PRISM :: Browsing by Author "van der Meer, Frank"

Browsing by Author "van der Meer, Frank"

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Open Access
Activation of Toll-Like Receptor-Mediated Antiviral Response Against Infectious Laryngotracheitis Virus Infection
(2023-09-21) Mohamed Abdul Cader, Mohamed Sarjoon; Abdul-Careem, Mohamed Faizal; van der Meer, Frank; Van Marle, Guido; Gomis, Susantha
Infectious laryngotracheitis virus (ILTV) is a highly prevalent avian respiratory virus in Canada and globally, which can cause mild to severe respiratory illnesses. Although the live attenuated ILTV vaccines are commonly used for control, they pose challenges such as establishing lifelong latent infections, reactivating and shedding latent viruses, and regaining virulence in vaccine strains. Therefore, it is essential to develop novel control measures to address the limitations of current approaches. Inducing innate antiviral responses via the activation of toll-like receptors (TLRs) is a promising strategy for reducing ILTV replication. Endosomal TLRs in chickens, such as TLR7 and TLR21, recognize viral genetic materials, while surface TLRs (e.g., TLR4) primarily recognize bacterial molecules, but may also contribute to antiviral responses by recognizing viral proteins. Synthetic TLR ligands have been shown to induce antiviral responses against some avian viruses, such as avian influenza virus (AIV), infectious bursal disease virus (IBDV), ILTV, and infectious bronchitis virus (IBV). However, the impacts of in-ovo delivery of endosomal TLR7 and TLR21 ligands and surface TLR4 ligand (single-stranded (ss) RNA, cytosine-guanosine deoxynucleotides (CpG) DNA, and lipopolysaccharide (LPS), respectively) in reducing ILTV replication in chickens post-hatch through induction of antiviral responses is unknown. This thesis aimed to study the enhanced immune response following in-ovo treatment of these TLR ligands against ILTV infection in young chickens. Our hypothesis is that in-ovo delivery of these ligands will enhance antiviral immune responses and reduce ILTV replication in chickens post-hatch. Our results confirmed the following findings: Firstly, the in-ovo administration of synthetic TLR7 ligand, resiquimod, reduces ILTV shedding post-hatch, correlating with enhanced macrophage responses. Secondly, the in-ovo delivered CpG DNA stimulates cellular immune responses in multiple organs post-hatch, potentially reducing ILTV infection. Thirdly, the in-ovo LPS treatment stimulates protective antiviral responses against ILTV infection post-hatch, correlating with the expansion of macrophage population in the lungs. Overall, the studies provide insights into the mechanisms of host responses elicited following in-ovo delivery of these three TLR ligands against ILTV in chickens. The outcomes of the current studies can be helpful in fine-tuning the currently used vaccine strategies against ILTV in chicken to achieve maximum protection.
Open Access
Bacterial Respiratory Microbiota and its Role in Respiratory Health in Beef Cattle
(2020-08-12) McMullen, Christopher A.; Orsel, Karin; Timsit, Edouard; van der Meer, Frank; Alexander, Trevor W.
Bovine respiratory disease (BRD) is one of the most significant diseases facing the North American beef industry. Mounting concern over the role mass medication with antibiotics in beef production may play in antimicrobial resistance has elevated pressure on the industry to develop novel techniques and approaches for controlling BRD. This includes approaches that involve modulation of the bovine respiratory tract microbiota. The overall aim of this thesis was to investigate the role of respiratory bacterial microbiota in respiratory health and disease in beef cattle. Four studies were designed to assess different features of the respiratory microbiota using a targeted amplicon (16S rRNA gene) sequencing approach. In the first study, the bacterial microbiotas present along the entire cattle respiratory tract were described to determine which upper respiratory tract niches may contribute the most to the composition of the lung microbiota. In the second study, evolution of the nasopharyngeal bacterial microbiota of beef calves was characterized from the time of spring processing to a targeted 40 days after arrival at the feedlot. In the third study, nasopharyngeal bacterial microbiotas of beef feedlot calves raised without the use of antimicrobials that were either healthy or diagnosed with BRD were characterized and compared. In the fourth study, the progression of the nasopharyngeal and tracheal bacterial microbiotas of beef calves during the development of BRD were described. The findings of all studies were summarized and discussed. Although the nasopharynx was confirmed to likely be the most important location that should be targeted in bovine respiratory microbiota research, it appears the role of the respiratory bacterial microbiota in cattle health and disease is more complex than originally anticipated. Indeed, no common patterns of change in community composition over time, including over large periods of time and during the development of clinical BRD, were observed. These findings may affect how we research the role of the bovine microbiota in respiratory health, as well as how we design and implement novel methods for controlling, preventing, and diagnosing BRD in beef cattle.
