Avian Leukosis Virus Subgroup J Infection Research Articles

C2H2-type zinc-finger protein BCL11B suppresses avian Leukosis virus subgroup J replication by regulating apoptosis

Apoptosis plays a crucial role in host antiviral defense. The avian leukosis virus subgroup J (ALV-J), an avian oncogenic retrovirus, has been shown to suppress apoptosis while promoting its own replication. ALV-J induces myeloid tumors and hemangiomas in chickens resulting in significant economic losses for commercial layer and meat-type chicken production. B-cell lymphoma/leukemia 11B (Bcl11b) encodes a C2H2-type zinc finger protein—BCL11B, that exerts critical functions in cell proliferation, differentiation, and plays an essential role in the immune system. Previous study has been shown that Bcl11b is associated with ALV-J infection. In this study, we further investigated the pathological changes in ALV-J infected cells and examined the role and expression regulation of chicken Bcl11b. Our results demonstrate that Bcl11b, as an interferon-stimulated gene (ISG), encodes C2H2-type zinc finger protein BCL11B that promotes apoptosis to inhibit ALV-J infection. Additionally, gga-miR-1612 and gga-miR-6701-3p regulate apoptosis and are involved in ALV-J infection by targeting Bcl11b, thus revealing immune response strategies between the host and ALV-J. Although the underlying mechanisms require further validation, Bcl11b and its regulatory miRNAs are the first to demonstrate inhibition of ALV-J replication via apoptosis. BCL11B can a valuable target for treating diseases triggered by ALV-J infection.

Conservation and distribution of the DRACH motif for potential m6A sites in avian leukosis virus subgroup J.

N6-methyladenosine (m6A) methylation is an internal post-transcriptional modification that has been linked to viral multiplication and pathogenicity. To elucidate the conservation patterns of potential 5'-DRACH-3' motifs in avian leukosis virus subgroup J (ALV-J), 149 ALV-J strains (139 isolates from China; ALV-J prototype HPRS-103 from the UK; and 9 strains from the USA, Russia, India, and Pakistan) available in GenBank before December 2023 were retrieved. According to the prediction results of the SRAMP web-server, these ALV-J genomes contained potential DRACH motifs, with the total number ranging from 43 to 64, which were not determined based on the isolation region and time. Conservative analysis suggested that 37 motifs exhibited a conservation of >80%, including 17 motifs with a grading above "high confidence." Although these motifs were distributed in the U5 region of LTRs and major coding regions, they were enriched in the coding regions of p27, p68, p32, and gp85. The most common m6A-motif sequence of the DRACH motif in the ALV-J genome was GGACU. The RNA secondary structure of each conserved motif predicted by SRAMP and RNAstructure web-server was mainly of two types-A-U pair (21/37) and hairpin loop (16/37)-based on the core adenosine. Considering the systematic comparative analysis performed in this study, future thorough biochemical research is warranted to determine the role of m6A modification during the replication and infection of ALV-J. These conservation and distribution analysis of the DRACH motif for potential m6A sites in ALV-J would provide a foundation for the future intervention of ALV-J infection and m6A modification.

Metabolomics analysis of CEF cells infected with avian leukosis virus subgroup J based on UHPLC-QE-MS

Avian leukosis virus subgroup J (ALV-J) is a retrovirus that can cause immunosuppression and tumors in chicken. However, relative pathogenesis is still not clear. At present, metabolomics has shown great potential in the screening of tumor metabolic markers, prognostic evaluation, and drug target design. In this study, we utilize an untargeted metabolomics approach based on ultrahigh-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS) to analyze the metabolic changes in chicken embryo fibroblast (CEF) cells infected by ALV-J. We found that ALV-J infection significantly altered a wealth of metabolites compared with control group. Additionally, most of the differentially expressed metabolites belonged to lipid metabolism, purine nucleotide metabolism and amino acid metabolism. Among them, the proportion of lipid metabolites account for the highest proportion (around 31%). Results suggest that these changes may be conductive to the formation of virion, thereby promoting the replication of ALV-J. These data provided metabolic evidence and potential biomarkers for the cellular metabolic changes induced by ALV-J, and provided important insight for further understanding the replication needs and pathogenesis of ALV-J.

