosa de la bolsa y luego fueron desafiados con la cepa Edgar. En todos los grupos vacunados se observaron anticuerpos específicos contra el virus de la enfermedad infecciosa de la bolsa. Los títulos de anticuerpos fueron mayores en el grupo vacunado con la vacuna comercial. La vacuna comercial a virus vivo indujo una protección adecuada contra morbilidad y mortalidad, sin embargo, tan temprano como el día 14 y hasta el día 28 cuando se desafiaron las aves, se observó depresión linfoide y atrofia folicular inicial asociada con la replicación viral activa. No se observó daño en el tejido de la bolsa debido a la vacuna recombinante rAAAV-VP2. Ocho de diez aves vacunadas con la recombinante sobrevivieron al desafío y no mostraron signos clínicos. El índice de peso bolsa:peso corporal y el registro de lesiones de la bolsa en el grupo vacunado con la recombinante rAAAV-VP2 indicaron protección. En consecuencia, la expresión transgénica de la proteína VP2 generó inmunidad protectora contra el desafío experimental en 80% de las aves, sin comprometer la bolsa de Fabricio. La utilización de viriones recombinantes del virus adenoasociado aviar para transferencia genética es un nuevo enfoque para la vacunación en avicultura. Key words: avian adeno-associated virus, vaccination, protection, infectious bursa disease Abbreviations: AAV 5 adeno-associated virus; AAAV 5 avian adeno-associated virus; ELISA 5 enzyme-linked immunosorbent assay; HEK 5 human embryo kidney (cells); IBDV 5 infectious bursal disease virus; IgG 5 immunoglobulin G; IM 5 intramuscular; ORF 5 open reading frames; SNK 5 Student-Newman, Keuls test; rAAAV-VP2 5 recombinant avian adeno-associated virus expressing the VP2 protein of IBDV; SPF 5 specific pathogen free

Avian Pathology, Jun 1, 2010

In the present study we describe the rapid development of an attenuated live vaccine for GA08, a ... more In the present study we describe the rapid development of an attenuated live vaccine for GA08, a new serotype of infectious bronchitis virus, using a heat-treatment method. Incubation of the GA08 strain of IBV at 56 degrees C and passage in embryonated eggs was used as a method to fast track the attenuation process. The virus was incubated in a 56 degrees C water bath and aliquots were removed every 5 min for up to 1 h, and then each aliquot was inoculated into 10-day-old embryonated eggs. Virus with the longest incubation time that produced lesions in the embryos was harvested, again incubated at 56 degrees C as described and passaged in embryonated eggs. Attenuation of the virus, designated GA08/GA08HSp16/08, was verified in 1-day-old specific pathogen free chicks. A 10x dose of the vaccine was found to be safe for 2-week-old broiler chicks of commercial origin. The efficacy of the heat-treated attenuated virus was determined by vaccinating broiler chicks of commercial origin at 1 and 14 days of age intraocularly/intranasally. Vaccinated birds that were challenged with 10(4.5) median embryo infectious doses of pathogenic GA08 virus/bird at 28 days of age were protected from the disease, and challenge virus was only detected in the trachea of one of 21 birds by real-time reverse transcriptase-polymerase chain reaction at 5 days post challenge. The attenuation process took 10 weeks to complete, which is a substantially shorter time than required to attenuate infectious bronchitis virus by serial passage in embryonated eggs without heat treatment (38 weeks or more).

Journal of Veterinary Diagnostic Investigation, 2007

Formalin fixed paraffin embedded tissues blocks are used routinely to diagnose the economically i... more Formalin fixed paraffin embedded tissues blocks are used routinely to diagnose the economically important immunosuppressive infectious bursal disease virus (IBDV) in chickens. Immunohistochemical detection of viruses in tissue blocks has been done with varying results between laboratories. Extraction of IBDV RNA from tissue blocks allows IBDV strain identification at a molecular level. This allows correlation between virus identity and histological lesions present in the tissue. Experimentally reverse transcription-polymerase chain reaction (RT-PCR) detectable IBDV RNA could always be extracted from tissue blocks with acute +3 or higher histological lesion scores. However, many blocks from diagnostic field cases did not yield detectable IBDV RNA, in spite of having severe IBDV histological lesion scores. The reason for this can be the effect different formalin fixation conditions have on RNA detection from tissue blocks. To study the effect of various fixation parameters on RNA extraction and immunohistochemical detection of IBDV, bursas with maximum histological lesion score of 4 for IBDV were fixed in formalin under various conditions (different pH levels, temperatures, concentrations of formalin, and fixation duration). Only tissues fixed in formalin with a pH of 7.0, concentration of 5 or 10% formaldehyde, storage temperature of 25uC or less, and kept for up to 2 weeks in formalin yielded detectable IBDV RNA upon extraction. No RNA could be detected from tissues fixed under extreme temperature, pH, or formalin concentrations. Optimal fixation conditions for IHC detection of IBDV were 10% formalin concentration, pH 7.0, and temperature of 4uC, where maximum intensity of immunostaining was observed.

