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Journal of Virology Sep 2021During retroviral replication, unspliced viral genomic RNA (gRNA) must escape the nucleus for translation into viral proteins and packaging into virions. "Complex"...
During retroviral replication, unspliced viral genomic RNA (gRNA) must escape the nucleus for translation into viral proteins and packaging into virions. "Complex" retroviruses, such as human immunodeficiency virus (HIV), use -acting elements on the unspliced gRNA in conjunction with -acting viral proteins to facilitate this escape. "Simple" retroviruses, such as Mason-Pfizer monkey virus (MPMV) and murine leukemia virus (MLV), exclusively use -acting elements on the gRNA in conjunction with host nuclear export proteins for nuclear escape. Uniquely, the simple retrovirus Rous sarcoma virus (RSV) has a Gag structural protein that cycles through the nucleus prior to plasma membrane binding. This trafficking has been implicated in facilitating gRNA nuclear export and is thought to be a required mechanism. Previously described mutants that abolish nuclear cycling displayed enhanced plasma membrane binding, enhanced virion release, and a significant loss in genome incorporation resulting in loss of infectivity. Here, we describe a nuclear cycling-deficient RSV Gag mutant that has similar plasma membrane binding and genome incorporation to wild-type (WT) virus and surprisingly is replication competent, albeit with a slower rate of spread than observed in WT virus. This mutant suggests that RSV Gag nuclear cycling is not strictly required for RSV replication. While mechanisms for retroviral Gag assembly at the plasma membrane are beginning to be characterized, characterization of intermediate trafficking locales remain elusive. This is in part due to the difficulty of tracking individual proteins from translation to plasma membrane binding. Rous sarcoma virus (RSV) Gag nuclear cycling is a unique phenotype that may provide comparative insight to viral trafficking evolution and may present a model intermediate to - and -acting mechanisms for gRNA export.
Topics: Active Transport, Cell Nucleus; Animals; Cell Line; Cell Nucleus; Gene Products, gag; Genome, Viral; Humans; Mice; RNA, Viral; Retroviridae; Rous sarcoma virus; Virion; Virus Assembly
PubMed: 34319154
DOI: 10.1128/JVI.00648-21 -
Journal of Virology Jan 2022The CCCH-type zinc finger antiviral protein (ZAP) can recognize and induce the degradation of mRNAs and proteins of certain viruses, as well as exerting its antiviral...
The CCCH-type zinc finger antiviral protein (ZAP) can recognize and induce the degradation of mRNAs and proteins of certain viruses, as well as exerting its antiviral activity by activating T cells. However, the mechanism of ZAP that mediates T cell activation during virus infection remains unclear. Here, we found a potential function of ZAP that relieves immunosuppression of T cell induced by avian leukosis virus subgroup J (ALV-J) via a novel signaling pathway that involves norbin-like protein (NLP), protein kinase C delta (PKC-δ), and nuclear factor of activated T cell (NFAT). Specifically, ZAP expression activated T cells by promoting the dephosphorylation and nuclear translocation of NFAT. Furthermore, knockdown of ZAP weakened the reactivity and antiviral response of T cells. Mechanistically, ZAP reduced PKC-δ activity by upregulating and reactivating NLP by competitively binding with viral protein. Knockdown of NLP decreased the dephosphorylation of PKC-δ by ZAP expression. Moreover, we show that knockdown of PKC-δ reduced the phosphorylation levels of NFAT and enhanced its nuclear translocation. Taken together, these data revealed that ZAP relieves immunosuppression caused by ALV-J and mediates T cell activation through the NLP-PKC-δ-NFAT pathway. The evolution of the host defense system is driven synchronously in the process of resisting virus invasion. Accordingly, host innate defense factors effectively work to suppress virus replication. However, it remains unclear whether the host innate defense factors are involved in antiviral immune responses against the invasion of immunosuppressive viruses. Here, we found that CCCH-type zinc finger antiviral protein (ZAP) effectively worked in resistance to immunosuppression caused by avian leukosis virus subgroup J (ALV-J), a classic immunosuppressive virus. Evidence showed that ZAP released the phosphatase activity of NLP inhibited by ALV-J and further activated NFAT by inactivating PKC-δ. This novel molecular mechanism, i.e., ZAP regulation of the antiviral immune response by mediating the NLP-PKC-δ-NFAT pathway, has greatly enriched the understanding of the functions of host innate defense factors and provided important scientific ideas and a theoretical basis for research on immunosuppressive viruses and antiviral immunity.
