RÉSUMÉ
Marek's disease (MD), caused by the Marek's disease virus (MDV), is a common infectious tumor disease in chickens and was the first neoplastic disease preventable by vaccination. However, the vaccine cannot completely prevent virulent MDV infections, allowing both the vaccine and virulent MDV to coexist in the same chicken for extended periods. This study aims to investigate the changes in viral load of the very virulent strain Md5 and the rHVT-IBD vaccine in different chicken tissues using a real-time PCR assay. The results showed that the rHVT-IBD vaccine significantly reduced the viral load of MDV-Md5 in different organs, while the load of rHVT-IBD was significantly increased when co-infected with Md5. Additionally, co-infection with Md5 and rHVT-IBD in chickens not only changed the original viral load of both viruses but also affected the positive rate of Md5 at 14 days post-vaccination. The positive rate decreased from 100% to 14.29% (feather tips), 0% (skin), 33.33% (liver), 16.67% (spleen), 28.57% (thymus), 33.33% (bursa), and 66.67% (PBL), respectively. This study enhances our understanding of the interactions between HVT vector vaccines and very virulent MDV in chickens and provides valuable insights for the future development of MD vaccines.
Sujet(s)
Poulets , Co-infection , Vaccins contre la maladie de Marek , Maladie de Marek , Maladies de la volaille , Charge virale , Animaux , Maladie de Marek/virologie , Maladie de Marek/prévention et contrôle , Maladie de Marek/immunologie , Poulets/virologie , Co-infection/virologie , Co-infection/médecine vétérinaire , Maladies de la volaille/virologie , Maladies de la volaille/prévention et contrôle , Vaccins contre la maladie de Marek/immunologie , Vaccins contre la maladie de Marek/génétique , Virulence , Herpèsvirus de type 1 du dindon/immunologie , Herpèsvirus de type 1 du dindon/génétique , Vaccins synthétiques/immunologie , Vaccins synthétiques/génétique , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/immunologie , Herpèsvirus aviaire de type 2/pathogénicité , Vaccination , Vecteurs génétiques/génétiqueRÉSUMÉ
Marek's disease virus (MDV) can cause severe immunosuppression in chickens. Our previous study showed that infection with very virulent plus (vv+) MDV strains of one-day-old commercial meat-type chickens possessing maternal antibodies against MDV resulted in severe depletion of splenocytes at 28-30 days of age. In the present study, we have investigated the effect of vv+MDV strain 686 on splenic immunophenotypes at 6, 20, and 30 days post-infection (dpi). Both live and dead cells were analyzed, and the data were statistically compared to the uninfected control. The results revealed a decrease in the total live cell population starting on day 20, primarily affecting B cells, CD8ß+, and gamma delta (γδ) T cells, while the frequencies of both live and dead CD3+ and CD4+ T cells were increased. The MHC-I expression of CD3+ and CD4+ T cells was higher at 20 and 30 dpi, while the expression of MHC-II on these cells was downregulated at 6 dpi but was upregulated at 30 dpi. Collectively, these results suggest that maternal antibodies seem to delay the negative effects of vv+MDV on the splenic lymphoid populations, albeit being non-protective. Our results emphasize the importance of MD vaccination in vv+MDV endemic areas.
Sujet(s)
Poulets , Maladie de Marek , Maladies de la volaille , Rate , Animaux , Rate/immunologie , Rate/virologie , Maladie de Marek/immunologie , Maladie de Marek/virologie , Maladies de la volaille/virologie , Maladies de la volaille/immunologie , Immunophénotypage , Virulence , Lymphocytes B/immunologie , Herpèsvirus aviaire de type 2/immunologie , Herpèsvirus aviaire de type 2/génétiqueRÉSUMÉ
Marek's disease virus (MDV) is an economic concern for the poultry industry due to its poorly understood pathophysiology. Purinergic receptors (PRs) are potential therapeutic targets for viral infections, including herpesviruses, prompting our investigation into their role in MDV pathogenesis. The current study is part of an experimental series analyzing the expression of PRs during MDV infection. To address the early or short-acting P2 PR responses during natural MDV infection, we performed an "exposure" experiment where age-matched chickens were exposed to experimentally infected shedders to initiate natural infection. In addition, select non-PR regulatory gene responses were measured. Two groups of naïve contact chickens (n = 5/breed/time point) from MD-resistant (White Leghorns: WL) and -susceptible (Pure Columbian) chicken lines were housed separately with experimentally infected PC (×PC) and WL (×WL) chickens for 6 or 24 h. Whole lung lavage cells (WLLC) were collected, RNA was extracted, and RT-qPCR assays were used to measure specific PR responses. In addition, other potentially important markers in pathophysiology were measured. Our study revealed that WL chickens exhibited higher P1 PR expression during natural infection. WL chickens also showed higher expression of P1A3 and P2X3 at 6 and 24 h when exposed to PC-infected chickens. P2X5 and P2Y1 showed higher expression at 6 h, while P2Y5 showed higher expression at 6 and 24 h; regardless of the chicken line, PC chickens exhibited higher expression of P2X2, P2Y8, P2Y10, P2Y13, and P2Y14 when exposed to either group of infected chickens. In addition, MDV infection altered the expression of DDX5 in both WL and PC groups exposed to PC-infected birds only. However, irrespective of the source of exposure, BCL2 and ANGPTL4 showed higher expression in both WL and PC. The expression of STAT1A and STAT5A was influenced by time and breed, with major changes observed in STAT5A. CAT and SOD1 expression significantly increased in both WL and PC birds, regardless of the source of infection. GPX1 and GPX2 expression also increased in both WL and PC, although overall lower expression was observed in PC chickens at 24 h compared to 6 h. Our data suggest systemic changes in the host during early infection, indicated by the altered expression of PRs, DDX5, BCL2, ANGPTL4, and other regulatory genes during early MDV infection. The relative expression of these responses in PC and WL chickens suggests they may play a key role in their response to natural MDV infection in the lungs and long-term pathogenesis and survival.
