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Title: The biological characterization of cells of a transplantable tumor (JMV) derived from a Marek's disease lymphoma
Creator: Stephens, Elizabeth Ann
Date: 1976
Collection: Electronic Theses & Dissertations

Title: Production, purification, and characterization of Marek's disease infected cell "A" antigen
Creator: Long, P. A. (Philip Arthur), 1934-
Date: 1973
Collection: Electronic Theses & Dissertations

Title: Purification and characterization of bacteriophage gh-1-induced deoxyribonucleic acid-dependent ribonucleic acid polymerase from Pseudomonas putida
Creator: Towle, Howard Colgate, 1947-
Date: 1974
Collection: Electronic Theses & Dissertations

Title: Cultivation in vitro of the tumor of lymphomatosis
Creator: Chrétien, Marguerite Marie A.
Date: 1951
Collection: Electronic Theses & Dissertations

Title: Identification and characterization of Marek's disease virus unique short region genes and their products
Creator: Brunovskis, Peter
Date: 1992
Collection: Electronic Theses & Dissertations

Title: Identification of candidate genes and isoforms associated with genetic resistance to Marek's disease from RNA-Seq data
Creator: Preeyanon, Likit
Date: 2014
Collection: Electronic Theses & Dissertations
Description: Marek's disease (MD) in chickens is characterized by T celllymphomas caused by the Marek's disease virus (MDV), anα-herpesvirus. MD is a major economical problem forthe poultry industry as it causes approximately $2 billionin worldwide losses annually. Although vaccination has beeneffective at preventing tumor formation, it has not beenable to prevent MDV infection or replication. Consequently,more virulent field strains have emerged over the pastdecades following the introduction of...
Show moreMarek's disease (MD) in chickens is characterized by T celllymphomas caused by the Marek's disease virus (MDV), anα-herpesvirus. MD is a major economical problem forthe poultry industry as it causes approximately $2 billionin worldwide losses annually. Although vaccination has beeneffective at preventing tumor formation, it has not beenable to prevent MDV infection or replication. Consequently,more virulent field strains have emerged over the pastdecades following the introduction of new vaccines. Poorpractices of vaccination and incomplete immunity have beenspeculated to play a role in driving the evolution of thevirus with greater virulence. Therefore, it is criticallyimportant to develop more sustainable control measures tothe disease in the long run.Development of genetically resistant chickens has been analternative approach to control the virus and a number of studieshave been conducted to identify specific genes that contribute toMD resistance. The major histocompatibility (MHC) locus has beenfound to be strongly associated with resistance or susceptibilityto MD, and several alleles have been well characterized. Non-MHCgenes also play a major role in resistance to MD. Two inbredlines (line 6 and line 7) maintained at Avian and OncologyLaboratory share the same MHC allele (B2), yetline 6 is resistant and line 7 is susceptible to MD,respectively. These two lines have been used as a model to studynon-MHC genes that contribute to resistance and susceptibility tothe disease.To identify non-MHC genes contributing resistance to MD, acomputational pipeline was developed to integrate gene modelsfrom Ensembl, de novo assembly, and reference-basedassembly (Cufflinks) of sequencing reads to construct a morecomplete set of gene models that include more completeuntranslated regions (UTRs) and isoforms predicted from RNA-Seqdata. The results from expression analysis suggest that theimmune response in line 7 is more active at the early stage ofinfection (4 days post-infection) compared to line 6.Differentially expressed genes are enriched in pathways involvedin both the innate and the adaptive immune response in line 7,whereas, only genes involved in the innate immune response aresignificantly enriched in line 6. Due to the cell-associatednature of MDV and the current model of MDV infection, the virusis thought to transfer from B cells and antigen presenting cells(APCs) to activated T cells during the lytic infection.Therefore, repressed or delayed activation of the adaptive immuneresponse in line 6 may be a key mechanism conferring MDresistance.Investigation of differential exon usage suggests that genesinvolved in the cytoskeleton pathway may play a role inrepressing the activation of the adaptive immune response.For instance, the ITGB2 gene encodes integrinβ2, a componentof several molecules including the lymphocytefunction-associated antigen 1 (LFA-1). LFA-1 is exclusivelyexpressed on the surface of leukocytes and plays animportant role in cell-to-cell contact and antigenpresentation. It could be speculated that an alternativeisoform of ITGB2 affects a function of LFA-1 and prevents Tcells from being activated by APCs or B cells resulting inthe delayed activation of the adaptive immune response orthe lower number of activated T cells, the target of MDV.The results from this study show that many genes not identifiedas differentially expressed at a gene level are differentiallyexpressed at an isoform level; therefore, they will not beidentified by gene expression analysis alone. Using the pipelinedeveloped in this study, one can iteratively incorporate ENSEMBLmodels and RNA-seq data to construct better gene models thatinclude genes and isoforms expressed in all samples and performdifferential gene and isoform expression analysis to identifygenes and isoforms that are responsible for resistance to MD.Although functions of most isoforms are not fully annotated,we have shown that methods, such as protein prediction andpathway analysis, can be used to predict the putativefunctions of the isoforms and their potential roles in MDresistance, which could open up a new direction for MDresearch. Moreover, prediction of causative cis-regulatoryelements in those genes will lead to identification ofprecise genetic factors contributing to MD resistance.
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Title: Identifying the genetic basis of attenuation in Marek's disease virus via experimental evolution
Creator: Hildebrandt, Evin
Date: 2014
Collection: Electronic Theses & Dissertations
Description: Marek's disease virus (MDV), an oncogenic alphaherpesvirus of chickens, causes up to $2 billion in loses a year due to Marek's disease (MD). Therefore control of this economically important disease is critical. The primary method to control MD is vaccination. Attenuated, or weakened, strains of MDV have been generated via repeated in vitro serial passage to generate avirulent MDV strains that have been used as successful MD vaccines. Despite introduction of several vaccines since the 1970's,...