Topics: Animals; Avian Leukosis Virus; Chickens; Host-Pathogen Interactions; Immune Tolerance; Lymphocyte Activation; NFATC Transcription Factors; Nerve Tissue Proteins; Phosphorylation; Protein Binding; Protein Kinase C-delta; RNA-Binding Proteins; Signal Transduction; T-Lymphocytes; Viral Proteins
PubMed: 34705559
DOI: 10.1128/JVI.01344-21 -
Virulence Dec 2021Avian leukosis virus subgroup J (ALV-J) generally induces hemangioma, myeloid leukosis, and immunosuppression in chickens, causing significant poultry industry economic...
Avian leukosis virus subgroup J (ALV-J) generally induces hemangioma, myeloid leukosis, and immunosuppression in chickens, causing significant poultry industry economic losses worldwide. The unusual gene of ALV-J, with low homology to other subgroups of ALVs, is associated with its unique pathogenesis. However, the exact molecular basis for the pathogenesis and oncogenesis of ALV-J is still not fully understood. In this study, ALV-J infection and the overexpression of Env could efficiently downregulate the phosphorylation of SHP-2 (pSHP-2) and . The membrane-spanning domain (MSD) in Env Gp37 was the functional domain responsible for pSHP-2 downregulation. Moreover, the overexpression of SHP-2 could effectively promote the replication of ALV-J, whereas knockout or allosteric inhibition of SHP-2 could inhibit ALV-J replication. In addition, the knockout of endogenous chicken SHP-2 could significantly increase the proliferation ability of DF-1 cells. All these data demonstrate that SHP-2 dephosphorylated by ALV-J Env could efficiently promote ALV-J replication, highlighting the important role of SHP-2 in the pathogenesis of ALV-J and providing a new target for developing antiviral drugs against ALV-J.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Chickens; Genes, env; Poultry Diseases; Protein Tyrosine Phosphatase, Non-Receptor Type 11; Virus Replication
PubMed: 34167452
DOI: 10.1080/21505594.2021.1939952 -
Scientific Reports Feb 2024Lymphoid leukosis is a poultry neoplastic disease caused by avian leukosis virus (ALV) and is characterized by high morbidity and variable mortality rates in chicks....
Lymphoid leukosis is a poultry neoplastic disease caused by avian leukosis virus (ALV) and is characterized by high morbidity and variable mortality rates in chicks. Currently, no effective treatment and vaccination is the only means to control it. This study exploited the immunoinformatics approaches to construct multi-epitope vaccine against ALV. ABCpred and IEDB servers were used to predict B and T lymphocytes epitopes from the viral proteins, respectively. Antigenicity, allergenicity and toxicity of the epitopes were assessed and used to construct the vaccine with suitable adjuvant and linkers. Secondary and tertiary structures of the vaccine were predicted, refined and validated. Structural errors, solubility, stability, immune simulation, dynamic simulation, docking and in silico cloning were also evaluated.The constructed vaccine was hydrophilic, antigenic and non-allergenic. Ramchandran plot showed most of the residues in the favored and additional allowed regions. ProsA server showed no errors in the vaccine structure. Immune simulation showed significant immunoglobulins and cytokines levels. Stability was enhanced by disulfide engineering and molecular dynamic simulation. Docking of the vaccine with chicken's TLR7 revealed competent binding energies.The vaccine was cloned in pET-30a(+) vector and efficiently expressed in Escherichia coli. This study provided a potent peptide vaccine that could assist in tailoring a rapid and cost-effective vaccine that helps to combat ALV. However, experimental validation is required to assess the vaccine efficiency.
