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Veterinary Research Sep 2021Congenital avian leukosis virus subgroup J (ALV-J) infection can induce persistent immunotolerance in chicken, however, the underlying mechanism remains unclear. Here,...
Congenital avian leukosis virus subgroup J (ALV-J) infection can induce persistent immunotolerance in chicken, however, the underlying mechanism remains unclear. Here, we demonstrate that congenital ALV-J infection induces the production of high-frequency and activated CD4CD25 Tregs that maintain persistent immunotolerance. A model of congenital infection by ALV-J was established in fertilized eggs, and hatched chicks showed persistent immunotolerance characterized by persistent viremia, immune organ dysplasia, severe imbalance of the ratio of CD4/CD8 T cells in blood and immune organs, and significant decrease in CD3 T cells and Bu-1 B cells in the spleen. Concurrently, the mRNA levels of IL-2, IL-10, and IFN-γ showed significant fluctuations in immune organs. Moreover, the frequency of CD4CD25 Tregs in blood and immune organs significantly increased, and the frequency of CD4CD25 Tregs was positively correlated with changes in ALV-J load in immune organs. Interestingly, CD4CD25 Tregs increased in the marginal zone of splenic nodules in ALV-J-infected chickens and dispersed to the germinal center. In addition, the proliferation and activation of B cells in splenic nodules was inhibited, and the number of IgM and IgG cells in the marginal zone significantly decreased. We further found that the mRNA levels of TGF- β and CTLA-4 in CD4CD25 Tregs of ALV-J-infected chickens significantly increased. Together, high-frequency and activated CD4CD25 Tregs inhibited B cells functions by expressing the inhibitory cytokine TGF-β and inhibitory surface receptor CTLA-4, thereby maintaining persistent immunotolerance in congenital ALV-J-infected chickens.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; CD4-Positive T-Lymphocytes; Chick Embryo; Chickens; Immune Tolerance; Poultry Diseases; Specific Pathogen-Free Organisms; T-Lymphocytes
PubMed: 34526112
DOI: 10.1186/s13567-021-00989-9 -
Poultry Science May 2022Avian leukosis virus (ALV) induces multiple tumors in chicken and is still prevalent in a lot of local flocks in China. In this study, we analyzed the ALV infection...
Avian leukosis virus (ALV) induces multiple tumors in chicken and is still prevalent in a lot of local flocks in China. In this study, we analyzed the ALV infection status in an Anyi tile-like gray chicken flock by DF1-cells isolation, virus identification, and genome sequencing. Results showed a 29% (29/100) ALV positive rate in this flock. Homology analysis based on env genes illustrated that all these stains belong to subgroup J (92-100% identities) and can be further divided into 5 batches, suggesting a higher diversity of ALV-J within the same flock. The whole-genome analysis of representative stains from each batch confirmed the close relationship between these isolated strains with previously reported strains from different regions (Guangxi, Shandong, and Heilongjiang), revealing the enrichment of different strains in Anyi tile-like grey chickens. This study provides the epidemiological data of ALV-J in a special chicken flock and a reference for the further eradication of ALV in China.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Chickens; China; Poultry Diseases
PubMed: 35381497
DOI: 10.1016/j.psj.2022.101764 -
Journal of Virology Dec 2019In 2010, sporadic cases of avian leukosis virus (ALV)-like bursal lymphoma, also known as spontaneous lymphoid leukosis (LL)-like tumors, were identified in two...
Endogenous Avian Leukosis Virus in Combination with Serotype 2 Marek's Disease Virus Significantly Boosted the Incidence of Lymphoid Leukosis-Like Bursal Lymphomas in Susceptible Chickens.