Open Access
Comparative features of infections of two Massachusetts (Mass) infectious bronchitis virus (IBV) variants isolated from Western Canadian layer flocks
(2018-12-10) Amarasinghe, Aruna; De Silva Senapathi, Upasama; Abdul-Cader, Mohamed S; Popowich, Shelly; Marshall, Frank; Cork, Susan C; van der Meer, Frank; Gomis, Susantha; Abdul-Careem, Mohamed F
Abstract Background Infectious bronchitis virus (IBV) is one of the leading causes of mortality and morbidity in chickens. There are numerous serotypes and variants, which do not confer cross protection resulting in failure of currently used IBV vaccines. Although variant IBV isolates with major genetic differences have been subjected to comparative studies, it is unknown whether minor genetic differences in IBV variants within a serotype are different in terms of pathogenesis and eliciting host responses. Two Massachusetts (Mass) variant IBV isolates recovered from commercial layer flocks in the Western Canadian provinces of Alberta (AB) and Saskatchewan (SK) were compared genetically and evaluated for their pathogenicity, tissue distribution and ability to recruit and replicate in macrophages. Results Although whole genome sequencing of these two Mass IBV isolates showed low similarity with the M41 vaccinal strain, they had an identical nucleotide sequence at open reading frames (ORFs) 3a, 3b, envelop (E), matrix (M), 5a and 5b. The rest of the ORFs of these 2 IBV isolates showed 99.9% nucleotide similarity. However, upon experimental infection, we found that the IBV isolate originating from AB was different to the one that originated in SK due to higher tracheal lesion scores and lower lung viral replication and lower genome loads in cecal tonsils. Nevertheless, both IBV isolates elicited host responses characterized by significant macrophage recruitment to the respiratory tract and there was evidence that both IBV isolates replicated within tracheal and lung macrophages. Conclusions Overall, this study shows that Mass variant IBV isolates, although possessing minor genetic variations, can lead to significant differences in pathogenicity in young chickens. Further studies are required to investigate the pathogenicity of these two Mass variant IBV isolates in laying hens.
Open Access
Compartmental Hepatitis B Virus (HBV) Evolution, Replication and Infectivity in vivo and ex vivo
(2017) Gao, Shan; Coffin, Carla S; Lee, Samuel S.; Duan, Zhongping; Van Marle, Guido; van der Meer, Frank
Hepatitis B Virus (HBV) is classically considered a hepatotropic virus, however, the presence of different HBV genomic molecules in lymphoid cells and tissues support its lymphotropic nature. Our previous studies showed that HBV evolved in a compartment- and disease phase-specific fashion. However, the effect of nucleos/tide analogue (NA) therapy on HBV evolution and replication in different compartments (i.e., liver, plasma and peripheral blood mononuclear cell (PBMC)) is unknown, as well as the replicative competence and infectious capacity of PBMC-derived HBV. We hypothesize that HBV replicating in lymphoid cells is infectious, and the HBV evolves in PBMC and/or plasma in chronic hepatitis B (CHB) patients under the influence of NA therapy or host immune pressure (i.e., fulminant hepatitis B). The study on HBV replication and genetic evolution in PBMC, liver and plasma of CHB patients under NA therapy revealed the HBV evolution varied between three compartments both before and after treatment. NA had little effect on HBV cccDNA level and persistence of mRNA in PBMC. The study on HBV genetic features in CHB carriers with acute-on-chronic liver failure (ACLF) revealed the frequent immune escape mutations with clusters of surface gene variants possibly associated with development of fulminant hepatitis B. Mitogen stimulation in PBMC of CHB patients revealed presence of replicating HBV, which can be upregulated in PBMC and exhibited infectious capacity to HepaRG cells in vitro. In summary, our data suggests potent NAs have little effect on HBV cccDNA in liver and PBMC, which highlights the need for continued suppressive antiviral therapy. The HBV evolution varied between different compartments in CHB patients under NA therapy. Distinct variants in HBV surface gene were found to be associated with HBV fulminant hepatitis. Moreover, HBV residing in lymphoid cells is increased after mitogen stimulation of PBMC and infectious to a hepatocyte cell line. The study furthers our understanding of HBV lymphotropism, role on viral persistence and the pathogenesis of chronic hepatitis B.
Open Access
The Development of a Bovine Leukemia Virus Control Program
(2019-12-13) Kuczewski, Alessa Evelyn Traute; van der Meer, Frank; Orsel, Karin; Barkema, Herman W.; Mason, Steve; Erskine, Ronald J.; Fourichon, Christine; Lashewicz, Bonnie M.
