16 research outputs found

    Analysis of whole-genome sequences of infectious laryngotracheitis virus isolates from poultry flocks in Canada : evidence of recombination

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    Infectious laryngotracheitis virus (ILTV) is a herpes virus that causes an acute respiratory disease of poultry known as infectious laryngotracheitis (ILT). Chicken embryo origin (CEO) and tissue culture origin (TCO) live attenuated vaccines are routinely used for the control of ILT. However, vaccine virus is known to revert to virulence, and it has been recently shown that ILT field viral strains can undergo recombination with vaccinal ILTV and such recombinant ILT viruses possess greater transmission and pathogenicity potential. Based on complete or partial genes of the ILTV genome, few studies genotyped ILTV strains circulating in Canada, and so far, information is scarce on whole-genome sequencing or the presence of recombination in Canadian ILTV isolates. The objective of this study was to genetically characterize the 14 ILTV isolates that originated from three provinces in Canada (Alberta, British Columbia and Quebec). To this end, a phylogenetic analysis of 50 ILTV complete genome sequences, including 14 sequences of Canadian origin, was carried out. Additional phylogenetic analysis of the unique long, unique short and inverted repeat regions of the ILTV genome was also performed. We observed that 71%, 21% and 7% of the ILTV isolates were categorized as CEO revertant, wild-type and TCO vaccine-related, respectively. The sequences were also analyzed for potential recombination events, which included evidence in the British Columbia ILTV isolate. This event involved two ILTV vaccine (CEO) strains as parental strains. Recombination analysis also identified that one ILTV isolate from Alberta as a potential parental strain for a United States origin ILTV isolate. The positions of the possible recombination breakpoints were identified. These results indicate that the ILTV wild-type strains can recombine with vaccinal strains complicating vaccine-mediated control of ILT. Further studies on the pathogenicity of these ILTV strains, including the recombinant ILTV isolate are currently ongoing

    Genotyping of Infectious Laryngotracheitis Virus (ILTV) isolates from Western Canadian provinces of Alberta and British Columbia based on partial Open Reading Frame (ORF) a and b

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    Infectious laryngotracheitis virus (ILTV) causes an acute upper respiratory disease in chickens called infectious laryngotracheitis (ILT). Live attenuated vaccines are effective in disease control; however, they have residual virulence, which makes them able to replicate, cause disease and revert to the original virulent form. Information is scarce on the molecular nature of ILTV that is linked to ILT in Canada. This study aims to determine whether isolates originating from ILT cases in Western Canada are a wild type or vaccine origin. Samples submitted for the diagnosis of ILT between 2009–2018 were obtained from Alberta (AB, n = 46) and British Columbia (BC, n = 9). For genotyping, a Sanger sequencing of open reading frame (ORF) a and b was used. A total of 27 from AB, and 5 from BC samples yielded a fragment of 1751 base pairs (bp). Three of the BC samples classified as group IV (CEO vaccine strains) and 2 as group V (CEO revertant). Of the AB samples, 22 samples clustered with group V, 3 with group VI (wild type), and 2 with group VII, VIII, and IX (wild type). Overall, 17 non-synonymous single nucleotide polymorphisms (SNPs) were detected. Further studies are underway to ascertain the virulence and transmission potential of these isolates

    Evaluation of recombinant Herpesvirus of Turkey Laryngotracheitis (rHVT-LT) Vaccine against Genotype VI Canadian Wild-Type Infectious Laryngotracheitis Virus (ILTV) Infection