Transcriptome-wide N6-methyladenosine modification and microRNA jointly regulate the infection of avian leukosis virus subgroup J in vitro

N6-methyladenosine (m6A) methylation in transcripts has been suggested to influence tumorigenesis in liver tumors caused by the avian leukosis virus subgroup J (ALV-J). However, m6A modifications during ALV-J infection in vitro remain unclear. Herein, we performed m6A and RNA sequencing in ALV-J-infected chicken fibroblasts (DF-1). A total of 51 differentially expressed genes containing differentially methylated peaks were identified, which were markedly enriched in microRNAs (miRNAs) in cancer cells as well as apoptosis, mitophagy and autophagy, RNA degradation, and Hippo and MAPK signaling pathways. Correlation analysis indicated that YTHDC1 (m6A-reader gene) plays a key role in m6A modulation during ALV-J infection. The env gene of ALV-J harbored the strongest peak, and untranslated regions and long terminal repeats also contained peaks of different degrees. To the best of our knowledge, this is the first thorough analysis of m6A patterns in ALV-J-infected DF-1 cells. Combined with miRNA profiles, this study provides a useful basis for future research into the key pathways of ALV-J infection associated with m6A alteration.

PMAIP1 promotes J subgroup avian leukosis virus replication by regulating mitochondrial function

Avian leukosis virus Subgroup J (ALV-J) exhibits high morbidity and pathogenicity, affecting approximately 20% of poultry farms. It induces neoplastic diseases and immunosuppression. Phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1), a proapoptotic mitochondrial protein in the B-cell lymphoma-2 (Bcl-2) family, plays a role in apoptosis in cancer cells. However, the connection between the PMAIP1 gene and ALV-J pathogenicity remains unexplored. This study investigates the potential impact of the PMAIP1 gene on ALV-J replication and its regulatory mechanisms. Initially, we examined PMAIP1 expression using quantitative real-time PCR (qRT-PCR) in vitro and in vivo. Furthermore, we manipulated PMAIP1 expression in chicken fibroblast cells (DF-1) and assessed its effects on ALV-J infection through qRT-PCR, immunofluorescence assay (IFA), and western blotting (WB). Our findings reveal a significant down-regulation of PMAIP1 in the spleen, lung, and kidney, coupled with an up-regulation in the bursa and liver of ALV-J infected chickens compared to uninfected ones. Additionally, DF-1 cells infected with ALV-J displayed a notable up-regulation of PMAIP1 at 6, 12, 24, 48, 74, and 108 h. Over-expression of PMAIP1 enhanced ALV-J replication, interferon expression, and proinflammatory factors. Conversely, interference led to contrasting results. Furthermore, we observed that PMAIP1 promotes virus replication by modulating mitochondrial function. In conclusion, the PMAIP1 gene facilitates virus replication by regulating mitochondrial function, thereby enriching our understanding of mitochondria-related genes and their involvement in ALV-J infection, offering valuable insights for avian leukosis disease resistance strategies.

Whole-genome resequencing to explore genome‑wide single nucleotide polymorphisms and genes associated with avian leukosis virus subgroup J infection in chicken.

Avian leukosis virus subgroup J (ALV-J) is an oncogenic virus that causes serious economic loss in the poultry industry. Currently, no effective vaccine or drug is available against this virus. Therefore, it is imperative to explore and understand the molecular regulatory mechanisms underlying ALV-J infection. In this study, blood samples from 21 ALV-J-infected and 22 ALV-J-uninfected (DZ) chickens (JZ) were analyzed by whole-genome resequencing (WGR). By combining the fixation index (FST) with the nucleotide diversity (π) ratio based on WGR data, 425 candidate genes were identified. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed the top 20 enriched pathways, among which 9 pathways were significantly associated with diseases, including endometrial cancer, Chagas disease, PD-L1 expression and PD-1 checkpoint pathway in cancer, colorectal cancer, endocrine resistance, fluid shear stress, atherosclerosis, basal cell carcinoma, non-small cell lung cancer, and melanoma. Fourteen single nucleotide polymorphisms related to twelve genes showed a notable difference between DZ and JZ group chickens. The genes included COMMD3, PPP1CB, VEGFA, GTF2H1, NOTCH2, ITPR1, FGFR4, GNAS, NECTIN1, WNT2B, PPP1CC, and MRC2. These findings may provide a valuable foundation for further exploration of the pathogenesis of ALV-J in chickens.