North American dairy herds are commonly infected with bovine leukemia virus (BLV), with production-limiting effects, reduced animal welfare and consumer concerns. The overall goal of this thesis was the development of an adaptable on-farm BLV control program. To summarize important background knowledge and understand all aspects of BLV control, I performed the following: 1) Available literature concerning BLV transmission and control was reviewed and summarized. 2) Five commercially available ELISA were evaluated and compared, using 160 serum samples from Alberta cattle. 3) Economic impacts of BLV and its control were evaluated by creating an economic model of an average Alberta dairy farm. 4) Motivators and barriers for Alberta dairy farmers to change behavior on farm and implement BLV control measures were investigated by analyzing conversations with farmers as well as veterinarians. 5) In those conversations, dairy farmers’ and veterinarians’ opinions toward various BLV control measures were sought to adjust the BLV control program. 6) Based on findings, a risk assessment tool was designed to identify and weigh on-farm behavior that could cause transmission of BLV between animals. When this risk assessment tool was used on 11 Alberta dairy farms, its results, in combination with serum test results, led to the recommendation of tailored best-management practices aimed at preventing BLV transmission between animals. Implementation, within-herd prevalence, and seroconversions were measured. 7) Finally, all findings were summarized and discussed. In conclusion, recommendations for BLV control have not changed over a long interval, as general principles remain relevant. Additionally, identification of BLV-infected animals is easy and reliable. Although BLV control relies on financial investments, it has an overall economic net benefit. Motivating farmers to implement BLV control is dependent on knowledge and control measures considered feasible by the farmer. Finally, implementation of on-farm BLV control reduced within-herd BLV prevalence for the majority of participating farms.
Open Access
Development of Intranasal Bacterial Therapeutics to Mitigate the Bovine Respiratory Pathogen Mannheimia haemolytica
(2019-11) Amat, Samat; van der Meer, Frank; Alexander, Trevor W.; Buret, Andre G.; De Buck, Jeroen M.; McAllister, Tim
The emergence of multidrug-resistant pathogens associated with bovine respiratory disease (BRD) presents a significant challenge to the beef industry, as antibiotic administration is commonly used to prevent and control BRD in commercial feedlot cattle in North America. Thus, developing antibiotic alternatives such as bacterial therapeutics (BTs) to mitigate BRD is needed. Recent studies suggest that the nasopharyngeal (NP) microbiota, particularly lactic acid-producing bacteria (LAB), are important to bovine respiratory health and may be a source of BTs for the inhibition of BRD pathogens. The research presented in this thesis aimed to develop intranasal BTs to mitigate the BRD pathogen Mannheimia haemolytica and promote NP microbiota stability in feedlot cattle. Results from Study 1 showed that commercial probiotic bacteria were able to inhibit M. haemolytica growth and its adherence to epithelial cells. Study 2 revealed that the NP microbial community structure and relative abundance of LAB families underwent significant changes when cattle transported from the farm to an auction market, then to feedlot. Many of the LAB families were inversely correlated with the BRD-associated Pasteurellaceae family, and isolates from Lactobacillaceae, Streptococcaceae and Enterococcaceae families inhibited growth of M. haemolytica in vitro. This study provided evidence of potential antagonistic competition taking place between LAB and BRD-associated pathogens within the respiratory tract. Following these studies, using a targeted approach based on criteria evaluating M. haemolytica inhibition, adherence to turbinate cells, and immunomodulation, 6 Lactobacillus strains from an initial group of 178 bacterial isolates originating from nasopharynx of cattle were identified as the best BT candidates (Study 3). Intranasal inoculation of these BTs reduced colonization by M. haemolytica and induced modulation of respiratory microbiota in dairy calves experimentally challenged with M. haemolytica (Study 4). Finally, the longitudinal effects of intranasally administered BTs on the NP microbiota and the prevalence of BRD pathogens including Mannheimia were evaluated in post-weaned beef calves (Study 5). A single dose of intranasal BTs induced longitudinal modulation of the NP microbiota while showing no adverse effects on animal health and growth performance. With further characterization of inoculant dose and time of inoculation, the BTs may have potential for application as an antimicrobial alternative for mitigation of M. haemolytica in beef cattle.