Topics: Animals; Molecular Docking Simulation; Avian Leukosis Virus; Protein Subunit Vaccines; Immunoinformatics; Chickens; Epitopes, T-Lymphocyte; Molecular Dynamics Simulation; Epitopes, B-Lymphocyte; Vaccines, Subunit; Computational Biology
PubMed: 38311642
DOI: 10.1038/s41598-024-53048-6 -
Journal of Virology Feb 2022Glycans on envelope glycoprotein (Env) of the subgroup J avian leukosis virus (ALV-J) play an essential role in the virion integrity and infection process. In this...
Glycans on envelope glycoprotein (Env) of the subgroup J avian leukosis virus (ALV-J) play an essential role in the virion integrity and infection process. In this study, we found that, among the 13 predicted N-linked glycosylation sites (NGSs) in of Tibetan chicken strain TBC-J6, N17, and N193/N191 are pivotal for virus replication. Further research illustrated that a mutation at N193 weakened Env-receptor binding in a blocking assay of the viral entrance, coimmunoprecipitation, and ELISA. Our studies also showed that N17 was involved in Env protein processing and later virion incorporation based on the detection of p27 and Env protein in the supernatant and in the cell culture. This report is systematic research on clarifying the biological function of NGSs on ALV-J , which would provide valuable insight into the role of in the ALV life cycle and anti-ALV-J strategies. ALV-J is a retrovirus that can cause multiple types of tumors in chickens. Among all the viral proteins, the heavily glycosylated envelope protein is especially crucial. Glycosylation plays a major role in Env protein function, including protein processing, receptor attachment, and immune evasion. Notably, viruses isolated recently seem to lose their 6 and 11 NGS, which proved to be important in receptor binding. In our study, the 1 (N17) and 8 (N193) NGS of of the strain TBC-J6 can largely influence the titer of this virus. Deglycosylation at N193 weakened Env-receptor binding while mutation at N17 influenced Env protein processing. This study systemically analyzed the function of NGSs in ALV-J in different aspects, which may help us to understand the life cycle of ALV-J and provide antiviral targets for the control of ALV-J.
Topics: Animals; Avian Leukosis Virus; Cell Line; Chickens; Glycosylation; Mutation; Protein Binding; Protein Processing, Post-Translational; Receptors, Virus; Viral Envelope Proteins; Viral Load; Virion
PubMed: 34878920
DOI: 10.1128/JVI.01549-21 -
Poultry Science Nov 2021As important immunosuppressive viruses, chicken infectious anemia virus (CIAV) and subgroup J avian leukosis virus (ALV-J) have caused huge economic losses to the...
As important immunosuppressive viruses, chicken infectious anemia virus (CIAV) and subgroup J avian leukosis virus (ALV-J) have caused huge economic losses to the poultry industry globally. Recently, the co-infection of CIAV and ALV-J frequently occurred in the domestic chicken flocks in China. However, the synergistic pathogenesis of CIAV and ALV-J has not been fully investigated. Here, a co-infection study was performed to further understand the potential synergistic pathogenesis of CIAV and ALV-J. In vitro study showed that CIAV could promote the replication of ALV-J in HD11 cells, but ALV-J could not increase the replication of CIAV. Chicken infection study showed both CIAV and ALV-J with synergistic effects caused significant body weight loss to the infected chickens. Although ALV-J had no effect on CIAV viral shedding and tissue load, CIAV did significantly increase ALV-J viremia, viral shedding and tissue load in the co-infection group. Moreover, both CIAV and ALV-J could significantly inhibit the humoral immunity to H9N2 influenza virus and serotype 4 fowl adenovirus (FAdV-4). All these data demonstrate the synergistic pathogenesis for the co-infection of CIAV and ALV-J, and highlight the positive effect of CIAV on the pathogenesis of ALV-J.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Chicken anemia virus; Chickens; Influenza A Virus, H9N2 Subtype; Poultry Diseases
PubMed: 34624772
DOI: 10.1016/j.psj.2021.101468 -
Viruses Feb 2022A modified SELEX (Systematic Evolution of Ligands by Exponential Enrichment) pr,otocol (referred to as PT SELEX) was used to select primer-template (P/T) sequences that...
