scholarly journals Early Vertebrate Evolution of the Host Restriction Factor Tetherin

2015 ◽  
Vol 89 (23) ◽  
pp. 12154-12165 ◽  
Author(s):  
Elena Heusinger ◽  
Silvia F. Kluge ◽  
Frank Kirchhoff ◽  
Daniel Sauter
Keyword(s):  
Antiviral Activity ◽  
Sequence Homology ◽  
Transmembrane Domain ◽  
Arms Race ◽  
Evolutionary Origin ◽  
Vertebrate Evolution ◽  
Restriction Factor ◽  
Gpi Anchor ◽  
Enveloped Viruses ◽  
Virion Release

ABSTRACTTetherin is an interferon-inducible restriction factor targeting a broad range of enveloped viruses. Its antiviral activity depends on an unusual topology comprising an N-terminal transmembrane domain (TMD) followed by an extracellular coiled-coil region and a C-terminal glycosylphosphatidylinositol (GPI) anchor. One of the two membrane anchors is inserted into assembling virions, while the other remains in the plasma membrane of the infected cell. Thus, tetherin entraps budding viruses by physically bridging viral and cellular membranes. Although tetherin restricts the release of a large variety of diverse human and animal viruses, only mammalian orthologs have been described to date. Here, we examined the evolutionary origin of this protein and demonstrate that tetherin orthologs are also found in fish, reptiles, and birds. Notably, alligator tetherin efficiently blocks the release of retroviral particles. Thus, tetherin emerged early during vertebrate evolution and acquired its antiviral activity before the mammal/reptile divergence. Although there is only limited sequence homology, all orthologs share the typical topology. Two unrelated proteins of the slime moldDictyostelium discoideumalso adopt a tetherin-like configuration with an N-terminal TMD and a C-terminal GPI anchor. However, these proteins showed no evidence for convergent evolution and failed to inhibit virion release. In summary, our findings demonstrate that tetherin emerged at least 450 million years ago and is more widespread than previously anticipated. The early evolution of antiviral activity together with the high topology conservation but low sequence homology suggests that restriction of virus release is the primary function of tetherin.IMPORTANCEThe continuous arms race with viruses has driven the evolution of a variety of cell-intrinsic immunity factors that inhibit different steps of the viral replication cycle. One of these restriction factors, tetherin, inhibits the release of newly formed progeny virions from infected cells. Although tetherin targets a broad range of enveloped viruses, including retro-, filo-, herpes-, and arenaviruses, the evolutionary origin of this restriction factor and its antiviral activity remained obscure. Here, we examined diverse vertebrate genomes for genes encoding cellular proteins that share with tetherin the highly unusual combination of an N-terminal transmembrane domain and a C-terminal glycosylphosphatidylinositol anchor. We show that tetherin orthologs are found in fish, reptiles, and birds and demonstrate that alligator tetherin efficiently inhibits the release of retroviral particles. Our findings identify tetherin as an evolutionarily ancient restriction factor and provide new important insights into the continuous arms race between viruses and their hosts.

scholarly journals Smc5/6-antagonism by HBx is an evolutionary-conserved function of hepatitis B virus infection in mammals

2017 ◽  
Author(s):  
Fabien Filleton ◽  
Fabien Abdul ◽  
Laetitia Gerossier ◽  
Alexia Paturel ◽  
Janet Hall ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Antiviral Activity ◽  
Positive Selection ◽  
Host Species ◽  
Human Hepatocytes ◽  
Arms Race ◽  
Restriction Factor ◽  
Primary Human Hepatocytes ◽  
B Virus

