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Journal of Virology Mar 2022Latency is a hallmark of herpesviruses, allowing them to persist in their host without virion production. Acute exposure to hypoxia (below 3% O) was identified as a...
Latency is a hallmark of herpesviruses, allowing them to persist in their host without virion production. Acute exposure to hypoxia (below 3% O) was identified as a trigger of latent-to-lytic switch (reactivation) for human oncogenic gammaherpesviruses (Kaposi's sarcoma-associated virus [KSHV] and Epstein-Barr virus [EBV]). Therefore, we hypothesized that hypoxia could also induce reactivation of Marek's disease virus (MDV), which shares biological properties with EBV and KSHV (notably oncogenic properties), in lymphocytes. Acute exposure to hypoxia (1% O) of two MDV-latently infected cell lines derived from MD tumors (3867K and MSB-1) induced MDV reactivation. A bioinformatic analysis of the RB-1B MDV genome revealed 214 putative hypoxia response element consensus sequences on 119 open reading frames. Reverse transcriptase quantitative PCR (RT-qPCR) analysis showed five MDV genes strongly upregulated early after hypoxia. In 3867K cells under normoxia, pharmacological agents mimicking hypoxia (MLN4924 and CoCl) increased MDV reactivation, but to a lower level than real hypoxia. Overexpression of wild-type or stabilized human hypoxia inducible factor 1α (HIF-1α) in MSB-1 cells in normoxia also promoted MDV reactivation. Under such conditions, the lytic cycle was detected in cells with a sustainable HIF-1α expression but also in HIF-1α-negative cells, indicating that MDV reactivation is mediated by HIF-1 in a direct and/or indirect manner. Lastly, we demonstrated by a reporter assay that HIF-1α overexpression induced the transactivation of two viral promoters, shown to be upregulated in hypoxia. These results suggest that hypoxia may play a crucial role in the late lytic replication phase observed in MDV-infected chickens exhibiting tumors, since a hypoxic microenvironment is a hallmark of most solid tumors. Latent-to-lytic switch of herpesviruses (also known as reactivation) is responsible for pathology recurrences and/or viral shedding. Studying physiological triggers of reactivation is therefore important for health to limit lesions and viral transmission. Marek's disease virus (MDV) is a potent oncogenic alphaherpesvirus establishing latency in T lymphocytes and causing lethal T lymphomas in chickens. , a second lytic phase is observed during the tumoral stage. Hypoxia being a hallmark of tumors, we wondered whether hypoxia induces MDV reactivation in latently infected T lymphocytes, like previously shown for EBV and KSHV in B lymphocytes. In this study, we demonstrated that acute hypoxia (1% O) triggers MDV reactivation in two MDV transformed T-cell lines. We provide some molecular basis of this reactivation by showing that hypoxia inducible factor 1 (HIF-1) overexpression induces MDV reactivation to an extent similar to that of hypoxia after 24 h. Hypoxia is therefore a reactivation stimulus shared by mammalian and avian oncogenic herpesviruses of different genera.
Topics: Animals; Cell Line, Tumor; Chickens; Herpesvirus 2, Gallid; Hypoxia; Hypoxia-Inducible Factor 1; Lymphoma; Marek Disease; T-Lymphocytes; Virus Activation
PubMed: 34936483
DOI: 10.1128/JVI.01427-21 -
Genes Nov 2021Marek's disease (MD) was an immunosuppression disease induced by Marek's disease virus (MDV). MD caused huge economic loss to the global poultry industry, but it also...