Proteomic profiling of purified avian leukosis virus subgroup J particles

While the presence of host cell proteins in virions and their role in viral life cycles have been demonstrated in various viruses, such characteristics have remained largely unknown in avian leukosis virus (ALV). To investigate whether this is the case in ALV, we purified high-integrity and high-purity virions from the avian leukosis virus subgroup J (ALV-J) and subjected them to proteome analysis using nano LC-MS/MS. This analysis identified 53 cellular proteins that are incorporated into mature ALV-J virions, and we verified the reliability of the packaged cellular proteins through subtilisin digestion and immunoblot analysis. Functional annotation revealed the potential functions of these proteins in the viral life cycle and tumorigenesis. Overall, our findings have important implications for understanding the interaction between ALV-J and its host, and provide new insights into the cellular requirements that define ALV-J infection.

CCL4 participates in the reprogramming of glucose metabolism induced by ALV-J infection in chicken macrophages.

Interferon and chemokine-mediated immune responses are two general antiviral programs of the innate immune system in response to viral infections and have recently emerged as important players in systemic metabolism. This study found that the chemokine CCL4 is negatively regulated by glucose metabolism and avian leukosis virus subgroup J (ALV-J) infection in chicken macrophages. Low expression levels of CCL4 define this immune response to high glucose treatment or ALV-J infection. Moreover, the ALV-J envelope protein is responsible for CCL4 inhibition. We confirmed that CCL4 could inhibit glucose metabolism and ALV-J replication in chicken macrophages. The present study provides novel insights into the antiviral defense mechanism and metabolic regulation of the chemokine CCL4 in chicken macrophages.

Chicken CH25H inhibits ALV-J replication by promoting cellular autophagy.

Autophagy plays an important role in host antiviral defense. The avian leukosis virus subgroup J (ALV-J) has been shown to inhibit autophagy while promoting viral replication. The underlying autophagic mechanisms, however, are unknown. Cholesterol 25-hydroxylase (CH25H) is a conserved interferon-stimulated gene, which converts cholesterol to a soluble antiviral factor, 25-hydroxycholesterol (25HC). In this study, we further investigated the autophagic mechanism of CH25H resistance to ALV-J in chicken embryonic fibroblast cell lines (DF1). Our results found that overexpression of CH25H and treatment with 25HC promoted the autophagic markers microtubule-associated protein 1 light chain 3 II (LC3II) and autophagy-related gene 5(ATG5), while decreased autophagy substrate p62/SQSTM1 (p62) expression in ALV-J infection DF-1 cells. Induction of cellular autophagy also reduces the levels of ALV-J gp85 and p27. ALV-J infection, on the other hand, suppresses autophagic marker protein LC3II expression. These findings suggest that CH25H-induced autophagy is a host defense mechanism that aids in ALV-J replication inhibition. In particular, CH25H interacts with CHMP4B and inhibits ALV-J infection in DF-1 cells by promoting autophagy, revealing a novel mechanism by which CH25H inhibits ALV-J infection. Although the underlying mechanisms are not completely understood, CH25H and 25HC are the first to show inhibiting ALV-J infection via autophagy.

Transcriptome-Wide Dynamics of m6A Methylation in Tumor Livers Induced by ALV-J Infection in Chickens.

Avian Leukosis Virus Subgroup J (ALV-J) is a tumorigenic virus with high morbidity and rapid transmission. N6-methyladenosine (m6A) is a common epigenetic modification that may be closely related to the pathogenicity of ALV-J. Currently, there are no reports on whether m6A modification is related to ALV-J induced tumor formation. In this study, we used methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) to examine the differences in m6A methylation and gene expression in normal livers and ALV-J-induced tumor livers systematically, with functional enrichment and co-expression analysis. The results identified 6,541 m6A methylated peaks, mainly enriched in CDS, and more than 83% of the transcripts contained 1-2 m6A peaks. For RNA-seq, 1,896 and 1,757 differentially expressed mRNAs and lncRNAs were identified, respectively. Gene enrichment analysis indicated that they may be involved in biological processes and pathways such as immunology-related and apoptosis. Moreover, we identified 17 lncRNAs, commonly existing in differently expressed methylome and transcriptome. Through co-expression analysis, 126 differentially expressed lncRNAs, and 18 potentially m6A-related methyltransferases were finally identified and connected, suggesting that m6A modifications might affect gene expression of lncRNAs and play a role in ALV-J induced tumor formation. This study provides the first comprehensive description of the m6A expression profile in tumor livers induced by ALV-J infection in chickens, which provides a basis for studying the role of m6A modification in ALV-J induced tumorigenesis. This study provides clues for studying the epigenetic etiology and pathogenesis of ALV-J.

