scholarly journals Industry-wide surveillance of Marek’s disease virus on commercial poultry farms

2016 ◽  
Author(s):  
David A. Kennedy ◽  
Christopher Cairns ◽  
Matthew J. Jones ◽  
Andrew S. Bell ◽  
Rahel M. Salathé ◽  
...  
Keyword(s):  
Disease Virus ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Wild Type Virus ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Wild Type ◽  
Virus Prevalence ◽  
Poultry Farms ◽  
Commercial Poultry

AbstractMarek’s disease virus is a herpesvirus of chickens that costs the worldwide poultry industry over 1 billion USD annually. Two generations of Marek’s disease vaccines have shown reduced efficacy over the last half century due to evolution of the virus. Understanding where the virus is present may give insight into whether continued reductions in efficacy are likely. We conducted a three-year surveillance study to assess the prevalence of Marek’s disease virus on commercial poultry farms, determine the effect of various factors on virus prevalence, and document virus dynamics in broiler chicken houses over short (weeks) and long (years) timescales. We extracted DNA from dust samples collected from commercial chicken and egg production facilities in Pennsylvania, USA. Quantitative polymerase chain reaction (qPCR) was used to assess wild-type virus detectability and concentration. Using data from 1018 dust samples with Bayesian generalized linear mixed effects models, we determined the factors that correlated with virus prevalence across farms. Maximum likelihood and autocorrelation function estimation on 3727 additional dust samples were used to document and characterize virus concentrations within houses over time. Overall, wild-type virus was detectable at least once on 36 of 104 farms at rates that varied substantially between farms. Virus was detected in 1 of 3 broiler-breeder operations (companies), 4 of 5 broiler operations, and 3 of 5 egg layer operations. Marek’s disease virus detectability differed by production type, bird age, day of the year, operation (company), farm, house, flock, and sample. Operation (company) was the most important factor, accounting for between 12% and 63.4% of the variation in virus detectability. Within individual houses, virus concentration often dropped below detectable levels and reemerged later. These data characterize Marek’s disease virus dynamics, which are potentially important to the evolution of the virus.

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

2017 ◽  
Vol 61 (2) ◽  
pp. 153 ◽  
Author(s):  
David A. Kennedy ◽  
Christopher Cairns ◽  
Matthew J. Jones ◽  
Andrew S. Bell, ◽  
Rahel M. Salathé ◽  
...  
Keyword(s):  
Disease Virus ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Poultry Farms ◽  
Commercial Poultry

scholarly journals Marek's Disease Virus-Encoded vIL-8 Gene Is Involved in Early Cytolytic Infection but Dispensable for Establishment of Latency

2004 ◽  
Vol 78 (9) ◽  
pp. 4753-4760 ◽  
Author(s):  
Xiaoping Cui ◽  
Lucy F. Lee ◽  
Willie M. Reed ◽  
Hsing-Jien Kung ◽  
Sanjay M. Reddy
Keyword(s):  
Disease Virus ◽  
Virus Replication ◽  
Virus Titer ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Wild Type Virus ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Wild Type

ABSTRACT Marek's disease, a lymphoproliferative disease of chickens, is caused by an alphaherpesvirus, Marek's disease virus (MDV). This virus encodes a virokine, vIL-8, with general homology to cellular CXC chemokines such as interleukin-8 (IL-8) and Gro-α. To study the function of vIL-8 gene, we deleted both copies of vIL-8 residing in the terminal repeat long and internal repeat long region of the viral genome and generated a mutant virus with vIL-8 deleted, rMd5/ΔvIL-8. Growth kinetics study showed that vIL-8 gene is dispensable for virus replication in cell culture. In vivo, the vIL-8 gene is involved in early cytolytic infections in lymphoid organs, as evidenced by limited viral antigen expression of rMd5/ΔvIL-8. However, the rMd5/ΔvIL-8 virus is unimpaired in virus replication in the feather follicle epithelium. vIL-8 does not appear to be important for establishment of latency, since rMd5/ΔvIL-8 and the wild-type virus have similar viremia titers at 14 days postinfection, a period when the virus titer comes primarily from reactivated latent genomes. Nevertheless, because of the impaired cytolytic infections, the overall transformation efficiency of the virus with vIL-8 deleted is much lower, as reflected by the reduced number of transformed cells at 5 weeks postinoculation and the presence of fewer gross tumors. Importantly, the revertant virus that restored the expression of vIL-8 gene also restored the wild-type phenotype, indicating the deficient phenotypes are results of vIL-8 deletion. One of the interesting differences between the MDV vIL-8 gene and its cellular counterpart is the presence of a DKR (Asp-Lys-Arg) motif instead of ELR (Glu-Leu-Arg) preceding the invariable CXC motif. To study the significance of this variation, we generated recombinant MDV, rMd5/vIL-8-ELR, carrying the ELR motif. Both in vitro and in vivo studies revealed that the DKR motif is as competent as ELR in pathogenesis of MDV.

scholarly journals Oncogenicity of Virulent Marek's Disease Virus Cloned as Bacterial Artificial Chromosomes

2004 ◽  
Vol 78 (23) ◽  
pp. 13376-13380 ◽  
Author(s):  
Lawrence Petherbridge ◽  
Andrew C. Brown ◽  
Susan J. Baigent ◽  
Ken Howes ◽  
Melanie A. Sacco ◽  
...  
Keyword(s):  
Disease Virus ◽  
Artificial Chromosome ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Wild Type Virus ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Bac Clone ◽  
Artificial Chromosomes ◽  
Bac Clones