Sujet(s)
Poulets , Poumon , Maladie de Marek , Récepteurs purinergiques , Animaux , Poulets/virologie , Maladie de Marek/virologie , Maladie de Marek/métabolisme , Poumon/virologie , Poumon/métabolisme , Récepteurs purinergiques/métabolisme , Récepteurs purinergiques/génétique , Maladies de la volaille/virologie , Maladies de la volaille/métabolisme , Maladies de la volaille/génétique , Herpèsvirus aviaire de type 2/physiologie , Résistance à la maladie/génétique , Prédisposition aux maladiesRÉSUMÉ
Marek's disease (MD), caused by the Marek's disease virus, is a lymphoproliferative disease in chickens that can be controlled by vaccination. However, the current vaccines can limit tumor growth and death but not virus replication and transmission. The present study aimed to evaluate host responses following intramuscular injection of an mRNA vaccine encoding gB and pp38 proteins of the MDV within the first 36 h. The vaccine was injected in low and high doses using prime and prime-boost strategies. The expression of type I and II interferons (IFNs), a panel of interferon-stimulated genes, and two key antiviral cytokines, IL-1ß and IL-2, were measured in spleen and lungs after vaccination. The transcriptional analysis of the above genes showed significant increases in the expression of MDA5, Myd88, IFN-α, IFN-ß, IFN-γ, IRF7, OAS, Mx1, and IL-2 in both the spleen and lungs within the first 36 h of immunization. Secondary immunization increased expression of all the above genes in the lungs. In contrast, only IFN-γ, MDA5, MyD88, Mx1, and OAS showed significant upregulation in the spleen after the secondary immunization. This study shows that two doses of the MDV mRNA vaccine encoding gB and pp38 antigens activate innate and adaptive responses and induce an antiviral state in chickens.
Sujet(s)
Poulets , Cytokines , Herpèsvirus aviaire de type 2 , Vaccins contre la maladie de Marek , Maladie de Marek , Animaux , Poulets/immunologie , Maladie de Marek/prévention et contrôle , Maladie de Marek/immunologie , Maladie de Marek/virologie , Vaccins contre la maladie de Marek/immunologie , Vaccins contre la maladie de Marek/administration et posologie , Vaccins contre la maladie de Marek/génétique , Cytokines/métabolisme , Cytokines/immunologie , Herpèsvirus aviaire de type 2/immunologie , Herpèsvirus aviaire de type 2/génétique , Poumon/virologie , Poumon/immunologie , Rate/immunologie , Rate/virologie , Maladies de la volaille/prévention et contrôle , Maladies de la volaille/immunologie , Maladies de la volaille/virologie , Vaccins à ARNm/immunologie , Vaccination , ARN messager/génétique , ARN messager/immunologie , Vaccins synthétiques/immunologie , Vaccins synthétiques/administration et posologie , Vaccins synthétiques/génétiqueRÉSUMÉ
Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that causes deadly lymphomas in chickens. In chickens, up to 50% of all peripheral T cells are gamma delta (γδ) T cells. Until now, their role in MDV pathogenesis and tumor formation remains poorly understood. To investigate the role of γδ T cells in MDV pathogenesis, we infected recently generated γδ T cell knockout chickens with very virulent MDV. Strikingly, disease and tumor incidence were highly increased in the absence of γδ T cells, indicating that γδ T cells play an important role in the immune response against MDV. In the absence of γδ T cells, virus replication was drastically increased in the thymus and spleen, which are potential sites of T cell transformation. Taken together, our data provide the first evidence that γδ T cells play an important role in the pathogenesis and tumor formation of this highly oncogenic herpesvirus.IMPORTANCEGamma delta (γδ) T cells are the most abundant T cells in chickens, but their role in fighting pathogens remains poorly understood. Marek's disease virus (MDV) is an important veterinary pathogen, that causes one of the most frequent cancers in animals and is used as a model for virus-induced tumor formation. Our study revealed that γδ T cells play a crucial role in combating MDV, as disease and tumor incidence drastically increased in the absence of these cells. γδ T cells restricted virus replication in the key lymphoid organs, thereby decreasing the likelihood of causing tumors and disease. This study provides novel insights into the role of γδ T cells in the pathogenesis of this highly oncogenic virus.