AbstractInfection with Hepatitis B virus (HBV) is a major cause of liver disease and cancer in humans. HBVs (family Hepadnaviridae) have been associated with mammals for millions of years. Recently, the Smc5/6 complex, known for its essential housekeeping functions in genome maintenance, was identified as an antiviral restriction factor of human HBV. The virus has however developed a counteraction mechanism by degrading the complex via its regulatory HBx protein. Whether the antiviral activity of the Smc5/6 complex against hepadnaviruses is an important and evolutionary-conserved function is unknown. Here, we used a combined evolutionary and functional approach to address this question. We first performed phylogenetic and positive selection analyses of the six Smc5/6 complex subunits and found that they have been highly conserved in primates and mammals. Yet, the Smc6 subunit showed marks of adaptive evolution, potentially reminiscent of virus-host “arms-race” We then functionally tested the HBx from six very divergent hepadnaviruses now naturally infecting primates, rodents, and bats. Despite little sequence homology, we demonstrate that these HBx efficiently degraded mammalian Smc5/6 complexes, independently of the host species and of the sites under positive selection. Importantly, all also rescued the replication of an HBx-deficient HBV in primary human hepatocytes. These findings point to an evolutionary-conserved requirement for Smc5/6 inactivation by HBx, showing that the Smc5/6 antiviral activity has been an important defense mechanism against hepadnaviruses in mammals. Interestingly, Smc5/6 may further be a restriction factor of other yet unidentified viruses that have driven some of its adaptation.ImportanceInfection with hepatitis B virus (HBV) led to 887000 human deaths in 2015. HBV has been co-evolving with mammals for millions of years. Recently, the Smc5/6 complex, known for its essential housekeeping functions, was identified as a restriction factor of human HBV antagonized by the regulatory HBx protein. Here, we address whether the antiviral activity of Smc5/6 is an important evolutionary-conserved function. We found that all six subunits of Smc5/6 have been conserved in primates with only Smc6 showing signatures of “evolutionary arms-race” Using evolutionary-guided functional assays that include infections of primary human hepatocytes, we demonstrate that HBx from very divergent mammalian HBVs could all efficiently antagonize Smc5/6, independently of the host species and sites under positive selection. These findings show that the Smc5/6 antiviral activity against HBV is an important function in mammals. It also raises the intriguing possibility that Smc5/6 restricts other, yet unidentified viruses.

scholarly journals The Interferon-Inducible Protein Tetherin Inhibits Hepatitis B Virus Virion Secretion

2015 ◽  
Vol 89 (18) ◽  
pp. 9200-9212 ◽  
Author(s):  
Ran Yan ◽  
Xuesen Zhao ◽  
Dawei Cai ◽  
Yuanjie Liu ◽  
Timothy M. Block ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Multivesicular Body ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Gpi Anchor ◽  
Enveloped Viruses ◽  
Virion Release ◽  
B Virus ◽  
Subviral Particles

ABSTRACTInterferon alpha (IFN-α) is an approved medication for chronic hepatitis B therapy. Besides acting as an immunomodulator, IFN-α elicits a pleiotropic antiviral state in hepatitis B virus (HBV)-infected hepatocytes, but whether or not IFN-α impedes the late steps of the HBV life cycle, such as HBV secretion, remains elusive. Here we report that IFN-α treatment of HepAD38 cells with established HBV replication selectively reduced HBV virion release without altering intracellular viral replication or the secretion of HBV subviral particles and nonenveloped capsids. In search of the interferon-stimulated gene(s) that is responsible for the reduction of HBV virion release, we found that tetherin, a broad-spectrum antiviral transmembrane protein that inhibits the egress of a variety of enveloped viruses, was highly induced by IFN-α in HepAD38 cells and in primary human hepatocytes. We further demonstrated that the expression of full-length tetherin, but not the C-terminal glycosylphosphatidylinositol (GPI) anchor-truncated form, inhibited HBV virion egress from HepAD38 cells. In addition, GPI anchor-truncated tetherin exhibited a dominant-negative effect and was incorporated into the liberated virions. We also found colocalization of tetherin and HBV L protein at the intracellular multivesicular body, where the budding of HBV virions takes place. In line with this, electron microscopy demonstrated that HBV virions were tethered in the lumen of the cisterna membrane under tetherin expression. Finally, knockdown of tetherin or overexpression of dominant negative tetherin attenuated the IFN-α-mediated reduction of HBV virion release. Taken together, our study suggests that IFN-α inhibits HBV virion egress from hepatocytes through the induction of tetherin.IMPORTANCETetherin is a host restriction factor that blocks the egress of a variety of enveloped viruses through tethering the budding virions on the cell surface with its membrane anchor domains. Here we report that interferon directly and selectively inhibits the secretion of HBV virions, but not subviral particles or nonenveloped capsids, through the induction of tetherin in hepatocyte-derived cells. The antiviral function of tetherin requires the carboxyl-terminal GPI anchor, while the GPI anchor deletion mutant exhibits dominant negative activity and attaches to liberated HBV virions. Consistent with the fact that HBV is an intracellular budding virus, microscopy analyses demonstrated that the tethering of HBV virions occurs in the intracellular cisterna and that tetherin colocalizes with HBV virions on the multivesicular body, which is the HBV virion budding site. Our study not only expands the antiviral spectrum of tetherin but also sheds light on the mechanisms of interferon-elicited anti-HBV responses.