In 2010, sporadic cases of avian leukosis virus (ALV)-like bursal lymphoma, also known as spontaneous lymphoid leukosis (LL)-like tumors, were identified in two commercial broiler breeder flocks in the absence of exogenous ALV infection. Two individual ALV subgroup E (ALV-E) field strains, designated AF227 and AF229, were isolated from two different breeder farms. The role of these ALV-E field isolates in development of and the potential joint impact in conjunction with a Marek's disease virus (MDV) vaccine (SB-1) were further characterized in chickens of an experimental line and commercial broiler breeders. The experimental line 0.TVB*S1, commonly known as the rapid feathering-susceptible (RFS) line, of chickens lacks all endogenous ALV and is fully susceptible to all subgroups of ALV, including ALV-E. Spontaneous LL-like tumors occurred following infection with AF227, AF229, and a reference ALV-E strain, RAV60, in RFS chickens. Vaccination with serotype 2 MDV, SB-1, in addition to AF227 or AF229 inoculation, significantly enhanced the spontaneous LL-like tumor incidence in the RFS chickens. The spontaneous LL-like tumor incidence jumped from 14% by AF227 alone to 42 to 43% by AF227 in combination with SB-1 in the RFS chickens under controlled conditions. RNA-sequencing analysis of the LL-like lymphomas and nonmalignant bursa tissues of the RFS line of birds identified hundreds of differentially expressed genes that are reportedly involved in key biological processes and pathways, including signaling and signal transduction pathways. The data from this study suggested that both ALV-E and MDV-2 play an important role in enhancement of the spontaneous LL-like tumors in susceptible chickens. The underlying mechanism may be complex and involved in many chicken genes and pathways, including signal transduction pathways and immune system processes, in addition to reported viral genes. Lymphoid leukosis (LL)-like lymphoma is a low-incidence yet costly and poorly understood disease of domestic chickens. The observed unique characteristics of LL-like lymphomas are that the incidence of the disease is chicken line dependent; pathologically, it appeared to mimic avian leukosis but is free of exogenous ALV infection; inoculation of the nonpathogenic ALV-E or MDV-2 (SB-1) boosts the incidence of the disease; and inoculation of both the nonpathogenic ALV-E and SB-1 escalates it to much higher levels. This study was designed to test the impact of two new ALV-E isolates, recently derived from commercial broiler breeder flocks, in combination with the nonpathogenic SB-1 on LL-like lymphoma incidences in both an experimental egg layer line of chickens and a commercial broiler breeder line of chickens under a controlled condition. Data from this study provided an additional piece of experimental evidence on the potency of nonpathogenic ALV-E, MDV-2, and ALV-E plus MDV-2 in boosting the incidence of LL-like lymphomas in susceptible chickens. This study also generated the first piece of genomic evidence that suggests host transcriptomic variation plays an important role in modulating LL-like lymphoma formation.
Topics: Amino Acid Sequence; Animals; Avian Leukosis; Avian Leukosis Virus; Chickens; Coinfection; Disease Susceptibility; Gene Expression Regulation, Viral; Genotype; Herpesvirus 3, Gallid; Incidence; Lymphoma; Marek Disease; Marek Disease Vaccines; Poultry Diseases; Sequence Analysis, DNA; Signal Transduction; Transcriptome; Vaccination; Viral Vaccines
PubMed: 31554689
DOI: 10.1128/JVI.00861-19 -
Veterinary Research Mar 2019Avian leukosis virus subgroup J (ALV-J) infection can cause tumors and immunosuppression in infected chickens. Macrophages play a central role in host defense against...