Sujet(s)
Poulets , Herpèsvirus aviaire de type 2 , Maladie de Marek , Réplication virale , Animaux , Poulets/virologie , Maladie de Marek/virologie , Maladie de Marek/immunologie , Herpèsvirus aviaire de type 2/pathogénicité , Herpèsvirus aviaire de type 2/immunologie , Herpèsvirus aviaire de type 2/génétique , Rate/immunologie , Rate/virologie , Rate/anatomopathologie , Récepteur lymphocytaire T antigène, gamma-delta/immunologie , Récepteur lymphocytaire T antigène, gamma-delta/génétique , Lymphocytes intra-épithéliaux/immunologie , Thymus (glande)/immunologie , Thymus (glande)/virologie , Thymus (glande)/anatomopathologie , Lymphocytes T/immunologie , Maladies de la volaille/virologie , Maladies de la volaille/immunologieRÉSUMÉ
Marek's disease (MD) is an important neoplastic disease caused by serotype 1 Marek's disease virus (MDV-1), which results in severe economic losses worldwide. Despite vaccination practices that have controlled the MD epidemic, current increasing MD-suspected cases indicate the persistent viral infections circulating among vaccinated chicken farms in many countries. However, the lack of available information about phylogeny and molecular characterization of circulating MDV-1 field strains in Taiwan reveals a potential risk in MD outbreaks. This study investigated the genetic characteristics of 18 MDV-1 strains obtained from 17 vaccinated chicken flocks in Taiwan between 2018 and 2020. Based on the sequences of the meq oncogene, the phylogenetic analysis demonstrated that the circulating Taiwanese MDV-1 field strains were predominantly in a single cluster that showed high similarity with strains from countries of the East Asian region. Because the strains were obtained from CVI988/Rispens vaccinated chicken flocks and the molecular characteristics of the Meq oncoprotein showed features like vvMDV and vv+MDV strains, the circulating Taiwanese MDV-1 field strains may have higher virulence compared with vvMDV pathotype. In conclusion, the data presented demonstrates the circulation of hypervirulent MDV-1 strains in Taiwan and highlights the importance of routine surveillance and precaution strategies in response to the emergence of enhanced virulent MDV-1.
Sujet(s)
Poulets , Herpèsvirus aviaire de type 2 , Maladie de Marek , Protéines des oncogènes viraux , Animaux , Poulets/virologie , Herpèsvirus aviaire de type 2/classification , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/pathogénicité , Maladie de Marek/virologie , Maladie de Marek/prévention et contrôle , Vaccins contre la maladie de Marek/génétique , Vaccins contre la maladie de Marek/immunologie , Protéines des oncogènes viraux/génétique , Phylogenèse , Maladies de la volaille/virologie , Maladies de la volaille/épidémiologie , Maladies de la volaille/prévention et contrôle , Taïwan/épidémiologie , Vaccination/médecine vétérinaire , Virulence/génétiqueRÉSUMÉ
Marek's disease (MD), caused by gallid alphaherpesvirus 2 (GaAHV2) or Marek's disease herpesvirus (MDV), is a devastating disease in chickens characterized by the development of lymphomas throughout the body. Vaccine strains used against MD include gallid alphaherpesvirus 3 (GaAHV3), a non-oncogenic chicken alphaherpesvirus homologous to MDV, and homologous meleagrid alphaherpesvirus 1 (MeAHV1) or turkey herpesvirus (HVT). Previous work has shown most of the MDV gC produced during in vitro passage is secreted into the media of infected cells although the predicted protein contains a transmembrane domain. We formerly identified two alternatively spliced gC mRNAs that are secreted during MDV replication in vitro, termed gC104 and gC145 based on the size of the intron removed for each UL44 (gC) transcript. Since gC is conserved within the Alphaherpesvirinae subfamily, we hypothesized GaAHV3 (strain 301B/1) and HVT also secrete gC due to mRNA splicing. To address this, we collected media from 301B/1- and HVT-infected cell cultures and used Western blot analyses and determined that both 301B/1 and HVT produced secreted gC. Next, we extracted RNAs from 301B/1- and HVT-infected cell cultures and chicken feather follicle epithelial (FFE) skin cells. RT-PCR analyses confirmed one splicing variant for 301B/1 gC (gC104) and two variants for HVT gC (gC104 and gC145). Interestingly, the splicing between all three viruses was remarkably conserved. Further analysis of predicted and validated mRNA splicing donor, branch point (BP), and acceptor sites suggested single nucleotide polymorphisms (SNPs) within the 301B/1 UL44 transcript sequence resulted in no gC145 being produced. However, modification of the 301B/1 gC145 donor, BP, and acceptor sites to the MDV UL44 sequences did not result in gC145 mRNA splice variant, suggesting mRNA splicing is more complex than originally hypothesized. In all, our results show that mRNA splicing of avian herpesviruses is conserved and this information may be important in developing the next generation of MD vaccines or therapies to block transmission.