Open Access
The Economic Impact of Infectious Bronchitis on the Canadian Poultry Industry
(2022-09) Phuntsho, Karma; Hall, David; Careem, Faizal; van der Meer, Frank
Infectious bronchitis is a common, highly contagious, acute, and economically important viral disease of chickens caused by infectious bronchitis virus (IBV), a gammacoronavirus. It affects the respiratory system, reproductive organs, and kidneys. Morbidity is 100%, and mortality can go well up to 30%, while egg production drops by up to 50% or more depending upon secondary infection by bacterial pathogens. Emerging IBV variants have led to outbreaks in vaccinated flocks due to a lack of cross-protective immunity, which represents a concern for producers. It is imperative that we assess the economic impact of IBV on the Canadian poultry industry to make important decisions on control and mitigation. I hypothesized that vaccination to prevent infectious bronchitis (IB) in poultry layers would have net positive economic benefits for Canadian poultry producers. A multiple scenario framework with Monte Carlo simulation and benefit-cost analysis was applied. The economic impact of IB on layer farms in Canada was examined by setting up models of Canadian layer poultry farms using data from Agriculture and Agri-Food Canada, scientific papers, the internet, and industry sources to perform simulations for various revenue classes across a range of IBV infection scenarios while considering possible control and prevention options. The results show that the impact of IB outbreaks on Canadian poultry industry is estimated to be around 207 billion CAD annually. The high benefit-cost ratios (5-9) from adopting IB vaccines suggest that vaccination as a preventive strategy would be highly cost effective. The study demonstrated the value of vaccination as a preventive or mitigation strategy against potential losses due to IBV. Understanding the extent of economic losses IB outbreaks cause to layer producers would inform the development of timely and cost-effective disease control and preventive measures in order to minimize the impact of IB on egg and chicken production.
Open Access
Epitope Mapping of Bovine Viral Diarrhea Virus Antigens E1, E2, Erns, and NS3 using Phage Display and Peptide Scanning
(2020-12-21) Bremner, William T. R.; van der Meer, Frank; Schryvers, Anthony Bernard; Coffin, Carla S.; van Marle, Guido
Bovine viral diarrhea virus is a cattle pathogen with global distribution, and substantial economic impact. Control of viral transmission is challenging by the lifelong viral shedding by persistently infected (PI) animals, and the significant diversity of the virus. While surveillance and removal of PI animals is the primary focus of control programs, insight into the antigenicity of the virus could be valuable for developing broadly protective vaccines to reduce the spread of the virus within farms and in this way the incidence of persistently infected animals (PI’s). This study aims to characterise the viral proteins of BVDV which elicit specific antibody responses. These proteins are the surface glycoproteins E1, E2 and Erns, as well as the non-structural protein NS3. This work employs the techniques of phage display, and peptide scanning to identify epitope structures on these four antigens and puts them into the context of existing structural models. Linear epitopes of potential interest for future vaccine development were identified on each of the four antigens. While attempts at characterizing conformational epitopes highlighted shortcomings in the computational workflow for such efforts, valuable insight into the limitations and future directions are drawn.
Open Access
Helminth infections in primary school children and ruminants from two elevations in Ngorongoro Conservation Area, Tanzania
(2019-01-25) Eltantawy, Manar; Orsel, Karin; van der Meer, Frank; Hatfield, Jennifer M.; Kutz, Susan J.
Intestinal helminths are a major health concern, particularly in developing countries like Tanzania. Vulnerability of primary school children and domestic ruminants to helminth infections in the Ngorongoro Conservation Area (NCA), Tanzania is not well-known. Therefore, the overall aim of this thesis was to characterize parasitism, including: prevalence, intensity, and biodiversity, in children and domestic ruminants from two ecozones in the NCA. Using coprological examinations, soil-transmitted helminths were identified in children and associations with ecozone, gender, age and body mass index were analyzed. In domestic ruminants, the same associations as well as associations with body condition score (BCS) and FAMACHA-anemia score were analyzed. In general, prevalence was high, with diversity and intensity generally highest in the high-elevation ecozone. Impact of various variables on parasitism parameters are helpful in developing evidence-based control of helminth infections and reduce impacts on health of children and domestic ruminants.
Open Access
Impact on feeding behavior of beef calves during preconditioning on ranch and commingling on arrival at the feedlot
(2022-01-24) Hodder, Abigail; Orsel, Karin; Pajor, Ed; van der Meer, Frank
Preconditioning refers to management practices implemented at the ranch to promote an easier transition to the feedlot; it is known to improve the health and welfare of beef calves. For this thesis, feeding behaviour and activity of preconditioned calves was studied from the ranch to feedlot and compared to other sources of calves, with a specific focus on the impact of bunk exposure on feeding behaviour at the feedlot. Behavioural observations were used to determine bunk attendance and CowManager® technology for time spent “eating”, “ruminating”, and “activity” (active and not active) of preconditioned, ranch-sourced, and auction-derived calves. At the ranch, bunk attendance was significantly improved for preconditioned calves between all consecutive days except days 4 and 5. Furthermore, preconditioned calves had increased bunk attendance and time spent eating at the feedlot compared to other calf sources. Preconditioned calves spent less time active, and there was no significant difference between calf sources in time spent ruminating. These results were similar when comparing preconditioned and auction-derived calves within commingled pens, providing evidence that preconditioned calves outperformed auction-derived calves during the first week after arrival at the feedlot.
