Effect of Vaccination with Herpesvirus of Turkeys (HVT) on Horizontal Spread of Marek's Disease Herpesvirus

Purchase, H. G.; Okazaki, W.

doi:10.2307/1588710

Cited by 67 publications

(33 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The MD vaccines have all been “imperfect vaccines”, which are unable to induce a sterile immunity in the vaccinated host. The vaccine protects the host from developing signs associated with the disease, but does not prevent infection and will allow the virus to replicate within the host (Purchase & Okazaki, 1971). Therefore, vaccinated chickens can become infected with MDV, and once infected, they can transmit it.…”

Section: Introductionmentioning

confidence: 99%

The industrialization of farming may be driving virulence evolution

Rozins

Day

2016

Evolutionary Applications

View full text Add to dashboard Cite

Farming practices have changed dramatically over the years. The industrialization of farming has provided parasites with an abundance of hosts and is thought to have influenced parasite evolution. For example, the parasite that causes the highly contagious poultry disease, Marek's disease, has evolved over the past 60 years into a highly virulent pathogen. It is assumed that the industrialization of the industry and vaccination have selected for more virulent strains of the virus. Here, with the use of an impulsive differential equation model, we investigate how modern broiler farm practices could independently lead to virulence evolution. Our model suggests that longer cohort durations and more densely stocked barns both select for less virulent strains of the virus. Our model also suggests that if intensive cleaning between cohorts does not rid the barn of disease, it may drive evolution and cause the disease to become more virulent.

show abstract

Section: Introductionmentioning

confidence: 99%

The industrialization of farming may be driving virulence evolution

Rozins

Day

2016

Evolutionary Applications

View full text Add to dashboard Cite

show abstract

“…MD costs the worldwide commercial poultry industry $1 billion to $2 billion in losses annually (1); therefore, control of MD is vital for economic viability. Vaccines have been successfully used to control MD since 1970 with the introduction of HVT, a related turkey herpesvirus (2). Since then, additional vaccines with better efficacy have been introduced to combat field strains that evolved to overcome existing vaccinal protection (3).…”

mentioning

confidence: 99%

Characterizing the Molecular Basis of Attenuation of Marek's Disease Virus via In Vitro Serial Passage Identifies De Novo Mutations in the Helicase-Primase Subunit Gene UL5 and Other Candidates Associated with Reduced Virulence

Hildebrandt

Dunn²,

Perumbakkam

et al. 2014

J Virol

View full text Add to dashboard Cite

Marek's disease (MD) is a lymphoproliferative disease of chickens caused by the oncogenic Gallid herpesvirus 2, commonly known as Marek's disease virus (MDV). MD vaccines, the primary control method, are often generated by repeated in vitro serial passage of this highly cell-associated virus to attenuate virulent MDV strains. To understand the genetic basis of attenuation, we used experimental evolution by serially passing three virulent MDV replicates generated from an infectious bacterial artificial chromosome (BAC) clone. All replicates became completely or highly attenuated, indicating that de novo mutation, and not selection among quasispecies existing in a strain, is the primary driving force for the reduction in virulence. Sequence analysis of the attenuated replicates revealed 41 to 95 single-nucleotide variants (SNVs) at 2% or higher frequency in each population and several candidate genes containing high-frequency, nonsynonymous mutations. Five candidate mutations were incorporated into recombinant viruses to determine their in vivo effect. SNVs within UL42 (DNA polymerase auxiliary subunit) and UL46 (tegument) had no measurable influence, while two independent mutations in LORF2 (a gene of unknown function) improved survival time of birds but did not alter disease incidence. A fifth SNV located within UL5 (helicase-primase subunit) greatly reduced in vivo viral replication, increased survival time of birds, and resulted in only 0 to 11% disease incidence. This study shows that multiple genes, often within pathways involving DNA replication and transcriptional regulation, are involved in de novo attenuation of MDV and provides targets for the rational design of future MD vaccines. IMPORTANCEMarek's disease virus (MDV) is a very important pathogen in chickens that costs the worldwide poultry industry $1 billion to $2 billion annually. Marek's disease (MD) vaccines, the primary control method, are often produced by passing virulent strains in cell culture until attenuated. To understand this process, we identified all the changes in the viral genome that occurred during repeated cell passage. We find that a single mutation in the UL5 gene, which encodes a viral protein necessary for DNA replication, reduces disease incidence by 90% or more. In addition, other candidate genes were identified. This information should lead to the development of more effective and rationally designed MD vaccines leading to improved animal health and welfare and lower costs to consumers.

show abstract

“…However, even with vaccines, estimated annual losses worldwide from MD owing to meat condemnation and reduced egg production are $1-2 billion (15). Although vaccination prevents the formation of lymphoma and other MD symptoms, it does not prevent MDV infection, replication, or horizontal spread (16). Moreover, even though available vaccines protect chickens against the disease, MD still remains a threat owing to increasingly frequent outbreaks caused by highly virulent strains of MDV combined with the incomplete immunity that is elicited by vaccination (17)(18)(19).…”

Section: Rationale For Enhanced Genetic Resistancementioning

confidence: 99%

Integrated Genomic Approaches to Enhance Genetic Resistance in Chickens

Cheng

Kaiser

Lamont

2013

Annu. Rev. Anim. Biosci.

View full text Add to dashboard Cite

The chicken has led the way among agricultural animal species in infectious disease control and, in particular, selection for genetic resistance. The generation of the chicken genome sequence and the availability of other empowering tools and resources greatly enhance the ability to select for enhanced disease resistance via genetic markers and to understand more deeply the biological basis of host resistance. In this review, we discuss how integrated genomic approaches are able to identify specific genes and genetic markers associated with disease resistance, give select examples of contemporary work involving various genomic strategies to identify disease resistance genes, and finish by giving some final thoughts on predicted applications in the near future. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. AbstractThe chicken has led the way among agricultural animal species in infectious disease control and, in particular, selection for genetic resistance. The generation of the chicken genome sequence and the availability of other empowering tools and resources greatly enhance the ability to select for enhanced disease resistance via genetic markers and to understand more deeply the biological basis of host resistance. In this review, we discuss how integrated genomic approaches are able to identify specific genes and genetic markers associated with disease resistance, give select examples of contemporary work involving various genomic strategies to identify disease resistance genes, and finish by giving some final thoughts on predicted applications in the near future.

show abstract

Effect of Vaccination with Herpesvirus of Turkeys (HVT) on Horizontal Spread of Marek's Disease Herpesvirus

Cited by 67 publications

References 14 publications

The industrialization of farming may be driving virulence evolution

The industrialization of farming may be driving virulence evolution

Characterizing the Molecular Basis of Attenuation of Marek's Disease Virus via In Vitro Serial Passage Identifies De Novo Mutations in the Helicase-Primase Subunit Gene UL5 and Other Candidates Associated with Reduced Virulence

Integrated Genomic Approaches to Enhance Genetic Resistance in Chickens

Contact Info

Product

Resources

About