Avian leukosis virus subgroup J (ALV-J) infection can cause tumors and immunosuppression in infected chickens. Macrophages play a central role in host defense against invading pathogens. In this study, we discovered an interesting phenomenon: ALV-J replication is weakened from 3 hours post-infection (hpi) to 36 hpi, which was verified using Western blotting and RT-PCR. To further investigate the interaction between ALV-J and macrophages, transcriptome analysis was performed to analyze the host genes' function in chicken primary monocyte-derived macrophages (MDM). Compared to the uninfected control, 624 up-regulated differentially expressed genes (DEG) and 341 down-regulated DEG at 3 hpi, and 174 up-regulated DEG and 87 down-regulated DEG at 36 hpi were identified in chicken MDM, respectively. ALV-J infection induced strong innate immune responses in chicken MDM at 3 hpi, instead of 36 hpi, according to the analysis results of Gene Ontology and KEGG pathway. Importantly, the host factors, such as up-regulated MIP-3α, IL-1β, iNOS, K60, IRG1, CH25H, NFKBIZ, lysozyme and OASL were involved in the host defense response during the course of ALV-J infection. On the contrary, up-regulated EX-FABP, IL4I1, COX-2, NFKBIA, TNFAIP3 and the Jak STAT pathway inhibitors including CISH, SOCS1 and SOCS3 are beneficial to ALV-J survival in chicken macrophages. We speculated that ALV-J tropism for macrophages helps to establish a latent infection in chicken MDM from 6 to 36 hpi. The present study provides a comprehensive view of the interactions between macrophages and ALV-J. It suggests the mechanisms of defense of chicken macrophages against ALV-J invasion and how ALV-J escape the host innate immune responses.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Blotting, Western; Chickens; Female; Gene Expression Profiling; Gene Expression Regulation; Macrophages; Male; Real-Time Polymerase Chain Reaction; Sequence Analysis, DNA; Virus Replication
PubMed: 30841905
DOI: 10.1186/s13567-019-0638-y -
MBio Feb 2022Accumulating evidence suggests that p53 is involved in viral infection. However, it remains elusive whether avian p53 orchestrates avian leukosis virus (ALV)...
Accumulating evidence suggests that p53 is involved in viral infection. However, it remains elusive whether avian p53 orchestrates avian leukosis virus (ALV) replication. We showed that p53 recruits the histone deacetylase 1 and 2 (HDAC1/2) complex to the ALV promoter to shut off ALV's promoter activity and viral replication. HDAC1/2 binding to the ALV promoter was abolished in the absence of p53. Moreover, we collected samples in ALV-infected chickens and found that the acetylation status of ALV-bound H3 and H4 histones correlated with ALV viremia. HDAC inhibitors (HDACi) potently increase ALV replication, but HDACi-promoted viral replication is dramatically reduced in cells with p53 depletion. These data demonstrate that p53 is critical for inhibition ALV replication and suggest that future studies of ALV replication need to account for the potential effects of p53 activity. Rous sarcoma virus (RSV)/ALV was the first retrovirus to be discovered, which was really the first hint that cancer, or a tumor, could be transmitted by a virus. The specific mechanisms that regulate ALV replication during infection remain poorly understood. Here, we show that avian p53 and HDAC complex inhibit ALV promoter activity and replication, and p53 inhibits ALV replication through binding to the ALV promoter. We demonstrated that the acetylation status of ALV-bound H3 and H4 histones correlates with ALV viremia level using clinical samples collected from commercial poultry. These findings identify both p53-mediated inhibition on ALV replication and a potential role for virus-induced tumorigenesis.
Topics: Animals; Chickens; Avian Leukosis Virus; Tumor Suppressor Protein p53; Antiviral Agents; Viremia; Histones; Neoplasms; Carcinogenesis; Poultry Diseases
PubMed: 35038897
DOI: 10.1128/mbio.03287-21 -
Virology Journal Apr 2015Subgroup A, B, and J ALVs are the most prevalent avian leukosis virus (ALV). Our study attempted to develop two SYBR Green I-based real-time PCR (RT-PCR) assays for...
Development and application of SYBR Green I real-time PCR assay for the separate detection of subgroup J Avian leukosis virus and multiplex detection of avian leukosis virus subgroups A and B.
BACKGROUND
Subgroup A, B, and J ALVs are the most prevalent avian leukosis virus (ALV). Our study attempted to develop two SYBR Green I-based real-time PCR (RT-PCR) assays for specific detection of ALV subgroup J (ALV-J) and multiplex detection of ALV subgroups A and B (ALV-A/B), respectively.