Sujet(s)
Antigènes viraux , Mardivirus , Épissage des ARN , ARN messager , Protéines de l'enveloppe virale , Animaux , Épissage alternatif , Poulets/virologie , Herpèsvirus aviaire de type 2/génétique , Mardivirus/génétique , Mardivirus/physiologie , Maladie de Marek/virologie , ARN messager/génétique , ARN messager/métabolisme , Protéines de l'enveloppe virale/génétique , Protéines de l'enveloppe virale/métabolismeRÉSUMÉ
Marek's disease virus (MDV) vaccines were the first vaccines that protected against cancer. The avirulent turkey herpesvirus (HVT) was widely employed and protected billions of chickens from a deadly MDV infection. It is also among the most common vaccine vectors providing protection against a plethora of pathogens. HVT establishes latency in T-cells, allowing the vaccine virus to persist in the host for life. Intriguingly, the HVT genome contains telomeric repeat arrays (TMRs) at both ends; however, their role in the HVT life cycle remains elusive. We have previously shown that similar TMRs in the MDV genome facilitate its integration into host telomeres, which ensures efficient maintenance of the virus genome during latency and tumorigenesis. In this study, we investigated the role of the TMRs in HVT genome integration, latency, and reactivation in vitro and in vivo. Additionally, we examined HVT infection of feather follicles. We generated an HVT mutant lacking both TMRs (vΔTMR) that efficiently replicated in cell culture. We could demonstrate that wild type HVT integrates at the ends of chromosomes containing the telomeres in T-cells, while integration was severely impaired in the absence of the TMRs. To assess the role of TMRs in vivo, we infected one-day-old chickens with HVT or vΔTMR. vΔTMR loads were significantly reduced in the blood and hardly any virus was transported to the feather follicle epithelium where the virus is commonly shed. Strikingly, latency in the spleen and reactivation of the virus were severely impaired in the absence of the TMRs, indicating that the TMRs are crucial for the establishment of latency and reactivation of HVT. Our findings revealed that the TMRs facilitate integration of the HVT genome into host chromosomes, which ensures efficient persistence in the host, reactivation, and transport of the virus to the skin.
Sujet(s)
Poulets , Maladie de Marek , Télomère , Intégration virale , Latence virale , Animaux , Poulets/virologie , Télomère/génétique , Télomère/virologie , Maladie de Marek/virologie , Maladie de Marek/immunologie , Maladie de Marek/prévention et contrôle , Vecteurs génétiques , Herpèsvirus de type 1 du dindon/génétique , Herpèsvirus de type 1 du dindon/immunologie , Vaccins contre la maladie de Marek/immunologie , Vaccins contre la maladie de Marek/génétique , Génome viral , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/immunologie , Séquences répétées d'acides nucléiques , Maladies de la volaille/virologie , Maladies de la volaille/immunologie , Maladies de la volaille/prévention et contrôleRÉSUMÉ
The highly contagious, immunosuppressive, and cancer-causing Marek's disease virus (MDV) infects chickens. The financial costs of Marek's disease (MD) are significant for the chicken industry. In this study, a total of 180 samples from chicken farms suspected to be MDV-infected were collected. The chickens were sampled during the period between the months of October 2016 and February 2018 at Dakahlia and Damietta Governorates, Egypt. A total of 36 pooled samples were created. The prepared samples were inoculated into embryonated chicken eggs (ECEs). Indirect fluorescent antibody technique (IFAT) and ICP4 gene-based polymerase chain reaction (PCR) were used for MDV identification. For the genetic characterization of the identified virus, The ICP4 gene sequence was identified and compared with the sequences available from various regions of the world. Furthermore, the genomes of all detected MDVs were screened for the long terminal repeat (LTR) region of reticuloendotheliosis (REV) in their genomes. The results showed that 31 out of 36 pooled samples (86.1%) inoculated into ECEs displayed the characteristic pock lesions. By using IFAT and PCR to identify MDV in ECEs, positive results were found in 27 samples (75%). The Egyptian virus is thought to be genetically closely related to MDVs circulating in Ethiopia, China, and India. REV-LTR was amplified from 6 out of 27 field isolates genomes (22.2 %) while MDV vaccine strains were free from REV-LTR insertion. The integrated REV-LTRs depicted a close genetic relationship with those integrated in fowl poxvirus (FWPV) circulating in Egypt as well as those integrated in FWPVs and MDVs from China, USA, South Africa, and Australia. To the best of our knowledge, this investigation represents the first identification and characterization of REV-LTR insertions in Egyptian MDV field isolates. Given the findings above, additional research in the future seems crucial to determine how the REV-LTR insertions affect MDV pathogenesis, virulence, and insufficient vaccination protection.