scholarly journals The Sheep Tetherin Paralog oBST2B Blocks Envelope Glycoprotein Incorporation into Nascent Retroviral Virions

2014 ◽  
Vol 89 (1) ◽  
pp. 535-544 ◽  
Author(s):  
Lita Murphy ◽  
Mariana Varela ◽  
Sophie Desloire ◽  
Najate Ftaich ◽  
Claudio Murgia ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Antiviral Activity ◽  
Vesicular Stomatitis Virus ◽  
Envelope Glycoprotein ◽  
Bone Marrow Stromal Cell ◽  
Restriction Factor ◽  
Enveloped Viruses ◽  
Viral Particles ◽  
Wide Range ◽  
Vesicular Stomatitis

ABSTRACTBone marrow stromal cell antigen 2 (BST2) is a cellular restriction factor with a broad antiviral activity. In sheep, theBST2gene is duplicated into two paralogs termedoBST2AandoBST2B. oBST2A impedes viral exit of the Jaagsiekte sheep retroviruses (JSRV), most probably by retaining virions at the cell membrane, similar to the “tethering” mechanism exerted by human BST2. In this study, we provide evidence that unlike oBST2A, oBST2B is limited to the Golgi apparatus and disrupts JSRV envelope (Env) trafficking by sequestering it. In turn, oBST2B leads to a reduction in Env incorporation into viral particles, which ultimately results in the release of virions that are less infectious. Furthermore, the activity of oBST2B does not seem to be restricted to retroviruses, as it also acts on vesicular stomatitis virus glycoproteins. Therefore, we suggest that oBST2B exerts antiviral activity using a mechanism distinct from the classical tethering restriction observed for oBST2A.IMPORTANCEBST2 is a powerful cellular restriction factor against a wide range of enveloped viruses. Sheep possess two paralogs of theBST2gene calledoBST2AandoBST2B. JSRV, the causative agent of a transmissible lung cancer of sheep, is known to be restricted by oBST2A. In this study, we show that unlike oBST2A, oBST2B impairs the normal cellular trafficking of JSRV envelope glycoproteins by sequestering them within the Golgi apparatus. We also show that oBST2B decreases the incorporation of envelope glycoprotein into JSRV viral particles, which in turn reduces virion infectivity. In conclusion, oBST2B exerts a novel antiviral activity that is distinct from those of BST2 proteins of other species.

scholarly journals Smc5/6 Antagonism by HBx Is an Evolutionarily Conserved Function of Hepatitis B Virus Infection in Mammals

2018 ◽  
Vol 92 (16) ◽  
Author(s):  
Fabien Abdul ◽  
Fabien Filleton ◽  
Laetitia Gerossier ◽  
Alexia Paturel ◽  
Janet Hall ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Antiviral Activity ◽  
Positive Selection ◽  
Defense Mechanism ◽  
Human Hepatocytes ◽  
Arms Race ◽  
Restriction Factor ◽  
Evolutionarily Conserved ◽  
B Virus

