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Wang XF, Zhang X, Ma W, Li J, Wang X. Host cell restriction factors of equine infectious anemia virus. Virol Sin 2023; 38:485-496. [PMID: 37419416 PMCID: PMC10436108 DOI: 10.1016/j.virs.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023] Open
Abstract
Equine infectious anemia virus (EIAV) is a member of the lentivirus genus in the Retroviridae family and is considered an animal model for HIV/AIDS research. An attenuated EIAV vaccine, which was successfully developed in the 1970s by classical serial passage techniques, is the first and only lentivirus vaccine that has been widely used to date. Restriction factors are cellular proteins that provide an early line of defense against viral replication and spread by interfering with various critical steps in the viral replication cycle. However, viruses have evolved specific mechanisms to overcome these host barriers through adaptation. The battle between the viruses and restriction factors is actually a natural part of the viral replication process, which has been well studied in human immunodeficiency virus type 1 (HIV-1). EIAV has the simplest genome composition of all lentiviruses, making it an intriguing subject for understanding how the virus employs its limited viral proteins to overcome restriction factors. In this review, we summarize the current literature on the interactions between equine restriction factors and EIAV. The features of equine restriction factors and the mechanisms by which the EIAV counteract the restriction suggest that lentiviruses employ diverse strategies to counteract innate immune restrictions. In addition, we present our insights on whether restriction factors induce alterations in the phenotype of the attenuated EIAV vaccine.
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Affiliation(s)
- Xue-Feng Wang
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Xiangmin Zhang
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Weiwei Ma
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Jiwei Li
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Xiaojun Wang
- State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin 150069, China.
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SYNJ2BP Improves the Production of Lentiviral Envelope Protein by Facilitating the Formation of Mitochondrion-Associated Endoplasmic Reticulum Membrane. J Virol 2022; 96:e0054922. [PMID: 36197105 PMCID: PMC9599250 DOI: 10.1128/jvi.00549-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Equine infectious anemia virus (EIAV) and HIV are both members of the Lentivirus genus and are similar in major virological characters. EIAV endangers the horse industry. In addition, EIAV can also be used as a model for HIV research. The maturation of the lentiviral Env protein, which is necessary for viral entry, requires Env to be folded in the endoplasmic reticulum (ER). It is currently unclear how this process is regulated. Mitochondrion-associated endoplasmic reticulum membrane (MAM) is a specialized part of the close connection between the ER and mitochondria, and one of the main functions of MAM is to promote oxidative protein production in the ER. SYNJ2BP is one of the key proteins that make up the MAM, and we found that SYNJ2BP is essential for EIAV replication. We therefore constructed a SYNJ2BP knockout HEK293T cell line in which the number of MAMs is significantly reduced. Moreover, overexpression of SYNJ2BP could increase the number of MAMs. Our study demonstrates that SYNJ2BP can improve the infectivity of the EIAV virus with elevated production of the viral Env protein through increased MAM formation. Interestingly, SYNJ2BP was able to improve the production of not only EIAV Env but also HIV. Further investigation showed that MAMs can provide more ATP and calcium ions, which are essential factors for Env production, to the ER and can also reduce ER stress induced by HIV or EIAV Envs to increase the Env production level in cells. These results may help us to understand the key production mechanisms of lentiviral Env. IMPORTANCE Lentiviral Env proteins, which are rich in disulfide bonds, need to be fully folded in the ER; otherwise, misfolded Env proteins will induce ER stress and be degraded by ER-associated protein degradation (ERAD). To date, it is still unclear about Env production mechanism in the ER. MAM is the structure of closely connection between the ER and mitochondria. MAMs play important roles in the calcium steady state and oxidative stress, especially in the production of oxidative protein. For the first time, we found that SYNJ2BP can promote the production of lentiviral Env proteins by providing the ATP and calcium ions required for oxidative protein production in the ER and by reducing ER stress through facilitating formation of MAMs. These studies shed light on how MAMs improve lentiviral Env production, which will lay the foundation for the study of replication mechanisms in other lentiviruses from the perspective of the cellular organelle microenvironment.