Sujet(s)
Poulets , Herpèsvirus aviaire de type 2 , Maladie de Marek , Maladies de la volaille , Animaux , Maladie de Marek/virologie , Maladie de Marek/épidémiologie , Poulets/virologie , Égypte/épidémiologie , Maladies de la volaille/virologie , Maladies de la volaille/épidémiologie , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/isolement et purification , Séquences répétées terminales , Virus de la réticuloendothéliose/génétique , Virus de la réticuloendothéliose/isolement et purification , Intégration virale , Génome viralRÉSUMÉ
Marek's disease (MD) is a neoplastic disease that significantly affects the poultry industry. Long non-coding RNAs (lncRNAs) are crucial regulatory factors in various biological processes, including tumourigenesis. However, the involvement of novel lncRNAs in the course of MD virus (MDV) infection is still underexplored. Here, we present the first comprehensive characterization of differentially expressed lncRNAs in chicken spleen at different stages of MDV infection. A series of differentially expressed lncRNAs was identified at each stage of MDV infection through screening. Notably, our investigation revealed a novel lncRNA, lncRNA 803, which exhibited significant differential expression at different stages of MDV infection and was likely to be associated with the p53 pathway. Further analyses demonstrated that the overexpression of lncRNA 803 positively regulated the expression of p53 and TP53BP1 in DF-1 cells, leading to the inhibition of apoptosis. This is the first study to focus on the lncRNA expression profiles in chicken spleens during MDV pathogenesis. Our findings highlight the potential role of the p53-related novel lncRNA 803 in MD pathogenesis and provide valuable insights for decoding the molecular mechanism of MD pathogenesis involving non-coding RNA.RESEARCH HIGHLIGHTS Differentially expressed lncRNAs in spleens of chickens infected with Marek's disease virus at different stages were identified for the first time.The effects of novel lncRNA 803 on p53 pathway and apoptosis of DF-1 cells were reported for the first time.
Sujet(s)
Apoptose , Poulets , Maladie de Marek , Maladies de la volaille , ARN long non codant , Rate , Protéine p53 suppresseur de tumeur , Animaux , ARN long non codant/génétique , Maladie de Marek/virologie , Maladie de Marek/génétique , Poulets/virologie , Rate/virologie , Rate/anatomopathologie , Maladies de la volaille/virologie , Maladies de la volaille/génétique , Protéine p53 suppresseur de tumeur/génétique , Protéine p53 suppresseur de tumeur/métabolisme , Lignée cellulaire , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/physiologieRÉSUMÉ
Monitoring Marek's disease (MD) vaccination is routinely done by evaluating the load of MD vaccine in the feather pulp (FP) between 7 and 10 days of age. However, attempts in our laboratory to detect a novel CVI-LTR vaccine in the FP samples from commercial flocks failed. The objective of this study was to evaluate the most suitable tissue and age to monitor CVI-LTR vaccination. We used two different commercial CVI988 vaccines as controls. One hundred and sixty 1-day-old commercial brown layers were vaccinated with either CVI-LTR, CVI988-A, CVI988-B or remained unvaccinated. Samples of the spleen, thymus, and bursa were collected at 3, 4, 5, and 6 days of age and samples of FP were collected at 7 and 21 days for DNA isolation. Our results showed that CVI-LTR replicated earlier than CVI988 vaccines in the lymphoid organs but was not detected in the FP at either 7 or at 21 days of age. We also confirmed that either the spleen or thymus collected at 4-6 days was a suitable sample to monitor CVI-LTR vaccination in commercial flocks. Finally, we evaluated the load of oncogenic MDV DNA in five commercial flocks that were vaccinated with either CVI-LTR + rHVT or CVI988-A + rHVT. The load of oncogenic MDV DNA was evaluated at 21 days in the FP in 20 chickens per group. Our results demonstrated that CVI-LTR was more successful in reducing oncogenic MDV DNA at 21 days of age than the CVI988-A strain.RESEARCH HIGHLIGHTSCVI-LTR replicates in the thymus and spleen earlier than CVI988.CVI-LTR replicates in lymphoid organs but it cannot be detected in feather pulp.CVI-LTR reduced the load of oncogenic MDV DNA more efficiently than CVI988.
Sujet(s)
Poulets , Plumes , Vaccins contre la maladie de Marek , Maladie de Marek , Rate , Thymus (glande) , Animaux , Poulets/virologie , Maladie de Marek/prévention et contrôle , Maladie de Marek/virologie , Vaccins contre la maladie de Marek/immunologie , Rate/virologie , Plumes/virologie , Thymus (glande)/virologie , Maladies de la volaille/virologie , Maladies de la volaille/prévention et contrôle , Séquences répétées terminales , Femelle , Vaccination/médecine vétérinaire , Bourse de Fabricius/virologie , Virus de la réticuloendothéliose/génétique , Herpèsvirus aviaire de type 2/génétique , Réplication virale , ADN viral/génétiqueRÉSUMÉ
Microbial genomes from ancient chickens uncover the drivers of pathogenicity.