Marek's disease (MD) was an immunosuppression disease induced by Marek's disease virus (MDV). MD caused huge economic loss to the global poultry industry, but it also provided an ideal model for studying diseases induced by the oncogenic virus. Alternative splicing (AS) simultaneously produced different isoform transcripts, which are involved in various diseases and individual development. To investigate AS events in MD, RNA-Seq was performed in tumorous spleens (TS), spleens from the survivors (SS) without any lesion after MDV infection, and non-infected chicken spleens (NS). In this study, 32,703 and 25,217 AS events were identified in TS and SS groups with NS group as the control group, and 1198, 1204, and 348 differently expressed (DE) AS events (-value < 0.05 and FDR < 0.05) were identified in TS vs. NS, TS vs. SS, SS vs. NS, respectively. Additionally, Function enrichment analysis showed that ubiquitin-mediated proteolysis, p53 signaling pathway, and phosphatidylinositol signaling system were significantly enriched (-value < 0.05). Small structural variations including SNP and indel were analyzed based on RNA-Seq data, and it showed that the TS group possessed more variants on the splice site region than those in SS and NS groups, which might cause more AS events in the TS group. Combined with previous circRNA data, we found that 287 genes could produce both circular and linear RNAs, which suggested these genes were more active in MD lymphoma transformation. This study has expanded the understanding of the MDV infection process and provided new insights for further analysis of resistance/susceptibility mechanisms.
Topics: Alternative Splicing; Animals; Chickens; Gene Expression Profiling; Mardivirus; Marek Disease; Polymorphism, Single Nucleotide; RNA; RNA Splice Sites; RNA, Circular; Signal Transduction; Spleen
PubMed: 34946806
DOI: 10.3390/genes12121857 -
Journal of Virology Nov 2020Marek's disease virus (MDV) transforms CD4 T cells and causes a deadly neoplastic disease that is associated with metabolic dysregulation leading to atherosclerosis in...
Marek's disease virus (MDV) transforms CD4 T cells and causes a deadly neoplastic disease that is associated with metabolic dysregulation leading to atherosclerosis in chickens. While MDV-infected chickens have normal serum concentrations of cholesterol, their aortic tissues were found to have elevated concentrations of free and esterified cholesterol. Here, we demonstrate that infection of chicken embryonated fibroblasts (CEFs) with highly pathogenic MDV-RB1B increases the cellular cholesterol content and upregulates the genes involved in cholesterol synthesis and cellular cholesterol homeostasis using comprehensive two-dimensional gas chromatography-mass spectrometry and real-time PCR (RT-PCR), respectively. Using small pharmacological inhibitors and gene silencing, we established an association between MDV-RB1B replication and mevalonic acid, sterol, and cholesterol biosynthesis and trafficking/redistribution. We propose that MDV trafficking is mediated by lysosome-associated membrane protein 1 (LAMP-1)-positive vesicles based on short hairpin RNA (shRNA) gene silencing and the colocalization of LAMP-1, glycoprotein B (gB) of MDV, and cholesterol (filipin III) fluorescence signal intensity peaks. In conclusion, our results demonstrate that MDV hijacks cellular cholesterol biosynthesis and cholesterol trafficking to facilitate cell-to-cell spread in a LAMP-1-dependent mechanism. MDV disrupts lipid metabolism and causes atherosclerosis in MDV-infected chickens; however, the role of cholesterol metabolism in the replication and spread of MDV is unknown. MDV-infected cells do not produce infectious cell-free virus , raising the question about the mechanism involved in the cell-to-cell spread of MDV. In this report, we provide evidence that MDV replication depends on cholesterol biosynthesis and uptake. Interruption of cholesterol trafficking within multivesicular bodies (MVBs) by chemical inhibitors or gene silencing reduced MDV titers and cell-to-cell spread. Finally, we demonstrated that MDV gB colocalizes with cholesterol and LAMP-1, suggesting that viral protein trafficking is mediated by LAMP-1-positive vesicles in association with cholesterol. These results provide new insights into the cholesterol dependence of MDV replication.