Open Access
Infectious laryngotracheitis infection in chickens raised in Western Canada: Molecular characterization and vaccine efficacy studies
(2021-07-30) Barboza Solis, Catalina; Abdul Careem, Faizal; van der Meer, Frank; Fonseca, Kevin
Genomic surveillance of circulating infectious laryngotracheitis virus (ILTV) in specific geographical areas is vital for the control of the disease caused by ILTV, infectious laryngotracheitis (ILT). ILTV is endemic in backyard flocks in some Canadian provinces including Alberta (AB). Sporadic outbreaks of ILTV are reported throughout Canada in both commercial and non-commercial poultry flocks. However, there is a lack of information on the molecular nature of circulating ILTV strains associated with ILT in Canada. Vaccines are used for the control of ILT, and vaccination is employed only in certain provinces due to concerns of limitations of the currently available vaccines. In AB, only breeder flocks are vaccinated routinely in addition to a portion of the backyard flocks. Out of the two commercially available vaccines, the recombinant viral vector vaccines are considered the safest. This is due to their lack of bird-to-bird transmission and reversion to a virulent form. The first part of the thesis work was focussed on genotyping ILTV isolates linked to ILT clinical cases in AB and British Columbia (BC). Through partial sequencing of open reading frame (ORF) a and b using Sanger sequencing technology, we were able to genotype 27 ILTV isolates from AB and 5 ILTV isolates from BC. We demonstrated that the most common genotype causing ILT outbreaks in AB were chicken embryo origin (CEO) vaccine revertant ILTV strains and then, wild-type ILTV strains. In BC, we identified CEO vaccine and CEO revertant ILTV strains as cause of ILT outbreaks. The second part of this thesis was focussed on determining if recombinant herpesvirus of turkeys- laryngotracheitis (rHVT-LT) commercial vaccine could protect chickens from ILT induced by a wild-type ILTV strain isolated from AB. Our results showed that the rHVT-LT can decrease viral shedding though the oropharyngeal route. However, it did not mitigate clinical signs at the peak of the disease, and it failed to reduce viral replication in the feather tips. Overall, the work described in the thesis contributed to the knowledge on ILTV molecular epidemiology and vaccine-mediated control of ILT.
Open Access
Investigations into Macrophage-Infectious Bronchitis Virus (IBV) Interaction and Shell-less Egg Syndrome
(2018-08-29) Amarasinghe, Aruna; Abdul-Careem, Mohamed Faizal; van der Meer, Frank; Cork, S. C.; Gilch, Sabine; Gomis, Susantha Muhandiramge
Infectious bronchitis virus (IBV) is a coronavirus and infects chickens globally causing economic losses. The disease caused by IBV is known as infectious bronchitis (IB) and is prevalent in commercial broiler and layer chickens and breeder flocks in Canada. The control of IB relies on vaccination done on the day of hatch and then several times during the grower period depending on the purpose of rearing the chickens. Although the vaccine-induced immunity protects chickens from production losses induced by IBV infection, vaccine failures are frequent. Given the issues in current IB control measures, sustainable control measures developed understanding the host-IBV interaction is required. The studies conducted in the thesis focused in two major areas; 1) understanding the interaction between IBV and host immune system mainly macrophages and 2) investigating the role of IBV in a recently emerged concern of Western Canadian table-egg layer industry, shell-less egg syndrome (SES). The work described in chapter 2 of the thesis led to the finding that IBV replicates in avian macrophages in vivo and in vitro. In vitro, we showed that IBV not only targets macrophages leading to productive infection but also affects selected functions of macrophages, particularly the production of nitric oxide (NO). As shown in chapter 3, IBV infection upregulates the expression of interleukin (IL)-1β in both tracheal and lung tissues. An additional observation made was that there was a signiﬁcant association between the IBV genome load and macrophage recruitment in lungs. Overall, we found that macrophages can act as a source of cytokines, which is beneficial against IBV infection. However, the ability of IBV to replicate within macrophage by decreasing selected immune functions can be detrimental to the host. Chapter 4 provides details of our work leading to the elucidation of the etiology of SES. First, molecular characterization showed that about 70% of the IBV strains isolated from layer flocks affected with SES in Western Canada were Massachusetts (Mass) genotype. Infection of layer chickens with one of the Mass IBV isolate induced shell-less eggs. The work of chapter 5 compared two Mass IBV isolates recovered from Western Canadian layer flocks for whole genome variations and documented the differences in pathogenicity, tissue distribution, and macrophage response. The knowledge generated in the thesis increased the understanding of IBV-macrophage interaction, documented the IBV genotypes observable in Western Canada layer flocks and elucidated the etiology of SES observed in layer operations in Canada.