Sujet(s)
Poulets , Génome viral , Mardivirus , Maladie de Marek , Animaux , Poulets/microbiologie , Virulence/génétique , Maladie de Marek/histoire , Maladie de Marek/virologie , Mardivirus/génétique , Mardivirus/pathogénicitéRÉSUMÉ
The pronounced growth in livestock populations since the 1950s has altered the epidemiological and evolutionary trajectory of their associated pathogens. For example, Marek's disease virus (MDV), which causes lymphoid tumors in chickens, has experienced a marked increase in virulence over the past century. Today, MDV infections kill >90% of unvaccinated birds, and controlling it costs more than US$1 billion annually. By sequencing MDV genomes derived from archeological chickens, we demonstrate that it has been circulating for at least 1000 years. We functionally tested the Meq oncogene, one of 49 viral genes positively selected in modern strains, demonstrating that ancient MDV was likely incapable of driving tumor formation. Our results demonstrate the power of ancient DNA approaches to trace the molecular basis of virulence in economically relevant pathogens.
Sujet(s)
Poulets , Herpèsvirus aviaire de type 2 , Maladie de Marek , Animaux , Poulets/virologie , Herpèsvirus aviaire de type 2/classification , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/pathogénicité , Lymphomes/virologie , Maladie de Marek/histoire , Maladie de Marek/virologie , Virulence/génétique , PhylogenèseRÉSUMÉ
IMPORTANCE: Marek's disease virus (MDV) is a ubiquitous chicken pathogen that inflicts a large economic burden on the poultry industry, despite worldwide vaccination programs. MDV is only partially controlled by available vaccines, and the virus retains the ability to replicate and spread between vaccinated birds. Following an initial infection, MDV enters a latent state and integrates into host telomeres and this may be a prerequisite for malignant transformation, which is usually fatal. To understand the mechanism that underlies the dynamic relationship between integrated-latent and reactivated MDV, we have characterized integrated MDV (iMDV) genomes and their associated telomeres. This revealed a single orientation among iMDV genomes and the loss of some terminal sequences that is consistent with integration by homology-directed recombination and excision via a telomere-loop-mediated process.
Sujet(s)
Poulets , Génome viral , Herpèsvirus aviaire de type 2 , Recombinaison homologue , Maladie de Marek , Télomère , Intégration virale , Animaux , Poulets/virologie , Génome viral/génétique , Herpèsvirus aviaire de type 2/génétique , Maladie de Marek/génétique , Maladie de Marek/virologie , Maladies de la volaille/génétique , Maladies de la volaille/virologie , Télomère/génétique , Vaccins antiviraux/immunologie , Activation virale , Latence virale , Intégration virale/génétiqueRÉSUMÉ
Marek's disease is a significant illness in chickens and a potential threat to the poultry industry worldwide. Marek's disease virus (MDV) causes immunosuppression and lymphoproliferative disease in chickens, but the turkey is an unusual host for the virus, and tumors caused by MDV in turkeys are unique. This study sampled 15 asymptomatic commercial turkey flocks (five spleens from each flock) at slaughter. Gallid alphaherpesvirus 2 (GaHV-2) was identified by PCR of spleen samples of two flocks. A phylogenetic analysis of the Meq gene was also performed. Sequencing and phylogenetic analysis revealed that the turkey GaHV-2 had genetic similarity with GaHV-2 strains recently detected in the Iranian commercial layer and breeder turkey flocks. This is the first time MDV has been detected in turkey flocks of Iran, and therefore, further assays including experimental inoculation to demonstrate pathotype characteristics in vivo are needed.
Nota de investigación- Virus de la enfermedad de Marek en parvadas comerciales de pavos en Irán. La enfermedad de Marek es una enfermedad importante de los pollos y una amenaza potencial para la industria avícola en todo el mundo. El virus de la enfermedad de Marek (MDV) causa inmunosupresión y una enfermedad linfoproliferativa en pollos, pero el pavo es un huésped inusual para este virus y los tumores causados por el virus de la enfermedad de Marek en pavos son únicos. En este estudio se recolectaron muestras de 15 lotes de pavos comerciales asintomáticos (cinco bazos de cada lote) en el momento del sacrificio. El Gallid alphaherpesvirus 2 (GaHV-2) fue identificado por PCR de muestras de bazo de dos parvadas. También se realizó un análisis filogenético del gene Meq. La secuenciación y el análisis filogenético revelaron que el GaHV-2 de pavo tenía una similitud genética con las cepas de GaHV-2 detectadas recientemente en parvadas de postura comerciales y de pavos reproductores iraníes. Esta es la primera vez que se detecta el virus de Marek en parvadas de pavos de Irán y, por lo tanto, se necesitan más ensayos, incluida la inoculación experimental, para demostrar las características del patotipo in vivo.
