Industry-Wide Surveillance of Marek's Disease Virus on Commercial Poultry Farms

Kennedy, David; Cairns, Christopher; Jones, Matthew; Bell, Andrew S.; Salathé, Rahel; Baigent, Susan J.; Nair, Venugopal; Dunn, Patricia A.; Read, Andrew F.

doi:10.1637/11525-110216-reg.1

Cited by 42 publications

(47 citation statements)

References 39 publications

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“…Our previous surveillance on MDV dynamics has revealed that virus concentrations in dust tend to form U-shaped trajectories (Kennedy et al, 2017). We attributed this to dilution of virus early in the rearing period when few birds are shedding virus-contaminated dust followed by increasing concentration of virus later in the rearing period when many birds are shedding virus-contaminated dust (Kennedy et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

“…These data were originally collected as part of a surveillance study quantifying the spatial and temporal variation of MDV across farms in Pennsylvania (Kennedy et al, 2017). We use two representative datasets from that study: the data from Farm A House 1, and the data from Farm E House 4 (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…We treated 100 virus copies per mg of dust as the limit of detection by qPCR, because below this concentration, virus detection is unreliable (Kennedy et al, 2017). Using the longitudinal data from Kennedy et al (2017), we found that the probability of detection in biological replicates can be well described by a probit regression of the mean log 10 VCN/mg of dust plus 1. Using a generalized linear model with binomial data and a probit link we found an intercept of −2.206 and a slope of 1.555 (Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Yet the ecology of MDV is poorly understood. This is perhaps most clearly exemplified by the conventional wisdom that the virus is ubiquitously found on industrialized poultry farms (Office International des-Epizooties, 2010; Dunn, 2013), despite recent surveillance data suggesting that the virus may not be present on a large fraction of farms (Groves et al, 2008; Wajid et al, 2013; Walkden-Brown et al, 2013; Bettridge et al, 2014; Kennedy et al, 2015b, 2017; Ralapanawe et al, 2015). …”

Section: Introductionmentioning

confidence: 99%

“…The concentration of MDV in dust can vary several orders of magnitude between farms and within farms over time (Walkden-Brown et al, 2013; Kennedy et al, 2017). The underlying cause of this variation is unknown.…”

Section: Introductionmentioning

confidence: 99%

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Modeling Marek's disease virus transmission: A framework for evaluating the impact of farming practices and evolution

2018

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Marek’s disease virus (MDV) is a pathogen of chickens whose control has twice been undermined by pathogen evolution. Disease ecology is believed to be the main driver of this evolution, yet mathematical models of MDV disease ecology have never been confronted with data to test their reliability. Here, we develop a suite of MDV models that differ in the ecological mechanisms they include. We fit these models with maximum likelihood using iterated filtering in ‘pomp’ to data on MDV concentration in dust collected from two commercial broiler farms. We find that virus dynamics are influenced by between-flock variation in host susceptibility to virus, shedding rate from infectious birds, and cleanout efficiency. We also find evidence that virus is reintroduced to farms approximately once per month, but we do not find evidence that virus sanitization rates vary between flocks. Of the models that survive model selection, we find agreement between parameter estimates and previous experimental data, as well as agreement between field data and the predictions of these models. Using the set of surviving models, we explore how changes to farming practices are predicted to influence MDV-associated condemnation risk (production losses at slaughter). By quantitatively capturing the mechanisms of disease ecology, we have laid the groundwork to explore the future trajectory of virus evolution.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling Marek's disease virus transmission: A framework for evaluating the impact of farming practices and evolution

2018

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Newly detected mutations in the Meq oncogene and molecular pathotyping of very virulent Marek’s disease herpesvirus in Tunisia

et al. 2020

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Marek's disease (MD) is a contagious avian viral disease that is responsible for large economic losses to farmers. The disease is caused by Marek's disease virus (species Gallid alphaherpesvirus 2), which causes neurological lesions, immune suppression, and tumor proliferation of lymphoid cells that invade a large number of organs and tissues. Despite widespread vaccination, Marek's disease virus (MDV), has shown a continuous increase in its virulence and has acquired the ability to overcome immune responses induced by vaccines. In the present study, the oncogenic serotype MDV-1 was detected by real-time PCR in DNA samples extracted from organs developing tumor infiltrations. Identification of the pathotype based on a 132-bp tandem repeat and sequencing and phylogenetic analysis of the Meq gene and its encoded protein allowed classification of the isolated viruses as "very virulent", with two new and unique mutations in the Meq gene resulting in amino acid substitutions. Sequencing of pp38, vIl-8, UL1 and UL44 genes did not reveal any new mutations that were characteristic of the Tunisian isolates or correlated with virulence. These results raised concerns about the ability of HVT and CVI988 vaccines, which are currently used in Tunisia and other countries, to protect chickens against highly virulent virus strains.

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Critical roles of non-coding RNAs in lifecycle and biology of Marek’s disease herpesvirus

Teng

Zhu

Yao

et al. 2023

Sci. China Life Sci.

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Over the past two decades, numerous non-coding RNAs (ncRNAs) have been identified in different biological systems including virology, especially in large DNA viruses such as herpesviruses. As a representative oncogenic alphaherpesvirus, Marek’s disease virus (MDV) causes an important immunosuppressive and rapid-onset neoplastic disease of poultry, namely Marek’s disease (MD). Vaccinations can efficiently prevent the onset of MD lymphomas and other clinical disease, often heralded as the first successful example of vaccination-based control of cancer. MDV infection is also an excellent model for research into virally-induced tumorigenesis. Recently, great progress has been made in understanding the functions of ncRNAs in MD biology. Herein, we give a review of the discovery and identification of MDV-encoded viral miRNAs, focusing on the genomics, expression profiles, and emerging critical roles of MDV-1 miRNAs as oncogenic miRNAs (oncomiRs) or tumor suppressor genes involved in the induction of MD lymphomas. We also described the involvements of host cellular miRNAs, lincRNAs, and circRNAs participating in MDV life cycle, pathogenesis, and/or tumorigenesis. The prospects, strategies, and new techniques such as the CRISPR/Cas9-based gene editing applicable for further investigation into the ncRNA-mediated regulatory mechanisms in MDV pathogenesis/oncogenesis were also discussed, together with the possibilities of future studies on antiviral therapy and the development of new efficient MD vaccines.

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Industry-Wide Surveillance of Marek's Disease Virus on Commercial Poultry Farms

Abstract: Marek's disease (MD) is a lymphomatous and neuropathic disease of domestic fowl caused by an alphaherpesvirus, designated Marek's disease virus (MDV), belonging to the genus

Cited by 42 publications

References 39 publications

Modeling Marek's disease virus transmission: A framework for evaluating the impact of farming practices and evolution

Modeling Marek's disease virus transmission: A framework for evaluating the impact of farming practices and evolution

Newly detected mutations in the Meq oncogene and molecular pathotyping of very virulent Marek’s disease herpesvirus in Tunisia

Critical roles of non-coding RNAs in lifecycle and biology of Marek’s disease herpesvirus

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