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A Novel, Fully Spliced, Accessory Gene in Equine Lentivirus with Distinct Rev-Responsive Element. J Virol 2022; 96:e0098622. [PMID: 36069548 PMCID: PMC9517694 DOI: 10.1128/jvi.00986-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
All lentiviruses encode the accessory protein Rev, whose main biological function is to mediate the nuclear export of unspliced and incompletely spliced viral transcripts by binding to a viral cis-acting element (termed the Rev-responsive element, RRE) within the env-encoding region. Equine infectious anemia virus (EIAV) is a member of the lentivirus genus in the Retroviridae family and is considered an important model for the study of lentivirus pathogenesis. Here, we identified a novel transcript from the EIAV genome that encoded a viral protein, named Mat, with an unknown function. The transcript mat was fully spliced and comprised parts of the coding regions of MA and TM. Interestingly, the expression of Mat depended on Rev and the chromosome region maintenance 1 (CRM1) pathway. Rev could specifically bind to Mat mRNA to promote its nuclear export. We further identified that the first exon of Mat mRNA, which was located within the Gag-encoding region, acted as an unreported RRE. Altogether, we identified a novel fully spliced transcript mat with an unusual RRE, which interacted with Rev for nuclear export through the CRM1 pathway. These findings updated the EIAV genome structure, highlighted the diversification of posttranscriptional regulation patterns in EIAV, and may help to expand the understanding of gene transcription and expression of lentivirus. IMPORTANCE In lentiviruses, the nuclear export of viral transcripts is an important step in controlling viral gene expression. Generally, the unspliced and incompletely spliced transcripts are exported via the CRM1-dependent export pathway in a process mediated by the viral Rev protein by binding to the Rev-responsive element (RRE) located within the Env-coding region. However, the completely spliced transcripts are exported via an endogenous cellular pathway, which was Rev independent. Here, we identified a novel fully spliced transcript from EIAV and demonstrated that it encoded a viral protein, termed Mat. Interestingly, we determined that the expression of Mat depended on Rev and identified that the first exon of Mat mRNA could specifically bind to Rev and be exported to the cytoplasm, which suggested that the first exon of Mat mRNA was a second RRE of EIAV. These findings provided important insights into the Rev-dependent nuclear export of completely spliced transcripts in lentiviruses.
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Ren H, Yin X, Su C, Guo M, Wang XF, Na L, Lin Y, Wang X. Equine lentivirus counteracts SAMHD1 restriction by Rev-mediated degradation of SAMHD1 via the BECN1-dependent lysosomal pathway. Autophagy 2021; 17:2800-2817. [PMID: 33172327 PMCID: PMC8525956 DOI: 10.1080/15548627.2020.1846301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 10/16/2020] [Accepted: 10/30/2020] [Indexed: 02/09/2023] Open
Abstract
The innate immune restriction factor SAMHD1 can inhibit diverse viruses in myeloid cells. Mechanistically, SAMHD1 inhibits lentiviral replication including HIV-1 by depleting the nucleotide pool to interfere with their reverse transcription. Equine infectious anemia virus (EIAV) is an ancient lentivirus that preferentially attacks macrophages. However, the mechanism by which EIAV successfully establishes infection in macrophages with functional SAMHD1 remains unclear. Here, we demonstrate that while equine SAMDH1 can limit EIAV replication in equine macrophages at the reverse transcription stage, the antiviral effect is counteracted by the well-known transcriptional regulator Rev, which downregulates equine SAMHD1 through the lysosomal pathway. Remarkably, Rev hijacks BECN1 (beclin 1) and PIK3C3 to mediate SAMHD1 degradation in a canonical macroautophagy/autophagy-independent pathway. Our study illustrates that equine lentiviral Rev possesses important functions in evading cellular innate immunity in addition to its RNA regulatory function, and may provide new insights into the co-evolutionary arms race between SAMHD1 and lentiviruses.Abbreviations:3-MA: 3-methyladenine; AA: amino acid; ACTB: actin beta; AD: activation domain; ATG: autophagy related; Baf A1: bafilomycin A1; BD: binding domain; BECN1: beclin 1; BH3: BCL2-homology-3 domain; BiFC: bimolecular fluorescence complementation; CCD: coiled-coil domain; class III PtdIns3K: class III phosphatidylinositol 3-kinase; CQ: chloroquine; Co-IP: co-immunoprecipitation; dNTPase: dGTP-stimulated deoxynucleoside triphosphate triphosphohydrolase; ECD: evolutionarily conserved domain; EIAV: equine infectious anemia virus; eMDMs: equine monocyte-derived macrophages; GFP: green fluorescent protein; HD: histidine-aspartic; HIV-1: human immunodeficiency virus-1; hpi: hours post infection; hpt: hours post transfection; KO: knockout; LAMP2: lysosomal associated membrane protein 2; LMB: leptomycin B; PMA: phorbol 12-myristate 13-acetate; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; ND: unknown non-essential domain; NES: nuclear export signal; NLS: localization signal; NS: statistically non-significant; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; RBD: RNA binding domain; RT: reverse transcriptase; siRNAs: small interfering RNAs; SAMHD1: SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1; SIV: simian immunodeficiency virus; VN: C-terminal residues of Venus 174 to 238; VC: N-terminal residues 2 to 173 of Venus.