Open Access
Investigations of Methanobrevibacter spp. Culture to Enable Archaea Virus Propagation, and Comparison of the Efficacy of Individual Bacteriophages and their Cocktails against Escherichia coli O157
(2022-01-06) Fletcher, Jane; van der Meer, Frank; Niu, Dongyan; McAllister, Tim
Viruses that target prokaryotes are a growing area of interest for control of pathogens and other detrimental microorganisms. Archaeal viruses were identified as an option for the mitigation of methane produced by Methanobrevibacter ruminantium, which lives in ruminants such as cattle. In this study we tested three protocols to culture Methanobrevibacter spp. While a PCR was able to confirm the presence of M. ruminantium in these cultures, we could not achieve replicable growth. Unfortunately, an anti-methanogen virus could not be isolated from rumen fluid, and the culture of the archaea was found to be challenging. Another microbial target, Escherichia coli, was also explored in this study. Phages are used to control pathogenic E. coli, however, while phages can be used as support or as an alternative to antibiotic therapy, pre-existing or induced anti-phage mutations in the targeted bacteria can reduce the efficacy of this approach. Phage cocktails have been used as a strategy to reduce the likelihood that phage resistance would develop. However, in some cases, individual phages were found to be more effective at lysing bacteria and at reducing the frequency of resistance development. Therefore, we tested individual (T1, T4, T5, and rV5) and cocktail phage treatments against six strains of E. coli O157, including EDL933, R508N, CO281-31N, E32511, H4420N, and E318N. EDL933 was selected for further experiments as this is a well characterized human pathogenic strains. Our results showed that T5 and cocktail T1+T4+T5+rV5 treatments were effectively lysing bacteria, however, we have strong indications that phage resistance developed in both individual and cocktail-exposed EDL933. Cocktail T1+T4+rV5 was more effective at lysing EDL933 compared to T1, T4, or rV5 treatments. Initially the concentration of T1 in T1+T4+rV5, and T5 in cocktail T1+T4+T5+rV5 decreased before increasing to the levels of replication observed in individual treatments. T1 in T1+T4+rV5 decreased over time until it was not detectable. Sequencing of exposed strains and the phages is needed to reveal the genetic basis of resistance. More research into strategic combinations of phages, based on receptor usage or lytic activity, is required to increase the susceptibility of pathogenic E. coli to phages or antibiotics.
Embargo
Kupffer Cells In Action: Understanding The Mechanisms Of Hepadnaviral Persistence
(2023-06) Al-Yasiri, Layla; Coffin, Carla S.; Jenne, Craig N.; van der Meer, Frank
Hepatitis B virus (HBV) is the prototypical member of Hepadnaviridae family, and a causative agent of liver disease. Despite the availability of a vaccine, an estimated 1.5 million new individuals become infected each year. HBV can establish persistent infection in hepatocytes, which can disrupt hepatic homeostasis. Kupffer cells (KCs) are liver-resident macrophages that act as the first of line of defense against infectious agents. Woodchuck hepatitis virus (WHV) is a member of Hepadnaviridae. North American woodchucks (Marmota monax) infected with WHV present a natural immunocompetent model and demonstrate comparable infection outcomes and progression to hepatocellular carcinoma. We hypothesized that KC absence in acute viral hepatitis leads to chronicity by impacting virus processing and immune responses. To investigate this, we sought to uncover the early host-virus interactions in acute WHV infection. We designed and optimized in-house WHV and woodchuck-specific assays to assess intrahepatic and systemic virus presence following WHV challenge (<24 hours) and infection (6 weeks). An intravital imaging protocol was developed to capture real-time events in a living woodchuck using purified and fluorescently labelled WHV. Clodronate liposome-mediated depletion of KCs in woodchucks was performed to evaluate pre-acute challenge and acute infection in either the presence or absence of KCs. Intravital imaging of woodchucks challenged with WHV showed first appearance of virus in the liver within 30 seconds and capture by KCs within 5-10 minutes. In addition, depletion of KCs did not impact the localization of WHV during the initial hour or 24 hours of challenge. Assessment of WHV markers, serology and liver histology revealed differences in viral and biochemical markers between the KC-depleted and non-depleted animals over the initial 6 weeks. KC depletion, prior to acute WHV infection, resulted in faster onset of acute hepatitis (elevated liver enzymes) and greater suppression of WHV DNA (in circulation and intrahepatically). However, there was no difference in WHV DNA suppression between KC-depleted and non-depleted cohorts after 6 weeks p.i, as all assayed woodchucks achieved suppression of plasma WHV DNA. This may suggest that KCs normally operate under tolerogenic conditions to prevent hepatocyte damage and hepatitis, allowing for greater viral replication and immune evasion.