ABSTRACT Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that induces T-cell lymphomas in poultry. We report the construction of bacterial artificial chromosome (BAC) clones of the highly oncogenic RB-1B strain by inserting mini-F vector sequences into the US2 locus. MDV reconstituted from two BAC clones induced rapid-onset lymphomas similar to those induced by the wild-type virus. Virus reconstituted from another BAC clone that showed a 7.7-kbp deletion in the internal and terminal unique long repeat regions was nononcogenic, suggesting that the deleted region may be associated with oncogenicity. The generation of the oncogenic BAC clones of MDV is a significant step in unraveling the oncogenic determinants of this virus.

scholarly journals Molecular epidemiology of Marek’s disease virus in central Pennsylvania, USA

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Andrew S Bell ◽  
David A Kennedy ◽  
Matthew J Jones ◽  
Christopher L Cairns ◽  
Utsav Pandey ◽  
...  
Keyword(s):  
Disease Virus ◽  
Haplotype Diversity ◽  
Extended Period ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Evolutionary Potential ◽  
Gallid Herpesvirus 2 ◽  
Poultry Farms

AbstractThe evolution of Marek’s disease virus (MDV, Gallid herpesvirus 2) has threatened the sustainability of poultry farming in the past and its continued evolution remains a concern. Genetic diversity is key to understanding evolution, yet little is known about the diversity of MDV in the poultry industry. Here, we investigate the diversity of MDV on 19 Pennsylvanian poultry farms over a 3-year period. Using eight polymorphic markers, we found that at least twelve MDV haplotypes were co-circulating within a radius of 40 km. MDV diversity showed no obvious spatial clustering nor any apparent clustering by bird line: all of the virus haplotypes identified on the commercial farms could be found within a single, commonly reared bird line. On some farms, a single virus haplotype dominated for an extended period of time, while on other farms the observed haplotypes changed over time. In some instances, multiple haplotypes were found simultaneously on a farm, and even within a single dust sample. On one farm, co-occurring haplotypes clustered into phylogenetically distinct clades, putatively assigned as high and low virulence pathotypes. Although the vast majority of our samples came from commercial poultry farms, we found the most haplotype diversity on a noncommercial backyard farm experiencing an outbreak of clinical Marek’s disease. Future work to explore the evolutionary potential of MDV might therefore direct efforts toward farms that harbor multiple virus haplotypes, including both backyard farms and farms experiencing clinical Marek’s disease.

A Highly Pathogenic Marek’s Disease Virus Isolated From a Immunized to Bivalent Vaccines Chicken Farm in China

2021 ◽  
Author(s):  
Huimin Li ◽  
Zengxu Ge ◽  
Qiong Luo ◽  
Qiang Fu ◽  
Ruiai Chen
Keyword(s):  
Disease Virus ◽  
Animal Experiments ◽  
Treatment Strategies ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Potential Threat ◽  
Poultry Farms ◽  
New Treatment

Abstract Marek’s disease virus (MDV) is an important oncogenic poultry pathogen that can generally be controlled by vaccination. However, MDV still occasionally occurs on vaccinated farms owing to possible genetic variation among MDV strains as well as management-related issues. In this study, a novel MDV strain (designated LZ1309) was isolated from a poultry flock that had been previously vaccinated using the HVT plus CVI988 vaccine strains. Animal experiments showed that LZ1309 infection led higher morbidity (100%) and mortality (90%). Moreover, existing vaccines only provided partial protection against LZ1309, which protection indexes of HVT, CVI988, and HVT plus CVI988 were 68.4%, 85%, and 90%, respectively. In conclusion, we have shown that the more virulent of Marek’s disease virus existed in vaccinated with HVT plus CVI988 in poultry farms in China. And the emergence of LZ1309 poses a new potential threat to poultry farms. In future studies, the development of new treatment strategies should be of high priority.

Isolation and identification of Marek’s disease virus (MDV) from feather follicle epithelium and internal organs of diseased chickens in Dakahlia Governorate, Egypt

2019 ◽  
Vol 20 (2) ◽  
pp. 6-11
Author(s):  
Aly El-Kenawy ◽  
Mohamed El-Tholoth ◽  
Emad A
Keyword(s):  
Real Time ◽  
Disease Virus ◽  
Real Time Pcr ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Field Samples ◽  
Feather Follicle ◽  
Positive Results

In the present study, a total of 16 samples including feather follicle epithelium, ovary, spleen and kidney (4 samples for each organ) were collected from diseased chicken flocks suspected to be infected with Marek’s disease virus (MDV) at Dakahlia Governorate, Egypt during the period from October 2016 to October 2017. Each sample was pooled randomly from three to five birds (90 to 360 days old). The isolation of the suspected virus from the collected samples was carried out via chorioallantoic membranes (CAMs) of 12 days old embryonated chicken eggs (ECEs). Three egg passages were carried out for each sample. Hyperimmune serum was prepared against standard MDV. MDV in both field and egg passaged samples (after 3rd passage) was identified by agar gel precipitation test (AGPT) and indirect fluorescence antibody test (IFAT). Molecular identification of virus was carried out by conventional polymerase chain reaction (PCR) and real- time PCR in four selected samples. The results revealed that 14 samples (87.5%) including 4 (100%) samples from feather follicle epithelium, ovary and kidney and 2 (50%) samples from spleen, showed positive results in virus isolation after 3rd passage. The positive results percentage by AGPT for field samples were 50% (8 out of 16 samples), while after the 3rd passage in ECEs were 37.5% (6 out of 16 samples) and the positive results percentage by IFAT for field samples were 62.5% (10 out of 16 samples), while after the 3rd passage in ECEs were 81.25 % (13 out of 16 samples). Viral nucleic acid was detected in all selected samples by conventional and real- time PCR. The results indicate that feather follicle epithelium is the best organ for MDV detection. IFAT is superior over AGPT in virus detection. Conventional and real - time PCR could be efficiently used for molecular detection of the virus.

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