Topics: Animals; Antigens, Viral; Chickens; Cholesterol; Herpesvirus 2, Gallid; Homeostasis; Lanosterol; Lipid Metabolism; Lipogenesis; Lysosomal Membrane Proteins; Marek Disease; Mevalonic Acid; Protein Transport; Transcription Factors; Viral Envelope Proteins; Viral Proteins; Virus Replication
PubMed: 32999035
DOI: 10.1128/JVI.01001-20 -
Journal of Dairy Science May 1989Numerous studies confirm that genes in the chicken major histocompatibility complex exert major genetic control over host resistance to autoimmune, viral, bacterial, and... (Review)
Review
Numerous studies confirm that genes in the chicken major histocompatibility complex exert major genetic control over host resistance to autoimmune, viral, bacterial, and parasitic diseases. Examples of major histocompatibility complex associations with traits of growth and reproduction in the chicken are also available. Thus, the major effects of the major histocompatibility complex on the economically important traits of disease resistance, growth, and reproduction make the major histocompatibility complex a valuable subject for intensive analysis in agricultural species. This paper examines, as a model for integration of genetics and immunology, the research on the chicken major histocompatibility complex, which confirmed its role in genetic control of disease resistance, focusing on Marek's disease, a virally induced cancer. Current knowledge of associations of the chicken major histocompatibility complex with specific disease resistance, immune response, and other economic traits are selectively reviewed. Use of major histocompatibility complex typing in the poultry industry, including speculation about future applications, is presented.
Topics: Animals; Breeding; Chickens; Immunity, Innate; Major Histocompatibility Complex; Marek Disease; Pasteurella Infections; Polymorphism, Restriction Fragment Length; Poultry Diseases
PubMed: 2568373
DOI: 10.3168/jds.S0022-0302(89)79240-7 -
Epidemics Jun 2019The industrialization of farming has had an enormous impact. To most, this impact is viewed solely in the context of productivity, but the denser living conditions and...
The industrialization of farming has had an enormous impact. To most, this impact is viewed solely in the context of productivity, but the denser living conditions and shorter rearing periods of industrial livestock farms provide pathogens with an ideal opportunity to spread and evolve. For example, the industrialization of poultry farms drove the Marek's disease virus (MDV) to evolve from a mild paralytic syndrome to a highly contagious, globally prevalent, deadly disease. Fortunately, the economic catastrophe that would occur from MDV evolution is prevented through the widespread use of live imperfect vaccines that limit disease symptoms, but fail to prevent transmission. Unfortunately, the continued rollout of such imperfect vaccines is steering MDV evolution towards even greater virulence, and the ability to evade vaccine protection. Thus, there is a need to investigate alternative economically viable control measures for their ability to inhibit MDV spread and evolution. In what follows we examine the economic viability of standard husbandry practices for their ability to inhibit the spread of both virulent MDV and very virulent MDV throughout an industrialized egg farm. To do this, we parameterize a MDV transmission model and calculate the loss in egg production due to MDV. We find that MDV strain and the cohort duration have the greatest influence on both disease burden and egg production. Additionally, our findings show that for long cohort durations, conventional cages result in the least per capita loss in egg production due to MDV infection, while Aviary systems perform best over shorter cohort durations. Finally, we find that the least per capita loss in egg production for flocks infected with the more virulent MDV strains occurs when cohort durations are sufficiently short. These results highlight the important decisions that managers will face when implementing new hen husbandry practices.
Topics: Animals; Chickens; Eggs; Food Industry; Marek Disease; Virulence
PubMed: 30745241
DOI: 10.1016/j.epidem.2019.01.004 -
Viruses Jan 2019Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that infects chickens and integrates its genome into the telomeres of latently infected cells. MDV encodes...
Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that infects chickens and integrates its genome into the telomeres of latently infected cells. MDV encodes two proteins, UL12 and UL29 (ICP8), that are conserved among herpesviruses and could facilitate virus integration. The orthologues of UL12 and UL29 in herpes simplex virus 1 (HSV-1) possess exonuclease and single strand DNA-binding activity, respectively, and facilitate DNA recombination; however, the role of both proteins in the MDV lifecycle remains elusive. To determine if UL12 and/or UL29 are involved in virus replication, we abrogated their expression in the very virulent RB-1B strain. Abrogation of either UL12 or UL29 resulted in a severe impairment of virus replication. We also demonstrated that MDV UL12 can aid in single strand annealing DNA repair, using a well-established reporter cell line. Finally, we assessed the role of UL12 and UL29 in MDV integration and maintenance of the latent virus genome. We could demonstrate that knockdown of UL12 and UL29 does not interfere with the establishment or maintenance of latency. Our data therefore shed light on the role of MDV UL12 and UL29 in MDV replication, DNA repair, and maintenance of the latent virus genome.
Topics: Animals; Cell Line; Chickens; DNA Repair; DNA Replication; DNA, Viral; Genome, Viral; Herpesvirus 2, Gallid; Marek Disease; Recombination, Genetic; Viral Proteins; Virus Latency; Virus Replication
PubMed: 30696089
DOI: 10.3390/v11020111 -
Veterinary Research 2002Genetic resistance to diseases is a multigenic trait governed mainly by the immune system and its interactions with many physiologic and environmental factors. In the... (Review)
Review
Genetic resistance to diseases is a multigenic trait governed mainly by the immune system and its interactions with many physiologic and environmental factors. In the adaptive immunity, T cell and B cell responses, the specific recognition of antigens and interactions between antigen presenting cells, T cells and B cells are crucial. It occurs through a network of mediator proteins such as the molecules of the major histocompatibility complex (MHC), T cell receptors, immunoglobulins and secreted proteins such as the cytokines and antibodies. The diversity of these proteins that mainly is due to an intrinsic polymorphism of the genes causes phenotypic variation in disease resistance. The well-known linkage of MHC polymorphism and Marek's disease resistance difference represents a classic model revealing immunological factors in resistance differences and diversity of mediator molecules. The molecular bases in any resistance variation to infectious pathogens are vaguely understood. This paper presents a review of the major immune mediators involved in resistance and susceptibility to infectious diseases and their functional mechanisms in the chicken. The genetic interaction of disease resistance with production traits and the environment is mentioned.
Topics: Animals; Chickens; Cytokines; Immunity, Innate; Immunogenetics; Immunoglobulins; Major Histocompatibility Complex; Marek Disease; Phenotype; Polymorphism, Genetic; Poultry Diseases; Receptors, Antigen, T-Cell
PubMed: 11944802
DOI: 10.1051/vetres:2002001 -
Journal of Virology Jan 2021Marek's disease virus (MDV) is an oncogenic alphaherpesvirus of chickens. The MDV genome consists of two unique regions that are both flanked by inverted repeat regions....
Marek's disease virus (MDV) is an oncogenic alphaherpesvirus of chickens. The MDV genome consists of two unique regions that are both flanked by inverted repeat regions. These repeats harbor several genes involved in virus replication and pathogenesis, but it remains unclear why MDV and other herpesviruses harbor these large sequence duplications. In this study, we set to determine if both copies of these repeat regions are required for MDV replication and pathogenesis. Our results demonstrate that MDV mutants lacking the entire internal repeat region (ΔIR) efficiently replicate and spread from cell-to-cell However, ΔIR replication was severely impaired in infected chickens and the virus caused significantly less frequent disease and tumors compared to the controls. In addition, we also generated recombinant viruses that harbor a deletion of most of the internal repeat region, leaving only short terminal sequences behind (ΔIR). These remaining homologous sequences facilitated rapid restoration of the deleted repeat region, resulting in a virus that caused disease and tumors comparable to the wild type. Therefore, ΔIR represents an excellent platform for rapid genetic manipulation of the virus genome in the repeat regions. Taken together, our study demonstrates that MDV requires both copies of the repeats for efficient replication and pathogenesis in its natural host. Marek's disease virus (MDV) is a highly oncogenic alphaherpesvirus that infects chickens and causes losses in the poultry industry of up to $2 billion per year. The virus is also widely used as a model to study alphaherpesvirus pathogenesis and virus-induced tumor development in a natural host. MDV and most other herpesviruses harbor direct or inverted repeats regions in their genome. However, the role of these sequence duplications in MDV remains elusive and has never been investigated in a natural virus-host model for any herpesvirus. Here, we demonstrate that both copies of the repeats are needed for efficient MDV replication and pathogenesis , while replication was not affected in cell culture. With this, we further dissect herpesvirus genome biology and the role of repeat regions in Marek's disease virus replication and pathogenesis.