ABSTRACT Chronic infection with hepatitis B virus (HBV) is a major cause of liver disease and cancer in humans. HBVs (family Hepadnaviridae) have been associated with mammals for millions of years. Recently, the Smc5/6 complex, known for its essential housekeeping functions in genome maintenance, was identified as an antiviral restriction factor of human HBV. The virus has, however, evolved to counteract this defense mechanism by degrading the complex via its regulatory HBx protein. Whether the antiviral activity of the Smc5/6 complex against hepadnaviruses is an important and evolutionarily conserved function is unknown. In this study, we used an evolutionary and functional approach to address this question. We first performed phylogenetic and positive selection analyses of the Smc5/6 complex subunits and found that they have been conserved in primates and mammals. Yet, Smc6 showed marks of adaptive evolution, potentially reminiscent of a virus-host “arms race.” We then functionally tested the HBx proteins from six divergent hepadnaviruses naturally infecting primates, rodents, and bats. We demonstrate that despite little sequence homology, these HBx proteins efficiently degraded mammalian Smc5/6 complexes, independently of the host species and of the sites under positive selection. Importantly, all HBx proteins also rescued the replication of an HBx-deficient HBV in primary human hepatocytes. These findings point to an evolutionarily conserved requirement for Smc5/6 inactivation by HBx, showing that Smc5/6 antiviral activity has been an important defense mechanism against hepadnaviruses in mammals. It will be interesting to investigate whether Smc5/6 may further be a restriction factor of other, yet-unidentified viruses that may have driven some of its adaptation. IMPORTANCE Infection with hepatitis B virus (HBV) led to 887,000 human deaths in 2015. HBV has been coevolving with mammals for millions of years. Recently, the Smc5/6 complex, which has essential housekeeping functions, was identified as a restriction factor of human HBV antagonized by the regulatory HBx protein. Here we address whether the antiviral activity of Smc5/6 is an important evolutionarily conserved function. We found that all six subunits of Smc5/6 have been conserved in primates, with only Smc6 showing signatures of an “evolutionary arms race.” Using evolution-guided functional analyses that included infections of primary human hepatocytes, we demonstrated that HBx proteins from very divergent mammalian HBVs could all efficiently antagonize Smc5/6, independently of the host species and sites under positive selection. These findings show that Smc5/6 antiviral activity against HBV is an important function in mammals. They also raise the intriguing possibility that Smc5/6 may restrict other, yet-unidentified viruses.

scholarly journals Contribution of the Cytoplasmic Determinants of Vpu to the Expansion of Virus-Containing Compartments in HIV-1-Infected Macrophages

2019 ◽  
Vol 93 (11) ◽  
Author(s):  
Olivier Leymarie ◽  
Leslie Lepont ◽  
Margaux Versapuech ◽  
Delphine Judith ◽  
Sophie Abelanet ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Viral Particle ◽  
Transmembrane Domain ◽  
Immune Surveillance ◽  
Restriction Factor ◽  
Viral Particles ◽  
Protein Functions ◽  
Specific Accumulation ◽  
Model Cell ◽  
Hiv 1

ABSTRACTHIV-1 infection of macrophages leads to the sequestration of newly formed viruses in intracellular plasma membrane-connected structures termed virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The cellular restriction factor bone marrow stromal cell antigen 2 (BST2), which prevents HIV-1 dissemination by tethering budding viral particles at the plasma membrane, can be found in VCCs. The HIV-1 accessory protein Vpu counteracts the restriction factor BST2 by downregulating its expression and removing it from viral budding sites. Numerous studies described these Vpu countermeasures in CD4+T cells or model cell lines, but the interplay between Vpu and BST2 in VCC formation and HIV-1 production in macrophages is less explored. Here, we show that Vpu expression in HIV-1-infected macrophages enhances viral release. This effect is related to Vpu’s ability to circumvent BST2 antiviral activity. We show that in absence of Vpu, BST2 is enriched in VCCs and colocalizes with capsid p24, whereas Vpu expression significantly reduces the presence of BST2 in these compartments. Furthermore, our data reveal that BST2 is dispensable for the formation of VCCs and that Vpu expression impacts the volume of these compartments. This Vpu activity partly depends on BST2 expression and requires the integrity of the Vpu transmembrane domain, the dileucine-like motif E59XXXLV64and phosphoserines 52 and 56 of Vpu. Altogether, these results highlight that Vpu controls the volume of VCCs and promotes HIV-1 release from infected macrophages.IMPORTANCEHIV-1 infection of macrophages leads to the sequestration of newly formed viruses in virus-containing compartments (VCCs), where virions remain infectious and hidden from immune surveillance. The restriction factor BST2, which prevents HIV-1 dissemination by tethering budding viral particles, can be found in VCCs. The HIV-1 Vpu protein counteracts BST2. This study explores the interplay between Vpu and BST2 in the viral protein functions on HIV-1 release and viral particle sequestration in VCCs in macrophages. The results show that Vpu controls the volume of VCCs and favors viral particle release. These Vpu functions partly depend on Vpu’s ability to antagonize BST2. This study highlights that the transmembrane domain of Vpu and two motifs of the Vpu cytoplasmic domain are required for these functions. These motifs were notably involved in the control of the volume of VCCs by Vpu but were dispensable for the prevention of the specific accumulation of BST2 in these structures.