Show moreMarek's disease virus (MDV), an oncogenic alphaherpesvirus of chickens, causes up to $2 billion in loses a year due to Marek's disease (MD). Therefore control of this economically important disease is critical. The primary method to control MD is vaccination. Attenuated, or weakened, strains of MDV have been generated via repeated in vitro serial passage to generate avirulent MDV strains that have been used as successful MD vaccines. Despite introduction of several vaccines since the 1970's, more virulent strains of MDV have evolved to break vaccinal protection. Therefore, development of new MD vaccines is necessary. To address this concern, we sought to better understand the molecular basis of attenuation in MDV to provide information that may assist in the rationale design of MD vaccines. Three attenuated replicates of a virulent MDV were serially passed in vitro for over 100 passages. DNA and RNA from attenuated viruses were deep sequenced using Illumina next-generation sequencers to identify changes in DNA sequence or expression following attenuation. Top candidate mutations identified via sequencing were used to generate seven recombinant viruses using red-mediated recombineering for mutations within UL42, UL46, UL5, two involving LORF2 and two mutations within ICP4. These recombinant viruses were tested in vivo to determine the impact of these mutations on MD incidence, in vivo replication and horizontal transmission. Point mutations within UL42, UL46, LORF2-Promoter and ICP4 did not cause observable phenotypic changes compared to the parental virus. A single point mutation within LORF2-Intron and a double mutant involving ICP4 both resulting in 100% MD in challenged birds but failed to transmit horizontally to uninfected contact birds. Finally, a point mutation within UL5 reduced MD incidence by over 90%, significantly reduced in vivo replication, and eliminated horizontal transmission. Further characterization of this UL5 point mutation determined that it increased in vitro replication in growth curves, yet head-to-head competition of the Mut UL5 virus versus parental virus showed the parental virus outcompeted the mutant virus. Furthermore, serial passage of Mut UL5 in vivo did not result in increased in MD incidence, in vivo replication or result in reversion or compensatory mutations to UL5 after passage through birds. Trials testing vaccinal protection of the Mut UL5 virus showed the virus provided partial protection against challenge with virulent MDV, yet did not exceed protection achieved through use of traditional vaccines. Therefore, use of this point mutation in combination with other candidate mutations was tested. Addition of the UL5 mutation with Delta Meq, a candidate vaccine with high protection and replication but also induces bursal-thymic atrophy (BTA), resulted in a recombinant virus that replicated at low levels and did not cause BTA, yet reduced levels of vaccinal protection, indicating an intricate relationship between replication levels, BTA and vaccinal protection. This study shows that a variety of genes are mutated during attenuation, and particularly mutations within DNA replication genes, such as UL5, appear to play an important role in attenuation. We also determined that experimental evolution is a process that not only can identify mutations involved in attenuation, but also offer protection as a vaccine to provide information for further development of MD vaccines.
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Title: Understanding the mechanisms of oncogenicity by Marek's disease virus : role of Meq oncoprotein
Creator: Subramaniam, Sugalesini
Date: 2013
Collection: Electronic Theses & Dissertations
Description: Marek's disease (MD) is one of the most economically significant diseases in chickens. It is caused by a highly oncogenic, alpha-herpesvirus named Marek's disease virus (MDV). Currently, the main strategy to control MD is vaccination. However, accumulating evidence points to increase in virulence among MDV field isolates over time, which implicates that new strains of the virus are evolving and could break vaccine protection. This necessitates better understanding of MDV-host interactions,...
Show moreMarek's disease (MD) is one of the most economically significant diseases in chickens. It is caused by a highly oncogenic, alpha-herpesvirus named Marek's disease virus (MDV). Currently, the main strategy to control MD is vaccination. However, accumulating evidence points to increase in virulence among MDV field isolates over time, which implicates that new strains of the virus are evolving and could break vaccine protection. This necessitates better understanding of MDV-host interactions, not only to elucidate the events in pathogenesis but also develop strategies for newer and more effective vaccines. One of the major unanswered questions in this area is the mechanism of tumor formation by MDV. The main objective of this project is to gain a comprehensive understanding of host genes that are transcriptionally regulated by Meq, the major oncoprotein of MDV and their relevance in genetic resistance to MD. MDV oncogenicity is largely attributed to the bZIP transcription factor Meq. Although it was discovered in the 1990s, only a few of host target genes have been described. This knowledge gap has impeded our understanding of Meq-induced tumorigenesis. Using a combination of state-of-the-art genomic techniques including ChIP-Seq and microarray analysis, a high confidence list of Meq binding sites and a global transcriptome of genes regulated by Meq was generated. Given the importance of Meq in MDV pathogenesis, we next explored the role of Meq in genetic resistance to MD. Two highly inbred chicken lines, varying in MD resistance, were infected with a virulent strain of MDV, Md5 or a mutant virus lacking Meq, Md-deltaMeq. Analysis of differentially expressed genes provided a list of Meq-dependent genes that are involved in MD resistance and susceptibility. Pathway analysis indicated that MD resistant lines were enriched for positive regulation of cell death whereas the susceptible cell lines were enriched for regulation of cell proliferation. In addition, some of the Meq-regulated pathways like ERK/MAPK signaling and Jak-STAT pathways were also involved in differential MD susceptibility. Taken together, our study provides a comprehensive analysis of how Meq interacts with cellular pathways involved in oncogenesis. In addition, this study forms the basis for selection of candidate genes that might be involved in genetic resistance to Marek's disease.
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