Open Access
The modification and evaluation of an ELISA test for the surveillance of Mycobacterium avium subsp. paratuberculosis infection in wild ruminants
(BioMed Central, 2013-01-09) Pruvot, Mathieu; Forde, Taya L; Steele, Jillian; Kutz, Susan J; De Buck, Jeroen; van der Meer, Frank; Orsel, Karin
Open Access
Molecular characterization and pathogenicity studies of Canadian infectious laryngotracheitis virus isolates
(2021-02-02) Perez Contreras, Ana Paulina; Abdul-Careem, Mohamed Faizal; Fonseca, Kevin; van der Meer, Frank
The extensive use of live-attenuated vaccines to control the upper respiratory tract viral infection in chicken known as infectious laryngotracheitis (ILT), has been associated with a surge in vaccine-related ILT outbreaks. It is documented that these ILT outbreaks are due to the regaining of virulence of the vaccine viruses due to multiple bird to bird passages following vaccination. These vaccine-originated infectious laryngotracheitis virus (ILTV) isolates are known as vaccine revertants. An additional concern is that the multiple live-attenuated vaccine ILTV and wild-type ILTV can recombine, resulting in ILTV strains with higher pathogenicity. To date, little is known about the molecular nature of the Canadian ILTV. The objectives of the present thesis work are to, 1) molecularly characterize the ILTV associated with ILT outbreaks in poultry flocks in Canada using a whole genome sequence approach and 2) study the pathogenicity of representative ILTV isolates in vivo. In achieving objective 1, It was found that most of the ILTV isolates of Canadian origin used in this study were genetically related to chicken embryo origin (CEO) live-attenuated vaccine ILTV strains. Evidence of recombination involving commonly used live-attenuated ILT vaccines was also detected in an ILTV isolate belonging to the British Columbia province. A second recombination event was found this time involving an ILTV isolate belonging to Alberta. This Alberta ILTV strain acted as a parental strain along with another live-attenuated ILT vaccine strain to give rise to an ILTV strain previously isolated in United States (US) territory. In objective 2, the pathogenicity of two wild-type and one CEO vaccine revertant ILTV isolates was compared, by infecting specific pathogen free chickens along with age-matched mock infected controls. We also used naïve contact chickens in order to determine the transmission potential of these ILTV isolates. It was found that the tested CEO vaccine revertant ILTV isolate can induce not only severe disease but also to transmit more efficiently than the wild-type ILTV isolates used for this study.
Open Access
Molecular characterization of economically important poultry viruses in western Canada
(2020-12-04) Palomino-Tapia, Victor A.; Abdul-Careem, Mohamed Faizal; Sellers, Holly S.; van der Meer, Frank; Mitevski, Darko
Avian Reovirus (ARV), Chicken Astrovirus (CAstV), and Hemorrhagic Enteritis Virus (HEV) are important enteric pathogens affecting poultry production around the world. These agents are the causative agents of Viral Arthritis (VA), White Chick Syndrome (WCS), and Hemorrhagic Enteritis (HE), respectively. In meat-type chickens, pathogenic strains of ARV can replicate in the joints leading to edema, inflammatory cell infiltrate, and fibrosis, which results in rupture of tendons. Similarly, pathogenic strains of CAstV can cause transient increase in mid to late embryo mortality, reducing hatchability between 4-68%, with some hatched birds exhibiting pale plumage; these “white chicks” (WCS) usually die within the first week of life. In turkeys, HEV infection has two presentations: 1) A clinical disease consisting on gastrointestinal hemorrhages, depression and immunosuppression (Clinical HE); and 2) subclinical infection, consisting in immunosuppression and causing economical losses due to secondary infections and plant condemnations. In recent years, these diseases have gained importance in western Canada as a result of the economic losses sustained from these infections in: a) feed conversion, b) high number of culls/first week mortality, c) secondary bacterial infections, c) processing plant condemnations; and d) costly disruptions to the Canadian Supply Management system. This thesis focuses on molecular characterization of ARV, CAstV, and HEV obtained either from clinical samples (ARV, CAstV), or from cases suspected to have subclinical infection (HEV) in poultry farms located in western Canada. The biological samples from chickens (ARV, CAStV) and turkeys (HEV) were collected from cases submitted for post-mortem examination and diagnosis to Poultry Health Services (PHS), a private poultry consulting firm, located in Airdrie, Alberta, western Canada. Further studies are required to assess the virulence of these isolates for understanding their impact in the western Canada Poultry Industry and for the implementation or enhancement of vaccination practices.
Open Access
Molecular Investigation of Wildlife Herpesvirus and Parapoxvirus: Benefits and Limitations of Genetic Characterization of dsDNA Viruses from Tissues
(2019-12-18) Dalton, Chimoné Stefni; van der Meer, Frank; Abdul-Careem, Mohamed Faizal; Kutz, Susan J.; Ruckstuhl, Kathreen E.