Antiviral activity of uridine 5′-diphosphate glucose analogues against some enveloped viruses in cell culture

1987 ◽  
Vol 8 (5-6) ◽  
pp. 299-310 ◽  
Author(s):  
G. Gil-Fernández ◽  
S. Pérez ◽  
P. Vilas ◽  
C. Pérez ◽  
F.G. de las Heras ◽  
...  
Keyword(s):  
Cell Culture ◽  
Antiviral Activity ◽  
Enveloped Viruses ◽  
Glucose Analogues ◽  
Diphosphate Glucose

scholarly journals Nanodroplet-Benzalkonium Chloride Formulation Demonstrates In Vitro and Ex- Vivo Broad-Spectrum Antiviral Activity Against SARS-CoV-2 and other Enveloped Viruses

2021 ◽  
Author(s):  
Jessie Pannu ◽  
Susan Ciotti ◽  
Shyamala Ganesan ◽  
George Arida ◽  
Chad Costley ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Broad Spectrum ◽  
Benzalkonium Chloride ◽  
Ex Vivo ◽  
Viral Disease ◽  
Influenza B ◽  
Human Coronavirus ◽  
Enveloped Viruses ◽  
Nasal Irritation

Abstract Objective: The Covid-19 pandemic has highlighted the importance of aerosolized droplets inhaled into the nose in the transmission of respiratory viral disease. Inactivating pathogenic viruses at the nasal port of entry may reduce viral loads, thereby reducing infection, transmission and spread. In this communication, we demonstrate safe and broad anti-viral activity of oil-in-water nanoemulsion (nanodroplet) formulation containing the potent antiseptic 0.13% Benzalkonium Chloride (NE-BZK). Results: We have demonstrated that NE-BZK exhibits broad-spectrum, long-lasting antiviral activity with >99.9% in vitro killing of enveloped viruses including SARS-CoV-2, human coronavirus, RSV, and influenza B. In vitro and ex-vivo studies demonstrated continued killing of >99.99% of human coronavirus with diluted NE-BZK and persistent for 8 hours post application, respectively. The repeated application of NE-BZK, twice daily for 2 weeks into rabbit nostrils demonstrated its safety with no nasal irritation. These findings demonstrate that formulating BZK into the proprietary nanodroplets offers a safe and effective antiviral and a significant addition to strategies to combat the spread of respiratory viral infectious diseases.

scholarly journals Upregulation of BST-2 by Type I Interferons Reduces the Capacity of Vpu To Protect HIV-1-Infected Cells from NK Cell Responses

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Jérémie Prévost ◽  
Suzanne Pickering ◽  
Mitchell J. Mumby ◽  
Halima Medjahed ◽  
Gabrielle Gendron-Lepage ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Nk Cell ◽  
Restriction Factor ◽  
Type I ◽  
Cell Responses ◽  
Viral Release ◽  
Type I Ifns ◽  
Infected Cells ◽  
Ifn Treatment ◽  
Hiv 1