RESULTS
The two assays showed high specificity for ALV-J and ALV-A/B and the sensitivity of the two assays was at least 100 times higher than that of the routine PCR assay. The minimum virus detection limit of virus culture, routine PCR and real-time PCR for detection of ALV-A strain was 10(3) TCID50 units, 10(2) TCID50 units and fewer than 10 TCID50 units, respectively. In addition, the coefficients of variation for intra- and inter-assay were both less than 5%. Forty clinical plasma samples were evaluated by real-time PCR, routine PCR, and virus culture with positive rates of 80% (32/40), 72.5% (29/40) and 62.5% (25/40), respectively. When the assay for detection of ALV-J was used to quantify the viral load of various organ tissues in chicken inoculated by ALV-J strains CHN06 and NX0101, the results exhibited that ALV-J genes could be detected in all organ tissues examined and the highest copies of ALV-J were mainly in heart and kidney samples at 30 weeks post-infection. Except in lung, the virus copies of CHN06 group were higher than that of NX0101 group in various organ tissues.
CONCLUSIONS
The SYBR Green I-based real-time RT-PCR assay provides a powerful tool for the detection of ALV and study of virus replication and infection.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Benzothiazoles; Chickens; Diamines; Genes, Viral; Multiplex Polymerase Chain Reaction; Organic Chemicals; Quinolines; Real-Time Polymerase Chain Reaction; Reference Standards; Reproducibility of Results; Sensitivity and Specificity; Viral Load
PubMed: 25889925
DOI: 10.1186/s12985-015-0291-7 -
Viruses Sep 2021Wnt/β-catenin signaling is a highly conserved pathway related to a variety of biological processes in different cells. The regulation of replication of various viruses...
Wnt/β-catenin signaling is a highly conserved pathway related to a variety of biological processes in different cells. The regulation of replication of various viruses by Wnt/β-catenin signaling pathway has been reported. However, the interaction between the Wnt/β-catenin pathway and avian leukosis virus is unknown. In the present study, we investigated the effect of modulating the Wnt/β-catenin pathway during avian leukosis virus subgroup J (ALV-J) infection. The activation of the Wnt/β-catenin pathway by GSK-3 inhibitor increased ALV-J mRNA, viral protein expression, and virus production in CEF cells. This increase was suppressed by iCRT14, one of the specific inhibitors of the Wnt/β-catenin signaling pathway. Moreover, treatment with iCRT14 reduced virus titer and viral gene expression significantly in CEF and LMH cells in a dose-dependent manner. Inhibition Wnt/β-catenin signaling pathway by knockdown of β-catenin reduced virus proliferation in CEF cells also. Collectively, these results suggested that the status of Wnt/β-catenin signaling pathway modulated ALV-J replication. These studies extend our understanding of the role of Wnt/β-catenin signaling pathway in ALV-J replication and make a new contribution to understanding the virus-host interactions of avian leukosis virus.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Cell Line; Chick Embryo; Chickens; China; Gene Expression; Gene Expression Regulation, Viral; Glycogen Synthase Kinase 3; Poultry Diseases; Pyridines; Pyrroles; RNA, Messenger; Thiazolidinediones; Virus Replication; Wnt Signaling Pathway
PubMed: 34696398
DOI: 10.3390/v13101968 -
Nature Feb 2016Integration of the reverse-transcribed viral DNA into the host genome is an essential step in the life cycle of retroviruses. Retrovirus integrase catalyses insertions...
Integration of the reverse-transcribed viral DNA into the host genome is an essential step in the life cycle of retroviruses. Retrovirus integrase catalyses insertions of both ends of the linear viral DNA into a host chromosome. Integrase from HIV-1 and closely related retroviruses share the three-domain organization, consisting of a catalytic core domain flanked by amino- and carboxy-terminal domains essential for the concerted integration reaction. Although structures of the tetrameric integrase-DNA complexes have been reported for integrase from prototype foamy virus featuring an additional DNA-binding domain and longer interdomain linkers, the architecture of a canonical three-domain integrase bound to DNA remained elusive. Here we report a crystal structure of the three-domain integrase from Rous sarcoma virus in complex with viral and target DNAs. The structure shows an octameric assembly of integrase, in which a pair of integrase dimers engage viral DNA ends for catalysis while another pair of non-catalytic integrase dimers bridge between the two viral DNA molecules and help capture target DNA. The individual domains of the eight integrase molecules play varying roles to hold the complex together, making an extensive network of protein-DNA and protein-protein contacts that show both conserved and distinct features compared with those observed for prototype foamy virus integrase. Our work highlights the diversity of retrovirus intasome assembly and provides insights into the mechanisms of integration by HIV-1 and related retroviruses.