Viruses, Feb 2, 2019

Avian respiratory disease causes significant economic losses in commercial poultry. Because of th... more Avian respiratory disease causes significant economic losses in commercial poultry. Because of the need to protect long-lived poultry against respiratory tract pathogens from an early age, vaccination programs for pullets typically involve serial administration of a variety of vaccines, including infectious bronchitis virus (IBV), Newcastle disease virus (NDV), and infectious laryngotracheitis virus (ILTV). Often the interval between vaccinations is only a matter of weeks, yet it is unknown whether the development of immunity and protection against challenge when vaccines are given in short succession occurs in these birds, something known as viral interference. Our objective was to determine whether serially administered, live attenuated vaccines against IBV, NDV, and ILTV influence the development and longevity of immunity and protection against challenge in long-lived birds. Based on a typical pullet vaccination program, specific-pathogen-free white leghorns were administered multiple live attenuated vaccines against IBV, NDV, and ILTV until 16 weeks of age (WOA), after which certain groups were challenged with IBV, NDV, or ILTV at 20, 24, 28, 32, and 36 WOA. Five days post-challenge, viral load, clinical signs, ciliostasis, tracheal histopathology, and antibody titers in serum and tears were evaluated. We demonstrate that pullets serially administered live attenuated vaccines against IBV, NDV, and ILTV were protected against homologous challenge with IBV, NDV, or ILTV for at least 36 weeks, and conclude that the interval between vaccinations used in this study (at least 2 weeks) did not interfere with protection. This information is important because it shows that a typical pullet vaccination program consisting of serially administered live attenuated vaccines against multiple respiratory pathogens can result in the development of protective immunity against each disease agent.

Avian Diseases, Jun 1, 2007

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Virus Research, Apr 1, 2010

Anti-coronaviral activity of a mixture of oleoresins and essential oils from botanicals, designat... more Anti-coronaviral activity of a mixture of oleoresins and essential oils from botanicals, designated QR448(a), was examined in vitro and in vivo. Treatment of avian infectious bronchitis virus (IBV) with QR448(a) reduced the virus titer as measured in two laboratory host systems, Vero E6 cells and embryonating eggs. The effect of QR448(a) on IBV in chickens was also investigated. Administering QR448(a) to chickens at a 1:20 dilution by spray, 2 h before challenge with IBV was determined to be the most effective treatment. Treatment decreased the severity of clinical signs and lesions in the birds, and lowered the amount of viral RNA in the trachea. Treatment with QR448(a) protected chickens for up to 4 days posttreatment from clinical signs of disease (but not from infection) and decreased transmission of IBV over a 14-day period. Anti-IBV activity of QR448(a) was greater prior to virus attachment and entry indicating that the effect is virucidal. In addition, QR448(a) had activity against both Massachusetts and Arkansas type IB viruses, indicating that it can be expected to be effective against IBV regardless of serotype. To our knowledge, this is the first report on the in vivo use of a virucidal mixture of compounds effective against the coronavirus IBV.

Virology, Mar 1, 2010

Real-time reverse transcriptase polymerase chain reaction Comparative genomics Sequencing Analyse... more Real-time reverse transcriptase polymerase chain reaction Comparative genomics Sequencing Analyses of turkey coronavirus (TCoV), an enteric disease virus that is highly similar to infectious bronchitis virus (IBV) an upper-respiratory tract disease virus in chickens, were conducted to determine the adaptive potential, and genetic changes associated with emergence of this group 3 coronavirus. Strains of TCoV that were pathogenic in poults and nonpathogenic in chickens did not adapt to cause disease in chickens. Comparative genomics revealed two recombination sites that replaced the spike gene in IBV with an unidentified sequence likely from another coronavirus, resulting in cross-species transmission and a pathogenicity shift. Following emergence in turkeys, TCoV diverged to different serotypes through the accumulation of mutations within spike. This is the first evidence that recombination can directly lead to the emergence of new coronaviruses and new coronaviral diseases, emphasizing the importance of limiting exposure to reservoirs of coronaviruses that can serve as a source of genetic material for emerging viruses.