Sujet(s)
Herpèsvirus aviaire de type 2 , Maladie de Marek , Phylogenèse , Maladies de la volaille , Dindons , Animaux , Maladie de Marek/virologie , Maladie de Marek/épidémiologie , Iran/épidémiologie , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/isolement et purification , Herpèsvirus aviaire de type 2/classification , Maladies de la volaille/virologie , Maladies de la volaille/épidémiologieRÉSUMÉ
BACKGROUND: Duck plague virus (DPV), belonging to herpesviruses, is a linear double-stranded DNA virus. There are many reports about the outbreak of the duck plague in a variety of countries, which caused huge economic losses. Recently, increasing reports revealed that multiple long non-coding RNAs (lncRNAs) can possess great potential in the regulation of host antiviral immune response. Furthermore, it remains to be determined which specific molecular mechanisms are responsible for the DPV-host interaction in host immunity. Here, lncRNAs and mRNAs in DPV infected duck embryonic fibroblast (DEF) cells were identified by high-throughput RNA-sequencing (RNA-seq). And we predicted target genes of differentially expressed genes (DEGs) and formed a complex regulatory network depending on in-silico analysis and prediction. RESULT: RNA-seq analysis results showed that 2921 lncRNAs were found at 30 h post-infection (hpi). In our study, 218 DE lncRNAs and 2840 DE mRNAs were obtained in DEF after DPV infection. Among these DEGs and target genes, some have been authenticated as immune-related molecules, such as a Macrophage mannose receptor (MR), Anas platyrhynchos toll-like receptor 2 (TLR2), leukocyte differentiation antigen, interleukin family, and their related regulatory factors. Furthermore, according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analysis, we found that the target genes may have important effects on biological development, biosynthesis, signal transduction, cell biological regulation, and cell process. Also, we obtained, the potential targeting relationship existing in DEF cells between host lncRNAs and DPV-encoded miRNAs by software. CONCLUSIONS: This study revealed not only expression changes, but also the possible biological regulatory relationship of lncRNAs and mRNAs in DPV infected DEF cells. Together, these data and analyses provide additional insight into the role of lncRNAs and mRNAs in the host's immune response to DPV infection.
Sujet(s)
Canards/embryologie , Fibroblastes/virologie , Maladie de Marek/virologie , Maladies de la volaille/virologie , ARN long non codant/métabolisme , ARN messager/métabolisme , Animaux , Épidémies de maladies/médecine vétérinaire , Canards/génétique , Canards/virologie , Fibroblastes/métabolisme , Analyse de profil d'expression de gènes , Infections à Herpesviridae/métabolisme , Mardivirus , Maladie de Marek/épidémiologie , Maladie de Marek/immunologie , Maladies de la volaille/épidémiologie , Maladies de la volaille/immunologie , ARN long non codant/analyse , ARN long non codant/génétique , ARN messager/analyse , ARN messager/génétiqueRÉSUMÉ
Circular RNAs (circRNAs) are a recently rediscovered class of functional noncoding RNAs that are involved in gene regulation and cancer development. Next-generation sequencing approaches identified circRNA fragments and sequences underlying circularization events in virus-induced cancers. In the present study, we performed viral circRNA expression analysis and full-length sequencing in infections with Marek's disease virus (MDV), which serves as a model for herpesvirus-induced tumorigenesis. We established inverse PCRs to identify and characterize circRNA expression from the repeat regions of the MDV genome during viral replication, latency, and reactivation. We identified a large variety of viral circRNAs through precise mapping of full-length circular transcripts and detected matching sequences with several viral genes. Hot spots of circRNA expression included the transcriptional unit of the major viral oncogene encoding the Meq protein and the latency-associated transcripts (LATs). Moreover, we performed genome-wide bioinformatic analyses to extract back-splice junctions from lymphoma-derived samples. Using this strategy, we found that circRNAs were abundantly expressed in vivo from the same key virulence genes. Strikingly, the observed back-splice junctions do not follow a unique canonical pattern, compatible with the U2-dependent splicing machinery. Numerous noncanonical junctions were observed in viral circRNA sequences characterized from in vitro and in vivo infections. Given the importance of the genes involved in the transcription of these circRNAs, our study contributes to our understanding and complexity of this deadly pathogen. IMPORTANCE Circular RNAs (circRNAs) were rediscovered in recent years both in physiological and pathological contexts, such as in cancer. Viral circRNAs are encoded by at least two human herpesviruses, the Epstein Barr virus and the Kaposi's Sarcoma-associated herpesvirus, both associated with the development of lymphoma. Marek's disease virus (MDV) is a well-established animal model to study virus-induced lymphoma but circRNA expression has not been reported for MDV yet. Our study provided the first evidence of viral circRNAs that were expressed at key steps of the MDV lifecycle using genome-wide analyses of circRNAs. These circRNAs were primarily found in transcriptional units that corresponded to the major MDV virulence factors. In addition, we established a bioinformatics pipeline that offers a new tool to identify circular RNAs in other herpesviruses. This study on the circRNAs provided important insights into major MDV virulence genes and herpesviruses-mediated gene dysregulation.