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    In Alberta, infectious laryngotracheitis virus (ILTV) infection is endemic in backyard poultry flocks; however, outbreaks are only sporadically observed in commercial flocks. In addition to ILTV vaccine revertant strains, wild-type strains are among the most common causes of infectious laryngotracheitis (ILT). Given the surge in live attenuated vaccine-related outbreaks, the goal of this study was to assess the efficacy of a recombinant herpesvirus of turkey (rHVT-LT) vaccine against a genotype VI Canadian wild-type ILTV infection. One-day-old specific pathogen-free (SPF) White Leghorn chickens were vaccinated with the rHVT-LT vaccine or mock vaccinated. At three weeks of age, half of the vaccinated and the mock-vaccinated animals were challenged. Throughout the experiment, weights were recorded, and feather tips, cloacal and oropharyngeal swabs were collected for ILTV genome quantification. Blood was collected to isolate peripheral blood mononuclear cells (PBMC) and quantify CD4+ and CD8+ T cells. At 14 dpi, the chickens were euthanized, and respiratory tissues were collected to quantify genome loads and histological examination. Results showed that the vaccine failed to decrease the clinical signs at 6 days post-infection. However, it was able to significantly reduce ILTV shedding through the oropharyngeal route. Overall, rHVT-LT produced a partial protection against genotype VI ILTV infection

    Pathogenic and transmission potential of wildtype and chicken embryo origin (CEO) vaccine revertant infectious laryngotracheitis virus

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    Infectious laryngotracheitis (ILT) is an infectious upper respiratory tract disease that impacts the poultry industry worldwide. ILT is caused by an alphaherpesvirus commonly referred to as infectious laryngotracheitis virus (ILTV). Vaccination with live attenuated vaccines is practiced regularly for the control of ILT. However, extensive and improper use of live attenuated vaccines is related to vaccine viruses reverting to virulence. An increase in mortality and pathogenicity has been attributed to these vaccine revertant viruses. Recent studies characterized Canadian ILTV strains originating from ILT outbreaks as related to live attenuated vaccine virus revertants. However, information is scarce on the pathogenicity and transmission potential of these Canadian isolates. Hence, in this study, the pathogenicity and transmission potential of two wildtype ILTVs and a chicken embryo origin (CEO) vaccine revertant ILTV of Canadian origin were evaluated. To this end, 3-week-old specific pathogen-free chickens were experimentally infected with each of the ILTV isolates and compared to uninfected controls. Additionally, naïve chickens were exposed to the experimentally infected chickens to mimic naturally occurring infection. Pathogenicity of each of these ILTV isolates was evaluated by the severity of clinical signs, weight loss, mortality, and lesions observed at the necropsy. The transmission potential was evaluated by quantification of ILTV genome loads in oropharyngeal and cloacal swabs and tissue samples of the experimentally infected and contact-exposed chickens, as well as in the capacity to produce ILT in contact-exposed chickens. We observed that the CEO vaccine revertant ILTV isolate induced severe disease in comparison to the two wildtype ILTV isolates used in this study. According to ILTV genome load data, CEO vaccine revertant ILTV isolate was successfully transmitted to naïve contact-exposed chickens in comparison to the tested wildtype ILTV isolates. Overall, the Canadian origin CEO vaccine revertant ILTV isolate possesses higher virulence, and dissemination potential, when compared to the wildtype ILTV isolates used in this study. These findings have serious implications in ILT control in chickens

    Biopolymer-Based hydrogels for agriculture applications: Swelling behavior and slow release of agrochemicals

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    Hydrogels are cross-linked polymers that can absorb and hold largeamounts of water and aqueous solutions due to the presence of hydrophilic functional groups in their 3D network. These materials also serve as vehicles of different active compounds because they can regulate their release rate. Because of such properties, hydrogels are currently used in many areas including agriculture, mainly as water retention agents for soil conditioning, and as carriers of agrochemicals for their slow or sustained-release. However, most of the hydrogels currently available on the market are based on polyacrylamide and acrylate derivatives, which means that they are not completely biodegradable, i.e. are considered as potential soil contaminants and present certain degree of toxicity. In this context, the development of biodegradable hydrogels for their use in agriculture is gaining interest worldwide. Biopolymers such as chitosan, cellulose, alginate and their derivatives are being explored due to their biocompatibility, biodegradability and low cost. Briefly, in this chapter, recent studies on biopolymer-based hydrogels for their use in agriculture are discussed in terms of their synthesis, swelling behavior, as well as their uses for slow and controlled release of agrochemicals.Fil: Tomadoni, Bárbara María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Casalongue, Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin
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