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Affiliation(s)
- Huiling Ren
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Xin Yin
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Chao Su
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Miaomiao Guo
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Xue-Feng Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Lei Na
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yuezhi Lin
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
| | - Xiaojun Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, the Chinese Academy of Agricultural Sciences, Harbin, China
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Lin Y, Wang XF, Wang Y, Du C, Ren H, Liu C, Zhu D, Chen J, Na L, Liu D, Yang Z, Wang X. Env diversity-dependent protection of the attenuated equine infectious anaemia virus vaccine. Emerg Microbes Infect 2021; 9:1309-1320. [PMID: 32525460 PMCID: PMC7473056 DOI: 10.1080/22221751.2020.1773323] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Lentiviruses harbour high genetic variability for efficient evasion from host immunity.
An attenuated equine infectious anaemia (EIA) vaccine was developed decades ago in China
and presented remarkably robust protection against EIA. The vaccine was recently proven to
have high genomic diversity, particular in env. However, how
and to what extent the high env diversity relates to immune
protection remains unclear. In this study, we compared immune protections and responses of
three groups of horses stimulated by the high-diversity vaccine EIAV_HD, a single
molecular clone of the vaccine EIAV_LD with low env
diversity, as well as a constructed vaccine strain EIAV_MD with moderate env diversity. The disparity of virus-host interactions between
three env diversity-varied groups (5 horses in each group)
was evaluated using clinical manifestation, pathological scores, and env-specific antibody. We found the highest titres of env antibodies (Abs) or neutralizing Abs (nAbs) in the EIAV_HD group, followed
by the EIAV_MD group, and the lowest titres in the EIAV_LD group (P<0.05). The occurrence of disease/death was different between EIAV_HD
group (1/0), EIAV_MD (2/2), and EIAV_LD group (4/2). A similar env diversity-related linear relationship was observed in the clinical
manifestations and pathological changes. This diversity-dependent disparity in changes
between the three groups was more distinct after immunosuppression, suggesting that
env diversity plays an important role in protection under
low host immunocompetence. In summary, inoculation with vaccines with higher genetic
diversity could present broader and more efficient protection. Our findings strongly
suggest that an abundance of Env antigens are required for efficient protection against
lentiviruses.
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Affiliation(s)
- Yuezhi Lin
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Xue-Feng Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China.,Shanghai Key Laboratory of Veterinary Biotechnology, Shanghai, People's Republic of China
| | - Yuhong Wang
- Department of Geriatrics and Gerontology, First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China
| | - Cheng Du
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Huiling Ren
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Cong Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Dantong Zhu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Jie Chen
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Lei Na
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Diqiu Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
| | - Zhibiao Yang
- Shanghai Key Laboratory of Veterinary Biotechnology, Shanghai, People's Republic of China
| | - Xiaojun Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, People's Republic of China
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Bai B, Wang XF, Zhang M, Na L, Zhang X, Zhang H, Yang Z, Wang X. The N-glycosylation of Equine Tetherin Affects Antiviral Activity by Regulating Its Subcellular Localization. Viruses 2020; 12:v12020220. [PMID: 32079099 PMCID: PMC7077275 DOI: 10.3390/v12020220] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/28/2020] [Accepted: 02/12/2020] [Indexed: 01/08/2023] Open
Abstract
Tetherin is an interferon-inducible type II transmembrane glycoprotein which inhibits the release of viruses, including retroviruses, through a “physical tethering” model. However, the role that the glycosylation of tetherin plays in its antiviral activity remains controversial. In this study, we found that mutation of N-glycosylation sites resulted in an attenuation of the antiviral activity of equine tetherin (eqTHN), as well as a reduction in the expression of eqTHN at the plasma membrane (PM). In addition, eqTHN N-glycosylation mutants colocalize obviously with ER, CD63, LAMP1 and endosomes, while WT eqTHN do not. Furthermore, we also found that N-glycosylation impacts the transport of eqTHN in the cell not by affecting the endocytosis, but rather by influencing the anterograde trafficking of the protein. These results suggest that the N-glycosylation of eqTHN is important for the antiviral activity of the protein through regulating its normal subcellular localization. This finding will enhance our understanding of the function of this important restriction factor.
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Affiliation(s)
- Bowen Bai
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.B.); (X.-F.W.); (M.Z.); (L.N.); (X.Z.); (H.Z.)
| | - Xue-Feng Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.B.); (X.-F.W.); (M.Z.); (L.N.); (X.Z.); (H.Z.)
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China;
| | - Mengmeng Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.B.); (X.-F.W.); (M.Z.); (L.N.); (X.Z.); (H.Z.)
| | - Lei Na
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.B.); (X.-F.W.); (M.Z.); (L.N.); (X.Z.); (H.Z.)
| | - Xiangmin Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.B.); (X.-F.W.); (M.Z.); (L.N.); (X.Z.); (H.Z.)
| | - Haili Zhang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.B.); (X.-F.W.); (M.Z.); (L.N.); (X.Z.); (H.Z.)
| | - Zhibiao Yang
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China;
| | - Xiaojun Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Harbin 150069, China; (B.B.); (X.-F.W.); (M.Z.); (L.N.); (X.Z.); (H.Z.)
- Correspondence: ; Tel.: +86-451-5105-1749
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