Chicken Peripheral Blood Mononuclear Cells Response to Avian Leukosis Virus Subgroup J Infection Assessed by Single-Cell RNA Sequencing.

Chicken peripheral blood mononuclear cells (PBMCs) exhibit wide-ranging cell types, but current understanding of their subclasses, immune cell classification, and function is limited and incomplete. Here we performed single-cell RNA sequencing (scRNA-seq) of PBMCs in Avian leukosis virus subgroup J (ALV-J) infected and control chickens at 21 days post infection (DPI) to determine chicken PBMCs subsets and their specific molecular and cellular characteristics. Eight cell populations and their potential marker genes were identified in PBMCs. T cell populations had the strongest response to (ALV-J) infection, based on the detection of the largest number of differentially expressed genes (DEGs), and could be further grouped into four subsets: activated CD4+ T cells, Th1-like cells, Th2-like cells, and cytotoxic CD8+ T cells. Furthermore, pseudotime analysis results suggested that chicken CD4+ T cells could potentially differentiate into Th1-like and Th2-like cells. Moreover, ALV-J infection activated CD4+ T cell was probably inclined to differentiate into Th1-like cells. Compared to the control PBMCs, ALV-J infection also had an obvious impact on PBMCs composition. B cells showed inconspicuous response and their numbers decreased in PBMCs from ALV-J infected chicken. Proportions of cytotoxic Th1-like cells and CD8+ T cells increased in the T cell population of PBMCs from ALV-J infected chicken, which were potentially key mitigating effectors against ALV-J infection. More importantly, our results provide a rich resource of gene expression profiles of chicken PBMCs subsets for a systems-level understanding of their function in homeostatic condition as well as in response to viral infection.

Interaction of p10/p27 with macrophage migration inhibitory factor promotes avian leukosis virus subgroup J infection

Avian leukosis virus subgroup J (ALV-J), an oncogenic retrovirus, induces myelocytoma and various other tumors in broilers and layers. Many recent studies have shown that ALV-J can hijack host molecules to facilitate infection. However, the molecular mechanisms of this process are not clear. Here, we aimed to elucidate the molecular mechanisms contributing to ALV-J infection. ALV-J hijacked MIF via p10 and p27 to facilitate ALV-J infection. ALV-J persistently activated MIF expression in DF-1 cells, and MIF significantly facilitated ALV-J internalization and replication, which demonstrated by MIF overexpression and knockdown experiments and treatment with the MIF antagonist ISO-1. Furthermore, we found that the two subunit proteins of Gag, p10 and p27, interacted with MIF in the cytoplasm, respectively. These results suggested that the p10 and p27 subunit in Gag protein recruited MIF to promote ALV-J infection, providing insights into the roles of the p10/p27 and the host factor MIF in ALV-J infection. The finding may facilitate the development of new strategies for controlling ALV-J or retrovirus infections.

DPRLR causes differences in immune responses between early and late feathering chickens after ALV-J infection

To understand the differences in immune responses between early feathering (EF) and late feathering (LF) chickens after infection with avian leukosis virus, subgroup J (ALV-J), we monitored the levels of prolactin, growth hormone and the immunoglobulins IgG and IgM in the serum of LF and EF chickens for 8 weeks. Moreover, we analysed the expression of immune-related genes in the spleen and the expression of PRLR, SPEF2 and dPRLR in the immune organs and DF-1 cells by qRT–PCR. The results showed that ALV-J infection affected the expression of prolactin, growth hormone, IgG and IgM in the serum. Regardless of whether LF and EF chickens were infected with ALV-J, the serum levels of the two hormones and two immunoglobulins in EF chickens were higher than those in LF chickens (P < 0.05). However, the expression of immune-related genes in the spleen of positive LF chickens was higher than that in the spleen of positive EF chickens. In the four immune organs, PRLR and SPEF2 expression was also higher in LF chickens than in EF chickens. Furthermore, the dPRLR expression of positive LF chickens was higher than that of negative LF chickens. After infection with ALV-J, the expression of PRLR in DF-1 cells significantly increased. In addition, overexpression of PRLR or dPRLR in DF-1 cells promoted replication of ALV-J. These results suggested that the susceptibility of LF chickens to ALV-J might be induced by dPRLR.