ABSTRACTThe HIV-1 accessory protein Vpu enhances viral release by counteracting the restriction factor BST-2. Furthermore, Vpu promotes NK cell evasion by downmodulating cell surface NTB-A and PVR, known ligands of the NK cell receptors NTB-A and DNAM-1, respectively. While it has been established that Vpu’s transmembrane domain (TMD) is required for the interaction and intracellular sequestration of BST-2, NTB-A, and PVR, it remains unclear how Vpu manages to target these proteins simultaneously. In this study, we show that upon upregulation, BST-2 is preferentially downregulated by Vpu over its other TMD substrates. We found that type I interferon (IFN)-mediated BST-2 upregulation greatly impairs the ability of Vpu to downregulate NTB-A and PVR. Our results suggest that occupation of Vpu by BST-2 affects its ability to downregulate other TMD substrates. Accordingly, knockdown of BST-2 increases Vpu’s potency to downmodulate NTB-A and PVR in the presence of type I IFN treatment. Moreover, we show that expression of human BST-2, but not that of the macaque orthologue, decreases Vpu’s capacity to downregulate NTB-A. Importantly, we show that type I IFNs efficiently sensitize HIV-1-infected cells to NTB-A- and DNAM-1-mediated direct and antibody-dependent NK cell responses. Altogether, our results reveal that type I IFNs decrease Vpu’s polyfunctionality, thus reducing its capacity to protect HIV-1-infected cells from NK cell responses.IMPORTANCEThe restriction factor BST-2 and the NK cell ligands NTB-A and PVR are among a growing list of membrane proteins found to be downregulated by HIV-1 Vpu. BST-2 antagonism enhances viral release, while NTB-A and PVR downmodulation contributes to NK cell evasion. However, it remains unclear how Vpu can target multiple cellular factors simultaneously. Here we provide evidence that under physiological conditions, BST-2 is preferentially targeted by Vpu over NTB-A and PVR. Specifically, we show that type I IFNs decrease Vpu’s polyfunctionality by upregulating BST-2, thus reducing its capacity to protect HIV-1-infected cells from NK cell responses. This indicates that there is a hierarchy of Vpu substrates upon IFN treatment, revealing that for the virus, targeting BST-2 as part of its resistance to IFN takes precedence over evading NK cell responses. This reveals a potential weakness in HIV-1’s immunoevasion mechanisms that may be exploited therapeutically to harness NK cell responses against HIV-1.

scholarly journals Antiviral Activity and Adaptive Evolution of Avian Tetherins

2020 ◽  
Vol 94 (12) ◽  
Author(s):  
Veronika Krchlíková ◽  
Helena Fábryová ◽  
Tomáš Hron ◽  
Janet M. Young ◽  
Anna Koslová ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Recent Work ◽  
Avian Species ◽  
Domestic Chicken ◽  
Restriction Factor ◽  
Restriction Factors ◽  
Zoonotic Infections ◽  
Avian Viruses ◽  
Avian Sarcoma ◽  
Hiv 1

ABSTRACT Tetherin/BST-2 is an antiviral protein that blocks the release of enveloped viral particles by linking them to the membrane of producing cells. At first, BST-2 genes were described only in humans and other mammals. Recent work identified BST-2 orthologs in nonmammalian vertebrates, including birds. Here, we identify the BST-2 sequence in domestic chicken (Gallus gallus) for the first time and demonstrate its activity against avian sarcoma and leukosis virus (ASLV). We generated a BST-2 knockout in chicken cells and showed that BST-2 is a major determinant of an interferon-induced block of ASLV release. Ectopic expression of chicken BST-2 blocks the release of ASLV in chicken cells and of human immunodeficiency virus type 1 (HIV-1) in human cells. Using metabolic labeling and pulse-chase analysis of HIV-1 Gag proteins, we verified that chicken BST-2 blocks the virus at the release stage. Furthermore, we describe BST-2 orthologs in multiple avian species from 12 avian orders. Previously, some of these species were reported to lack BST-2, highlighting the difficulty of identifying sequences of this extremely variable gene. We analyzed BST-2 genes in the avian orders Galliformes and Passeriformes and showed that they evolve under positive selection. This indicates that avian BST-2 is involved in host-virus evolutionary arms races and suggests that BST-2 antagonists exist in some avian viruses. In summary, we show that chicken BST-2 has the potential to act as a restriction factor against ASLV. Characterizing the interaction of avian BST-2 with avian viruses is important in understanding innate antiviral defenses in birds. IMPORTANCE Birds are important hosts of viruses that have the potential to cause zoonotic infections in humans. However, only a few antiviral genes (called viral restriction factors) have been described in birds, mostly because birds lack counterparts of highly studied mammalian restriction factors. Tetherin/BST-2 is a restriction factor, originally described in humans, that blocks the release of newly formed virus particles from infected cells. Recent work identified BST-2 in nonmammalian vertebrate species, including birds. Here, we report the BST-2 sequence in domestic chicken and describe its antiviral activity against a prototypical avian retrovirus, avian sarcoma and leukosis virus (ASLV). We also identify BST-2 genes in multiple avian species and show that they evolve rapidly in birds, which is an important indication of their relevance for antiviral defense. Analysis of avian BST-2 genes will shed light on defense mechanisms against avian viral pathogens.

Sign in / Sign up

Export Citation Format

Share Document