Topics: Animals; Chickens; Genome; Herpesvirus 2, Gallid; Marek Disease; Mutation; Neoplasms; Repetitive Sequences, Nucleic Acid; Sequence Deletion; Virus Replication
PubMed: 33115875
DOI: 10.1128/JVI.01256-20 -
Viruses Feb 2023Marek's disease virus (MDV), a highly cell-associated oncogenic α-herpesvirus, is the etiological agent of T cell lymphomas and neuropathic disease in chickens known as...
Marek's disease virus (MDV), a highly cell-associated oncogenic α-herpesvirus, is the etiological agent of T cell lymphomas and neuropathic disease in chickens known as Marek's disease (MD). Clinical signs of MD include neurological disorders, immunosuppression, and lymphoproliferative lymphomas in viscera, peripheral nerves, and skin. Although vaccination has greatly reduced the economic losses from MD, the molecular mechanism of vaccine-induced protection is largely unknown. To shed light on the possible role of T cells in immunity induced by vaccination, we vaccinated birds after the depletion of circulating T cells through the IP/IV injection of anti-chicken CD4 and CD8 monoclonal antibodies, and challenged them post-vaccination after the recovery of T cell populations post-treatment. There were no clinical signs or tumor development in vaccinated/challenged birds with depleted CD4 or CD8 T cells. The vaccinated birds with a combined depletion of CD4 and CD8 T cells, however, were severely emaciated, with atrophied spleens and bursas. These birds were also tumor-free at termination, with no virus particles detected in the collected tissues. Our data indicated that CD4 and CD8 T lymphocytes did not play a critical role in vaccine-mediated protection against MDV-induced tumor development.
Topics: Animals; Marek Disease; CD8-Positive T-Lymphocytes; Chickens; Lymphoma; Herpesvirus 2, Gallid; Viral Vaccines
PubMed: 36992357
DOI: 10.3390/v15030648 -
Poultry Science May 1991Cell-mediated immune (CMI) responses to viral tumor diseases are often used as examples of the importance of antiviral and antitumor immunity in chickens. Especially,... (Review)
Review
Cell-mediated immune (CMI) responses to viral tumor diseases are often used as examples of the importance of antiviral and antitumor immunity in chickens. Especially, reticuloendotheliosis virus (REV) and Marek's disease herpesvirus (MDV) are used as models to study the development of cytotoxic T-lymphocytes against viral and tumor antigens and activation of natural killer (NK) cells. Major histocompatibility complex Class I-restricted, antiviral cytotoxic T-lymphocytes expressing CD4-/CD8+ markers are induced after infection with REV. Thus far, this is the only example of Class I-restricted cytotoxic T-lymphocytes in chickens. Antiviral cytotoxic T-lymphocytes may be induced by infection with MDV or by vaccination, but conclusive evidence has not yet been provided. Antitumor responses have not been demonstrated against REV-induced tumors. Although Marek's disease is often used as an example for the importance of antitumor immunity, there is a lack of convincing data demonstrating antitumor immunity mediated by cytotoxic T-lymphocytes. Activation of NK cells by MDV infection or vaccination is probably an important part of CMI responses against Marek's disease viral antigens but not against tumor antigens.
Topics: Animals; Birds; Immunity, Cellular; Marek Disease; Reticuloendotheliosis virus; Tumor Virus Infections
PubMed: 1649464
DOI: 10.3382/ps.0701165