Wildlife populations can be reservoirs or victims of pathogens shared with humans and/or domestic animals. Most diseases at the wildlife-livestock interface are caused by viruses. Herpesviridae and Parapoxviridae are families of important double-stranded DNA (dsDNA) viruses that have been implicated in diseases of wildlife, domestic animals, and humans resulting from spill-over or zoonotic transmission, yet still little is known about viruses circulating in wildlife. Wildlife health surveillance is a primary tool for the management of zoonotic diseases, the control of diseases of domestic animals, and the preservation of wildlife populations. Studies herein conduct molecular surveillance of herpesviruses (HV) and orf virus (a parapoxvirus) through diagnostic polymerase-chain reactions (PCR), sequencing, and phylogenetic analysis using tissues of various wildlife animal species in Canada. The viral DNA polymerase (DPOL) gene is an effective target for the detection and characterization of HV present in infected animals. Previously uncharacterized HV were characterized in marten across Canada, and Reindeer gamma-HV 1 was characterized in caribou from different herds. Phylogenetic analysis suggests HV have coevolved with their wildlife host at a species level. Detection of orf virus was most successful when targeting the viral immunodominant envelope protein gene: B2L. Orf virus was detected in muskoxen on Victoria Island in areas managed by the Northwest Territories (NT) and Nunavut (NU), and on the adjacent mainland of NU, Canada. Orf virus was present in males and females, from calf to adulthood, indicating this virus represents a disease threat for muskoxen. Next-generation sequencing was performed directly on the DNA extracted from tissues of four clinically infected, geographically distant muskoxen in our study area. Phylogenetic analysis revealed Muskox orf virus (MxOV), to be unique from known orf viruses. This thesis documents the diversity of HV circulating in wildlife, increases our awareness of limitations when using tissues for molecular surveillance, increases our understanding of orf virus infection in muskoxen, and highlight areas of much-needed research. Methodologies herein can be adapted for the surveillance of other dsDNA viruses, while the data directly contribute to the database of HV and orf virus sequences in Canadian wildlife that provide context for new or emerging pathogens.
Open Access
Myoviridae as Part of Cattle Fecal Microbiome
(2019-03-18) Rincón García, Mónica; van der Meer, Frank; Bachofen, Claudia; Orsel, Karin; Timsit, Édouard; Hynes, Michael F.
Double-stranded deoxyribonucleic acid (dsDNA) phages from the order of Caudovirales are the most abundant viruses in the microbiome of the mammalian digestive tract. There is increasing awareness of the role of phages in modulating bacterial composition in digestive compartments. Mammalian digestive microbiomes are generally dominated by members of the Bacteroidetes and Firmicutes phyla. Moreover, phages from the Siphoviridae family (order Caudovirales) are the most abundant members in the rumen of cattle and large intestine of humans, horses and pigs. However, there is a knowledge gap regarding composition of the virome in the large intestine of cattle. To facilitate these studies, suitable methods to analyze bovine fecal sample for virus content are needed. Therefore, the objective of this thesis was to establish appropriate methodologies and evaluate fecal samples from various sources. Two virus particle purification (VPP) procedures, namely filtration and cesium chloride (CsCl) ultracentrifugation were compared, using electron microscopy (EM), polymerase chain reaction (PCR) and metagenomic analyses. In total, 39 cattle fecal samples were processed. Metagenomic analysis was the most suitable methodology for measuring relative abundance (RA) and diversity of Myoviridae in fecal samples from two beef and two dairy cattle. Overall, numbers of phage members of the order Caudovirales was higher compared to other dsDNA viruses, with Myoviridae being the most abundant family within this order. Furthermore, a functional procedure to estimate total viral dsDNA virome in feces was developed. In conclusion, this thesis includes methods to detect and characterize phages in cattle feces, with generation of novel data that improve understanding of viral diversity in fecal microbiomes.
Open Access
Options to Prevent Rabies in Cattle in Bhutan
(2018-03-09) Rinchen, Sangay; Cork, S. C.; van der Meer, Frank; Hall, David C.
Rabies is endemic in the southern regions of Bhutan. Frequent spillover in cattle threatens the livelihoods of marginal farmers and poses significant public health threats with a high cost to the government for outbreak response and post-exposure prophylaxis in humans. The objectives of this research were to 1) assess the risk of rabies reintroduction into the rabies low-risk zone of Bhutan, 2) describe and compare Knowledge, Attitudes, and Practices about rabies among cattle owners in high and low-risk areas, and 3) assess the economic benefits of vaccinating cattle against rabies in high-risk areas. We observed that the risk of rabies reintroduction into the low-risk zone was above negligible highlighting the need to enhance risk-mitigation measures. The observation of a lack of comprehensive knowledge about rabies among survey participants underlines the need to enhance rabies education programs. Our analysis also indicated that vaccinating cattle in high-risk areas could be a beneficial option to prevent rabies in cattle.