Virus Genes, 2011

Full-length genome sequencing of pathogenic and attenuated (for chickens) avian coronavirus infec... more Full-length genome sequencing of pathogenic and attenuated (for chickens) avian coronavirus infectious bronchitis virus (IBV) strains of the same serotype was conducted to identify genetic differences between the pathotypes. Analysis of the consensus full-length genome for three different IBV serotypes (Ark, GA98, and Mass41) showed that passage in embryonated eggs, to attenuate the viruses for chickens, resulted in 34.75-43.66% of all the amino acid changes occurring in nsp 3 within a virus type, whereas changes in the spike glycoprotein, thought to be the most variable protein in IBV, ranged from 5.8 to 13.4% of all changes. The attenuated viruses did not cause any clinical signs of disease and had lower replication rates than the pathogenic viruses of the same serotype in chickens. However, both attenuated and pathogenic viruses of the same serotype replicated similarly in embryonated eggs, suggesting that mutations in nsp 3, which is involved in replication of the virus, might play an important role in the reduced replication observed in chickens leading to the attenuated phenotype.

Avian Diseases, Dec 1, 2008

Pathogens of free-ranging chickens create a risk of disease for wild birds, some of which migrate... more Pathogens of free-ranging chickens create a risk of disease for wild birds, some of which migrate to the United States, as well as potential economic losses for resource-poor farmers. Free-roaming backyard chickens are commonly kept in shadegrown coffee plantations, habitats that attract large numbers of wild birds. The husbandry and pathogen prevalence of backyard chicken flocks in San Luis, Costa Rica, were investigated. Based on serologic evidence, Newcastle disease virus, infectious laryngotracheitis virus, infectious bronchitis virus, chicken anemia virus, and infectious bursal disease virus, as well as both Mycoplasma gallisepticum and Mycoplasma synoviae, appear to be significant diseases of this population, and thus, we consider these backyard chickens potential reservoirs for these diseases. There was no evidence of avian influenza. Interviews, clinical examinations, and microscopic examination of tissues led us to believe that poxvirus is also a significant cause of morbidity and mortality in these chickens. We found that Escherichia coli isolates were resistant against tilmicosin, tetracycline, ampicillin, amoxicillin with clavulanic acid, ticarcillin, and cephalothin, and contained genes considered responsible for conferring tetracycline resistance. Additionally, although production was not measured, we suspect that husbandry and lack of preventative medicine are directly related to the diseases reported, all of which negatively affect production. RESUMEN. Las parvadas de aves de traspatio representan un riesgo de enfermedad para las aves tropicales en Costa Rica. Los patógenos de las aves de traspatio generan un riesgo de enfermedad para las aves silvestres, algunas de las cuales migran a los Estados Unidos, generando a su vez potenciales pérdidas económicas para granjeros de escasos recursos. Las aves de traspatio criadas a la intemperie son comúnmente mantenidas en plantaciones de café con abundante sombra, un habitat que atrae un gran número de aves silvestres. En San Luis, Costa Rica, se investigó el manejo y la prevalencia de patógenos en aves de traspatio. Basado en evidencia serológica, los virus de la enfermedad de Newcastle, laringotraqueitis infecciosa, bronquitis infecciosa, anemia infecciosa aviar y enfermedad infecciosa de la bolsa, así como el Mycoplasma gallisepticum y el Mycoplasma synoviae, son agentes causantes de enfermedades en esta población y en consecuencia se consideran a estas aves de traspatio como reservorios potenciales de estas enfermedades. No se encontró evidencia de influenza aviar. Entrevistas, exámenes clínicos y evaluaciones microscópicas de tejidos nos llevan a creer que el virus de la viruela aviar es también una causa significativa de morbilidad y mortalidad en estas aves. Se demostró que los aislamientos de Escherichia coli eran resistentes a la tilmicosina, tetraciclina, ampicilina, amoxiciclina y ácido clavulánico, ticarciclina, cefalocina y contenían genes considerados responsables de conferir la resistencia a la tetraciciclina. Adicionalmente, aunque no se midió la producción, se sospecha que las prácticas de manejo y la falta de medicina preventiva están directamente relacionadas con las enfermedades reportadas, todas capaces de afectar negativamente la producción. Key words: husbandry, free-ranging, backyard chickens, wild birds, pathogens, antimicrobial resistance, Costa Rica Abbreviations: AE 5 avian encephalomyelitis virus; AI 5 avian influenza; AMRP 5 antimicrobial resistance profile; APV 5 avian pneumovirus; CAV 5 chicken anemia virus; ELISA 5 enzyme-linked immunosorbent assay; IBD 5 infectious bursal disease; IBV 5 avian infectious bronchitis; ILT 5 infectious laryngotracheitis; MAG 5 Costa Rican Ministry of Agriculture; MIC 5 minimum inhibitory concentrations; MG 5 Mycoplasma gallisepticum; MS 5 Mycoplasma synoviae; NDV 5 Newcastle disease virus; PDRC 5 Population Diagnostic Research Center; PPMV 5 pigeon paramyxovirus; RT-PCR 5 real-time polymerase chain reaction; S/N ratio 5 signal-to-noise ratio; USDA 5 U.