A modified SELEX (Systematic Evolution of Ligands by Exponential Enrichment) pr,otocol (referred to as PT SELEX) was used to select primer-template (P/T) sequences that bound to the vaccinia virus polymerase catalytic subunit (E9) with enhanced affinity. A single selected P/T sequence (referred to as E9-R5-12) bound in physiological salt conditions with an apparent equilibrium dissociation constant (K) of 93 ± 7 nM. The dissociation rate constant () and binding half-life (t) for E9-R5-12 were 0.083 ± 0.019 min and 8.6 ± 2.0 min, respectively. The values indicated a several-fold greater binding ability compared to controls, which bound too weakly to be accurately measured under the conditions employed. Loop-back DNA constructs with 3'-recessed termini derived from E9-R5-12 also showed enhanced binding when the hybrid region was 21 nucleotides or more. Although the sequence of E9-R5-12 matched perfectly over a 12-base-pair segment in the coding region of the virus B20 protein, there was no clear indication that this sequence plays any role in vaccinia virus biology, or a clear reason why it promotes stronger binding to E9. In addition to E9, five other polymerases (HIV-1, Moloney murine leukemia virus, and avian myeloblastosis virus reverse transcriptases (RTs), and and Klenow DNA polymerases) have demonstrated strong sequence binding preferences for P/Ts and, in those cases, there was biological or potential evolutionary relevance. For the HIV-1 RT, sequence preferences were used to aid crystallization and study viral inhibitors. The results suggest that several other DNA polymerases may have P/T sequence preferences that could potentially be exploited in various protocols.
Topics: Avian Myeloblastosis Virus; Base Sequence; DNA, Viral; DNA-Directed DNA Polymerase; HIV Reverse Transcriptase; Moloney murine leukemia virus; Protein Binding; SELEX Aptamer Technique; Vaccinia virus; Viral Proteins; Virus Replication
PubMed: 35215961
DOI: 10.3390/v14020369 -
BMC Veterinary Research Jun 2020Studies have shown that some viral infections cause structural changes in the intestinal microflora, but little is known about the effects of tumorigenic viral infection...
BACKGROUND
Studies have shown that some viral infections cause structural changes in the intestinal microflora, but little is known about the effects of tumorigenic viral infection on the intestinal microflora of chickens.
RESULTS
A 29-week commercial layer flock positive for avian leukosis virus-J (ALV-J), Marek's disease virus (MDV) and avian reticuloendotheliosis virus (REV) was selected, and fresh fecal samples were collected and examined for the composition of the gut microflora by Illumina sequencing of the V3-V4 region of the 16S rRNA gene. The operational taxonomic units (OTUs) of the fecal microbiota differentiated the chickens infected with only ALV-J and those coinfected with ALV-J and MDV or REV from infection-negative chickens. The enrichment and diversity of cloacal microflora in chickens infected with ALV-J alone were slightly different from those in the infection-negative chickens. However, the diversity of cloacal microflora was significantly increased in chickens coinfected with both ALV-J and MDV or REV.
CONCLUSIONS
The intestinal microbiota was more strongly disturbed in chickens after coinfection with ALV-J and MDV or REV than after infection with ALV-J alone, and there may be underlying mechanisms by which the capacity for the stabilization of the intestinal flora was impaired due to viral infection and tumorigenesis.
