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Marek´s disease
Marek's disease is a highly contagious viral disease of poultry characterized by T-cell lymphomas and peripheral nerve enlargement. Standard criteria used for diagnosis include history, clinical signs, gross necropsy, and histopathology. Although no treatment is available, current vaccines are highly protective. Chickens are the most important natural host for Marek's disease virus (MDV), a highly cell-associated but readily transmitted alphaherpesvirus with lymphotropic properties of gammaherpesviruses. Quail can be naturally infected, and turkeys can be infected experimentally. However, severe clinical outbreaks of Marek's disease in commercial turkey flocks, with mortality from tumors reaching 40%–80% between 8 and 17 weeks of age, were reported in France, Israel, and Germany. In some of these cases, the affected turkey flocks were raised in proximity to broilers. Turkeys are also commonly infected with turkey herpesvirus (HVT), an avirulent strain related to Marek's disease virus that is commonly used as a Marek's disease vaccine in chickens.
1. Introduction Marek’s disease virus (MDV) is an oncogenic and highly contagious alpha herpesvirus in chickens [1]. This virus is considered a major global challenge in the poultry industry and is estimated to cause annual losses of approximately USD 1–2 billion [2]. Protective vaccines against Marek’s disease (MD) have been widely used since 1969 [3]. Due to the evolution of viral strains selecting for higher virulence, the need to develop vaccines with...
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Maricarmen García (University of Georgia) invites you to the 14th International Symposium on Marek's Disease and Avian Herpesviruses (July 12-14, 2024) in St. Louis, USA, where experts will discuss molecular biology, vaccines, and new technologies related to these diseases....
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January 28, 2025
United States - Georgia - Atlanta
Dear poultry scientists, I would like to start with the new subject regarding possible vaccination failure in MD prophylaxis. From my actual experience nowadays in spite of frequent use of bivalent vaccines against MD (Rispens+HVT) or (SB1+HVT) the MDV strains with raised virulence are isolated from field cases of the disease. I know in some cases this may be due to the low hygiene conditions in farms. However I also consider in some cases farmers apply double vaccination with bivalent...
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INTRODUCTION
Although MD is in general well controlled by vaccination in ovo or at one d of age, MD remains a concern for several reasons. First of all, vaccination practices are often suboptimal resulting in some vaccine breaks. Proper use of standard operating procedures at the hatchery remains essential for optimal protection and has been the topic of many presentations. The short-term financial gain by...
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I. INTRODUCTION Marek’s disease virus (MDV) and infectious laryngotracheitis virus (ILTV) are two economically important viruses of subfamily Alphaherpesvirinae. MDV is an extremely contagious virus which can cause severe oncogenic changes in viscera and tissues and high mortality in chicken while ILTV causes serious respiratory disease in chickens. Routine surveillance of MDV in poultry dust by quantitative PCR (qPCR) has been successfully used by industry for...
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Karel Schat (Cornell University) talked about Marek's Disease and Infectious Bursal Disease when discussing this subject, during IPPE 2020 in Atlanta, USA....
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Introduction Regulatory T cells (Tregs) are critical for maintenance of immune-homeostasis and immunological tolerance by enforcing negative regulation on T helper (Th) cells. Transcription factor Foxp3 (Foxp3) is a lineage specific factor for human and murine CD4 + CD25 + Treg cells and is crucial for Treg development and function. TGF-beta can bind to the surface of human Foxp3 + Treg cells via GARP (LRRC32) a membrane anchoring molecule, and...
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1 Introduction Characterized after its human orthologue (Herpes Simplex Virus; HSV a DNA containing virus), Marek’s disease virus (MDV), or Gallid herpesvirus 2 (GaHV-2), the etiologic agent for Marek’s disease (MD) is an alpha-herpes virus that targets avian species (Gallus gallus domesticus) where it establishes chronic infection. Notably recognized as a multifaceted disease, MD is characterized based on immunosuppression, neurological disorders and neoplastic...
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What is it? Marek's disease (MD) is the most commonly diagnosed disease in backyard chickens. Many types of birds can be affected, but chickens seem to be the most susceptible. Marek's disease is caused by a herpes virus that results in tumors in various parts of the bird. Once infected, the birds become carriers for life. The virus is present everywhere in the environment where chickens are raised. The virus does not...
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T-lymphocytes are central targets of Marek’s disease, a major chicken disease induced by the oncogenic alphaherpesvirus Marek’s disease virus (MDV). T-lymphocyte infection is also associated with immunosuppression and virus latency. To decipher viral morphogenesis in T-lymphocytes, we used the recombinant vRB-1B 47EGFP marker virus to generate a new lymphoblastoid cell line, 3867K, that exhibited typical properties of other MDV-transformed chicken...
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WHY VACCINATE? Vaccination is an effective means to prevent and/or reduce the adverse effects of specific diseases in poultry. Poultry refers to birds that people keep for their use, and generally includes chicken, turkey, duck, goose, quail, pheasant, pigeon, guinea fowl, pea fowl, ostrich, emu and rhea. Disease-causing organisms can be classified, smallest to largest, as viruses, mycoplasma, bacteria, fungi, protozoa, and parasites....
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Dr. Schat talks about the main causes of immunosuppresive diseases and about the strategies to prevent and control immunosuppresive viruses. He also gives his opinon about the evolution of Marek`s disease and the results of the use of the vaccines against chicken anemia virus....
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Lost in the Market Uncertainty Caused by the Outbreak
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Introduction Velogenic Newcastle Disease (ND), a dreadful poultry disease caused by a paramyxovirus type-I (Newcastle Disease Virus - NDV), continues to be an important threat to the modern poultry industry all over the world (4). An effective control of ND consists primarily of good biosecurity practices, preventive vaccination of flocks and the culling of infected birds and birds at risk of being infected. Vaccination...
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it is one of aneoplastic viral disease primarly affect chicken and rarely affect turkey and firstly detection of the virus occur at year of 1980 by ( dr jozef Marek) and the virus is belongs to Herpes virus of DNA viruses this viruses characheterized by the infiltration of neoplastic cells of cells forming lymphocyt in many organs as nerves trank and internal organs and most of the virus type are antigenically related to each other and greatly differs according...
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The impact of extruded soybean processing temperatures conditions on broiler’s ileal and cecal microbiota composition and function
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AVIAN DISEASES 58:345–358, 2014 Received 16 April 2014; Accepted 1 June 2014; Published ahead of print 1 June 2014 Abstract Chickens may be infected with three different oncogenic viruses: avian leukosis virus (ALV), reticuloendotheliosis virus (REV), and Marek’s disease herpesvirus (MDV). Several epidemiological studies have suggested a link...
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52 wks age of flocks affected with MD outbreak ....
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Marek’s disease virus (MDV; species Gallid herpesvirus 2, genus Mardivirus, family Herpesviridae [5, 21]) is one of the most contagious agents in poultry production. Consequently, Marek’s disease (MD) has a huge economic impact [15, 17, 22, 25]. Recently, increasing incidence of MD caused by virulent MDV strains with increased pathogenicity has been observed [2, 8, 22, 25, 27]. Initially, MDV that is present in poultry farm dust infects the host via...
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Introduction Marek’s disease (MD) still represents a serious threat for the commercial production of chickens, turkeys, and Japanese quail. In spite of worldwide vaccination MD presents one of the most economically important threat for poultry producers. The annual loss caused by the disease incidence reaches US$1 billion (12). MD is manifested by T-cell lymphomas causing immunosuppression, paralysis, and...
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