Poultry science, Jan 25, 2015

The objective of this research was to determine the optimal level of an encapsulated butyric acid... more The objective of this research was to determine the optimal level of an encapsulated butyric acid (ButiPEARL) based on the performance of male Cobb broilers reared to 42 d of age and to investigate its effects on intestinal morphology. Experiment 1 ( EXP 1: ) consisted of 4 treatments with 12 replicate pens that contained 45 broilers, and Experiment 2 ( EXP 2: ) consisted of 6 treatments with 8 replicate pens that contained 50 broilers. Birds were weighed by pen on d 0, 21, 35, and 42. In EXP 1, the treatments were as follows: 1) control ( C: ); 2) C + 100 g ButiPEARL/ton; 3) C + 200 g ButiPEARL/ton; and 4) C + 300 g ButiPEARL/ton. In EXP 2, the treatments were identical to EXP 1, with 2 additional treatments: 5) C + 400 g ButiPEARL/ton and 6) C + 500 g ButiPEARL/ton. In EXP 1, two 42-d-old broilers per pen were randomly selected for duodenal and jejunal tissue collection. Only the samples from the broilers fed the C or 300 g ButiPEARL treatments were analyzed for histology in EXP 1...

Virus research, 2010

Anti-coronaviral activity of a mixture of oleoresins and essential oils from botanicals, designat... more Anti-coronaviral activity of a mixture of oleoresins and essential oils from botanicals, designated QR448(a), was examined in vitro and in vivo. Treatment of avian infectious bronchitis virus (IBV) with QR448(a) reduced the virus titer as measured in two laboratory host systems, Vero E6 cells and embryonating eggs. The effect of QR448(a) on IBV in chickens was also investigated. Administering QR448(a) to chickens at a 1:20 dilution by spray, 2h before challenge with IBV was determined to be the most effective treatment. Treatment decreased the severity of clinical signs and lesions in the birds, and lowered the amount of viral RNA in the trachea. Treatment with QR448(a) protected chickens for up to 4 days post-treatment from clinical signs of disease (but not from infection) and decreased transmission of IBV over a 14-day period. Anti-IBV activity of QR448(a) was greater prior to virus attachment and entry indicating that the effect is virucidal. In addition, QR448(a) had activity a...

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Virus research, 2010

Anti-coronaviral activity of a mixture of oleoresins and essential oils from botanicals, designat... more Anti-coronaviral activity of a mixture of oleoresins and essential oils from botanicals, designated QR448(a), was examined in vitro and in vivo. Treatment of avian infectious bronchitis virus (IBV) with QR448(a) reduced the virus titer as measured in two laboratory host systems, Vero E6 cells and embryonating eggs. The effect of QR448(a) on IBV in chickens was also investigated. Administering QR448(a) to chickens at a 1:20 dilution by spray, 2h before challenge with IBV was determined to be the most effective treatment. Treatment decreased the severity of clinical signs and lesions in the birds, and lowered the amount of viral RNA in the trachea. Treatment with QR448(a) protected chickens for up to 4 days post-treatment from clinical signs of disease (but not from infection) and decreased transmission of IBV over a 14-day period. Anti-IBV activity of QR448(a) was greater prior to virus attachment and entry indicating that the effect is virucidal. In addition, QR448(a) had activity a...