Sujet(s)
Infections à virus Epstein-Barr , Herpèsvirus aviaire de type 2 , Maladie de Marek , ARN circulaire , Animaux , Poulets , Étude d'association pangénomique , Herpèsvirus aviaire de type 2/génétique , Herpèsvirus aviaire de type 2/pathogénicité , Lymphomes/virologie , Maladie de Marek/virologie , Protéines des oncogènes viraux/génétique , ARN circulaire/génétique , ARN non traduit/génétique , Virulence/génétiqueRÉSUMÉ
Marek's disease (MD) vaccines reduce the incidence of MD but cannot control virus shedding. To develop new vaccines, it is essential to elucidate mechanisms of immunity to Marek's disease virus (MDV) infection. In this regard, gamma delta (γδ) T cells may play a significant role in prevention of viral spread and tumor surveillance. Here we demonstrated that MDV vaccination induced interferon (IFN)-γ+CD8α+ γδ T cells and transforming growth factor (TGF)-ß+ γδ T cells in lungs. γδ T cells from MDV-infected chickens exhibited cytotoxic activity. Importantly, γδ T cells from the vaccinated/challenged group exhibited maximum cytotoxic activity following ex vivo stimulation. These results suggest that MDV vaccines activate effector γδ T cells which may be involved in the development of protective immune responses against MD. Further, it was demonstrated that MDV infection increases the frequency of a subpopulation of γδ T cells expressing membrane-bound TGF-ß in MDV-infected birds.
Sujet(s)
Poulets/immunologie , Maladie de Marek/immunologie , Récepteur lymphocytaire T antigène, gamma-delta/métabolisme , Sous-populations de lymphocytes T/immunologie , Sous-populations de lymphocytes T/métabolisme , Animaux , Marqueurs biologiques , Poulets/virologie , Cytokines , Séquençage nucléotidique à haut débit , Interactions hôte-pathogène/génétique , Interactions hôte-pathogène/immunologie , Immunisation , Immunophénotypage , Activation des lymphocytes , Numération des lymphocytes , Maladie de Marek/prévention et contrôle , Maladie de Marek/virologie , Maladies de la volaille/immunologie , Maladies de la volaille/prévention et contrôle , Maladies de la volaille/virologie , Vaccins antiviraux/immunologie , Réplication virale , Excrétion viraleRÉSUMÉ
BACKGROUND: Marek's disease (MD) is a lymphoproliferative disease caused by Gallid alphaherpesvirus 2 (GaHV-2, MDV-1), which primarily affects chickens. However, the virus is also able to induce tumors and polyneuritis in turkeys, albeit less frequently than in chickens. RESULTS: This is the first study in Turkey reporting the molecular characterization of a MDV-1 strain detected in a flock of backyard turkeys exhibiting visceral lymphoma. Here, MEQ, vIL-8, pp38 and 132-bp tandem repeat regions, which are frequently preferred in the pathotyping of MDV-1, were examined. It was determined that the MEQ gene of MDV-1/TR-21/turkey strain obtained in the present study encoded 339 amino acids (1020 nt) and had four proline-rich repeat regions (PPPP). Based on the nucleotide sequence of the MEQ gene of the MDV-1/TR-21/turkey strain, a phylogenetic tree was created using the MEGA-X software with the Maximum Likelihood Method (in 1000 replicates). Our strain was highly identical (> 99.8) to the Italian/Ck/625/16, Polish (Polen5) and some Turkish (Layer-GaHV-2-02-TR-2017, Tr/MDV-1/19) MDV-1 strains. Also, nt and aa sequences of the MEQ gene of our strain were 99.1 and 99.41% identical to another Turkish strain (MDV/Tur/2019) originated from chickens. Sequence analysis of pp38 and vIL-8 genes also supported the above finding. The identity ratios of nucleotide and amino acid sequences of vIL-8 and pp38 genes of MDV-1/TR-21/turkey strain were 99.64-100% and 99.79-100%, respectively, when compared with those of the Polish strain. According to 132-bp tandem repeat PCR results, the MDV-1/TR-21/turkey strain had five copies. CONCLUSIONS: These results suggested that the MDV-1/TR-21/turkey strain obtained from backyard turkeys can be either very virulent or very virulent plus pathotype, though experimental inoculation is required for precise pathotyping.
Sujet(s)
Herpèsvirus aviaire de type 2 , Maladie de Marek , Maladies de la volaille , Animaux , Herpèsvirus aviaire de type 2/génétique , Maladie de Marek/épidémiologie , Maladie de Marek/virologie , Phylogenèse , Maladies de la volaille/épidémiologie , Maladies de la volaille/virologie , Sérogroupe , Turquie , Dindons/virologieRÉSUMÉ
Vaccines against Marek's disease can protect chickens against clinical disease; however, infected chickens continue to propagate the Marek's disease virus (MDV) in feather follicles and can shed the virus into the environment. Therefore, the present study investigated if MDV could induce an immunoregulatory microenvironment in feathers of chickens and whether vaccines can overcome the immune evasive mechanisms of MDV. The results showed an abundance of CD4+CD25+ and CD4+ transforming growth factor-beta (TGF-ß)+ T regulatory cells in the feathers of MDV-infected chickens at 21 days post-infection. In contrast, vaccinated chickens had a lower number of regulatory T cells. Furthermore, the expression of TGF-ß and programmed cell death receptor (PD)-1 increased considerably in the feathers of Marek's disease virus-infected chickens. The results of the present study raise the possibility of an immunoregulatory environment in the feather pulp of MDV-infected chickens, which may in turn favor replication of infectious MDV in this tissue. Exploring the evasive strategies employed by MDV will facilitate the development of control measures to prevent viral replication and transmission.