Avian leukosis virus subgroup J infection influences the gut microbiota composition in Huiyang bearded chickens.

Avian leukosis virus (ALV) poses a major threat to poultry. The chicken gut microbiota plays critical roles in host performance, health and immunity. However, the effect of viral infection on the microbiota of Chinese local chickens is not well understood. In this study, we performed high-throughput 16S rRNA gene sequencing and evaluated the gut microbiota profiles using faeces from ALV subgroup J (ALV-J)-infected and healthy Huiyang bearded chickens (Chinese local chickens). At the phylum level, ALV-J infection mainly increased the abundance of Bacteroidetes and Proteobacteria and decreased that of Firmicutes. An analysis at the order, family and genus levels showed that the abundance of Lactobacillales, Lactobacillaceae and Lactobacillus was the highest in normal chicken faeces, accounting for 89·07%, 86·47% and 86·46%, respectively, of phylotypes. Moreover, samples from ALV-J-infected chickens were enriched with Bacteroidales, Clostridiales, Bacteroidaceae, Ruminococcaceae, Lachnospiraceae and Bacteroides. Our findings highlight that ALV-J infection alters the gut microbiota and disrupts the host-microbial homeostasis in chickens, which may be involved in the pathogenesis of ALV-J infection.

An Endogenous Retroviral LTR-Derived Long Noncoding RNA lnc-LTR5B Interacts With BiP to Modulate ALV-J Replication in Chicken Cells.

Infection with the avian leukosis virus subgroup J (ALV-J) impairs host genes and facilitates the establishment of chronic infection and the viral life cycle. However, the involvement of long noncoding RNAs (lncRNAs) in ALV-J infection remains largely unknown. In this study, we identified a novel chicken lncRNA derived from LTR5B of the ERV-L family (namely lnc-LTR5B), which is significantly downregulated in ALV-J infected cells. lnc-LTR5B was localized in the cytoplasm and was relatively high expressed in the chicken lung and liver. Notably, the replication of ALV-J was inhibited by the overexpression of lnc-LTR5B but enhanced when lnc-LTR5B expression was knocked down. We further confirmed that lnc-LTR5B could bind to the binding immunoglobulin protein (BiP), a master regulator of endoplasmic reticulum (ER) function. Mechanistically, lnc-LTR5B serves as a competing endogenous RNA for BiP, restricting its physical availability. Upon ALV-J infection, the reduction of lnc-LTR5B released BiP, which facilitated its translocation to the cell surface. This is crucial for ALV-J entry as well as pro-survival signaling. In conclusion, we identified an endogenous retroviral LTR-activated lnc-LTR5B that is involved in regulating the cell surface translocation of BiP, and such regulatory machinery can be exploited by ALV-J to complete its life cycle and propagate.

The Transcriptional Differences of Avian CD4+CD8+ Double-Positive T Cells and CD8+ T Cells From Peripheral Blood of ALV-J Infected Chickens Revealed by Smart-Seq2.

It is well known that chicken CD8+ T cell response is vital to clearing viral infections. However, the differences between T cell subsets expressing CD8 receptors in chicken peripheral blood mononuclear cells (PBMCs) have not been compared. Herein, we used Smart-Seq2 scRNA-seq technology to characterize the difference of chicken CD8high+, CD8high αα+, CD8high αβ+, CD8medium+, and CD4+CD8low+ T cell subsets from PBMCs of avian leukosis virus subgroup J (ALV-J)-infected chickens. Weighted gene co-expression network analysis (WGCNA) and Trend analysis revealed that genes enriched in the “Cytokine–cytokine receptor interaction” pathway were most highly expressed in the CD8high αα+ T cell population, especially T cell activation or response-related genes including CD40LG, IL2RA, IL2RB, IL17A, IL1R1, TNFRSF25, and TNFRSF11, suggesting that CD8high αα+ T cells rather than other CD8 subpopulations were more responsive to ALV-J infections. On the other hand, genes involved in the “FoxO signaling pathway” and “TGF-beta signaling pathway” were most highly expressed in the CD4+CD8low+ (CD8low+) T cell population and the function of CD4+CD8low+ T cells may play roles in negatively regulating the functions of T cells based on the high expression of CCND1, ROCK1, FOXO1, FOXO3, TNFRSF18, and TNFRSF21. The selected gene expressions in CD8+ T cells and CD4+CD8low+ double-positive T cells confirmed by qRT-PCR matched the Smart-Seq2 data, indicating the reliability of the smart-seq results. The high expressions of Granzyme K, Granzyme A, and CCL5 indicated the positive response of CD8+ T cells. Conversely, CD4+CD8+ T cells may have the suppressor activity based on the low expression of activation molecules but high expression of T cell activity suppressor genes. These findings verified the heterogeneity and transcriptional differences of T cells expressing CD8 receptors in chicken PBMCs.