Topics: Animals; Avian Leukosis; Avian Leukosis Virus; Bacteria; Chickens; Coinfection; Feces; Female; Gastrointestinal Microbiome; Herpesvirus 2, Gallid; Marek Disease; Poultry Diseases; RNA, Ribosomal, 16S; Reticuloendotheliosis virus; Retroviridae Infections; Tumor Virus Infections
PubMed: 32600312
DOI: 10.1186/s12917-020-02430-3 -
Virology Journal Feb 2018In spite of the purification of the laying hens and broilers of avian leukosis virus (ALV) has made remarkable achievements, the infection of ALV was still serious in...
BACKGROUND
In spite of the purification of the laying hens and broilers of avian leukosis virus (ALV) has made remarkable achievements, the infection of ALV was still serious in Chinese indigenous chickens.
METHODS
In order to assess the epidemic state of avian leukosis virus in indigenous chickens in China, 10 novel strains of ALV subgroup J (ALV-J), named JS16JH01 to JS16JH10, were isolated and identified by virus isolation and immunofluorescence antibody assays from a Chinese local breed farm with a sporadic incidence of tumors. To understand their virological characteristics further, the proviral genome of ENV-LTR was sequenced and compared with the reference strains.
RESULTS
The homology of the gp85 gene between the ten ALV-J strains and NX0101 was in the range from 89.7-94.8% at the nuclear acid level. In addition, their gp85 genes were quite varied, with identities of 92-98% with themselves at the nuclear acid level. There were several snp and indel sites in the amino acid sequence of gp85 genes after comparison with other reference strains of ALV. Interestingly, a novel insertion in the gp85 region was found in two strains, JS16JH01 and JS16JH07, compared with NX0101 and HPRS-103.
DISCUSSION
At present, owing to the large-scale purification of ALV in China, laying hens and broiler chickens with ALV infection are rarely detected, but ALVs are still frequently detected in the local chickens, which suggests that more efforts should be applied to the purification of ALV from indigenous chickens.
Topics: Amino Acid Sequence; Animals; Avian Leukosis; Avian Leukosis Virus; Chickens; China; Mutation; Phylogeny; Poultry Diseases; Terminal Repeat Sequences; Viral Envelope Proteins
PubMed: 29433551
DOI: 10.1186/s12985-018-0947-1 -
Poultry Science May 2018In poultry, fowl adenovirus (FAdV) and immunosuppressive virus co-infection is likely to cause decreased egg production, inclusion body hepatitis, and pericardial...
In poultry, fowl adenovirus (FAdV) and immunosuppressive virus co-infection is likely to cause decreased egg production, inclusion body hepatitis, and pericardial effusion syndrome. In this study, fowl adenovirus infection was found in parental and descendent generations of chickens. We used quantitative polymerase chain reaction (PCR) and dot blot hybridization to detect the infection of reticuloendotheliosis (REV), avian leukosis virus (ALV), and chicken infectious anemia virus (CIAV) in 480 plasma samples. The test samples were 34.58% FADV-positive, 22.29% REV-positive, 7.5% CAV-positive, and 0.63% ALV-positive. Sequence analysis showed that FADV belonged to serotype 7, which can cause inclusion body hepatitis. The ALV strain was ALV-A, in which the homology of gp85 gene and SDAU09C1 was 97.3%. The positive rate was lower because of the purification of avian leukemia, whereas the phylogenetic tree analysis of REV showed that the highest homology was with IBD-C1605, which was derived from a vaccine isolate. Through pathogen detection in poultry we present, to our knowledge, the first discovery of fowl adenovirus type 7 infection in parental chickens and found that there was co-infection of FAdV and several immunosuppressive viruses, such as the purified ALV and CIAV. This indicates that multiple infection of different viruses is ever-present, and more attention should be given in the diagnosis process.
Topics: Adenoviridae Infections; Animals; Avian Leukosis; Avian Leukosis Virus; Chicken anemia virus; Chickens; Circoviridae Infections; Coinfection; Female; Fowl adenovirus A; Phylogeny; Poultry Diseases; Reticuloendotheliosis virus; Retroviridae Infections; Tumor Virus Infections
PubMed: 29509913
DOI: 10.3382/ps/pex414