Topics: Catalytic Domain; Crystallography, X-Ray; DNA, Viral; HIV-1; Integrases; Models, Molecular; Protein Binding; Protein Multimerization; Rous sarcoma virus; Spumavirus; Virus Integration
PubMed: 26887497
DOI: 10.1038/nature16950 -
Journal of Virology Apr 2017All retroviruses need to integrate a DNA copy of their genome into the host chromatin. Cellular proteins regulating and targeting lentiviral and gammaretroviral...
All retroviruses need to integrate a DNA copy of their genome into the host chromatin. Cellular proteins regulating and targeting lentiviral and gammaretroviral integration in infected cells have been discovered, but the factors that mediate alpharetroviral avian leukosis virus (ALV) integration are unknown. In this study, we have identified the FACT protein complex, which consists of SSRP1 and Spt16, as a principal cellular binding partner of ALV integrase (IN). Biochemical experiments with purified recombinant proteins show that SSRP1 and Spt16 are able to individually bind ALV IN, but only the FACT complex effectively stimulates ALV integration activity Likewise, in infected cells, the FACT complex promotes ALV integration activity, with proviral integration frequency varying directly with cellular expression levels of the FACT complex. An increase in 2-long-terminal-repeat (2-LTR) circles in the depleted FACT complex cell line indicates that this complex regulates the ALV life cycle at the level of integration. This regulation is shown to be specific to ALV, as disruption of the FACT complex did not inhibit either lentiviral or gammaretroviral integration in infected cells. The majority of human gene therapy approaches utilize HIV-1- or murine leukemia virus (MLV)-based vectors, which preferentially integrate near genes and regulatory regions; thus, insertional mutagenesis is a substantial risk. In contrast, ALV integrates more randomly throughout the genome, which decreases the risks of deleterious integration. Understanding how ALV integration is regulated could facilitate the development of ALV-based vectors for use in human gene therapy. Here we show that the FACT complex directly binds and regulates ALV integration efficiency and in infected cells.
Topics: Amino Acid Sequence; Animals; Avian Leukosis Virus; Cell Cycle Proteins; Chick Embryo; Conserved Sequence; DNA, Viral; DNA-Binding Proteins; HEK293 Cells; High Mobility Group Proteins; Humans; Integrases; Protein Binding; Protein Interaction Domains and Motifs; Transcription Factors; Transcriptional Elongation Factors; Virus Integration
PubMed: 28122976
DOI: 10.1128/JVI.00082-17 -
Frontiers in Bioscience (Elite Edition) Jun 2018We investigated the impact of haplotype of major histocompatibility complex (MHC)-B on the outcome of infection of Synthetic Dam Line (SDL) broiler strain with Rous...
We investigated the impact of haplotype of major histocompatibility complex (MHC)-B on the outcome of infection of Synthetic Dam Line (SDL) broiler strain with Rous Sarcoma Virus (RSV). Genomic analysis of MHC-B haplotypes, revealed a total of 12 known standard haplotypes that constituted to twenty-five different genotypes and one new haplotype of 217 bp size, designated B. The inoculation of RSV-A in SDL chicks resulted in the development of tumors of progressive or regressive phenotypes with varying tumor profile index (TPI). Haplotypes B, B and Bhad low TPI scores (1 or 2) with less mortality and were resistant to RSV-A tumor. The haplotypes B, B, B, Band Bhad significantly higher TPI scores (5 or 6), indicating a susceptibility to RSV-A. The genotype, B /B, had a mean TPI score of 3.67 ± 1.33, which was closer to the resistant haplotype. Sequence analysis of the new haplotype (B) revealed 99.5% similarity with B2 haplotype. Metastases was observed in 44% of chicks and comprised of mixed fibrosarcoma and myxosarcoma.
Topics: Animals; Chickens; Haplotypes; Major Histocompatibility Complex; Rous sarcoma virus; Sarcoma, Avian
PubMed: 29772523
DOI: 10.2741/E837