High-frequency and activation of CD4+CD25+ T cells maintain persistent immunotolerance induced by congenital ALV-J infection

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 CD4+CD25+ 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 CD4+CD25+ Tregs in blood and immune organs significantly increased, and the frequency of CD4+CD25+ Tregs was positively correlated with changes in ALV-J load in immune organs. Interestingly, CD4+CD25+ 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 CD4+CD25+ Tregs of ALV-J-infected chickens significantly increased. Together, high-frequency and activated CD4+CD25+ 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.

SOCS3 Promotes ALV-J Virus Replication via Inhibiting JAK2/STAT3 Phosphorylation During Infection.

Avian leukosis virus subgroup J (ALV-J) is an oncogenic retrovirus that causes immunosuppression and neoplastic diseases in poultry. Cytokine signal-transduction inhibitor molecule 3 (SOCS3) is an important negative regulator of the JAK2/STAT3 signaling pathway and plays certain roles in ALV-J infection. It is of significance to confirm the roles of SOCS3 in ALV-J infection and study how this gene affects ALV-J infection. In this study, we assessed the expression of the SOCS3 gene in vivo and in vitro, and investigated the roles of SOCS3 in ALV-J infection using overexpressed or interfered assays with the SOCS3 in DF-1 cells. The results showed that the SOCS3 expression of ALV-J infected chickens was different from uninfected chickens in the spleen, thymus and cecal tonsil. Further, SOCS3 is mainly expressed in the nucleus as determined by immunofluorescence assay. Overexpression of SOCS3 in DF-1 cells promoted the replication of ALV-J virus, and the expression of interferons (IFNα and INFβ), inflammatory factors (IL-6 and TNFα) along with interferon-stimulating genes (CH25H, MX1, OASL, and ZAP). Conversely, interference of SOCS3 showed the opposite results. We also observed that SOCS3 promoted ALV-J virus replication by inhibiting JAK2/STAT3 phosphorylation. In conclusion, SOCS3 promotes ALV-J replication via inhibiting the phosphorylation of the JAK2/STAT3 signaling pathway. These results would advance further understanding of the persistent infection and the viral immune evasion of the ALV-J virus.

Metabolomics profiling for identification of potential biomarkers in chickens infected with avian leukosis virus subgroup J (ALV-J)

There are currently no vaccines or effective drugs to prevent the disorders caused by avian leukosis virus subgroup J (ALV-J). Hence, it is critical to identify potential biomarkers in ALV-J-infected chickens to prevent ALV-J-induced disorders. We hypothesized that ALV-J infection alters metabolic profile in chickens. In the present study, a nontargeted metabolomics approach based on liquid chromatography coupled with mass spectrometry (LC-MS) was used to find differential metabolites in plasma samples from ALV-J-infected chickens and healthy controls. The parametric statistical test (Student's t-test) and fold change analysis were used for univariate analysis. Multivariate statistical analyses included principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). The levels of methyl bromide, pyraclonil, hexaflumuron, lythidathion, 3-phosphoglycerol-glutathione, bis-4-nitrophenyl phosphate, 4-ketocyclophosphamide, oxidized photinus luciferin, phenyl sulfate, and aryl sulfate significantly decreased, whereas the levels of 2-methylthiobenzothiazole, irinotecan, methadone, 3-o-ethyl-l-ascorbic acid, and o-acetylneuraminic acid markedly increased in ALV-J-infected chickens as compared to those in healthy controls. These data provide metabolic evidence and potential biomarkers for ALV-J-induced alterations in plasma metabolism.

The tyrosine phosphatase SHP-2 dephosphorylated by ALV-J via its Env efficiently promotes ALV-J replication

ABSTRACT 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 env 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) in vitro and in vivo. 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.