scholarly journals Equine Infectious Anemia Virus Gag p9 Function in Early Steps of Virus Infection and Provirus Production

2005 ◽  
Vol 79 (14) ◽  
pp. 8793-8801 ◽  
Author(s):  
Sha Jin ◽  
Chaoping Chen ◽  
Ronald C. Montelaro
Keyword(s):  
Amino Acids ◽  
Equine Infectious Anemia Virus ◽  
Critical Role ◽  
Productive Infection ◽  
Viral Dna ◽  
Virus Particles ◽  
Viral Budding ◽  
Equine Infectious Anemia ◽  
Anemia Virus ◽  
First Time

ABSTRACT We have previously reported that serial truncation of the Gag p9 protein of equine infectious anemia virus (EIAV) revealed a progressive loss in replication phenotypes in transfected cells, such that a proviral mutant (E32) expressing the N-terminal 31 amino acids of p9 produced infectious virus particles similarly to parental provirus, while a proviral mutant (K30) with two fewer amino acids produced replication-defective virus particles, despite containing apparently normal levels of processed Gag and Pol proteins (C. Chen, F. Li, and R. C. Montelaro, J. Virol. 75:9762-9760, 2001). Based on these observations, we sought in the current study to identify the precise defect in K30 virion infection of permissive equine dermal (ED) cells. The results of these experiments clearly demonstrated that K30 virions entered target ED cells and produced early (minus-strand strong-stop) and late (Gag) viral DNA products as efficiently as did the replication-competent E32 mutant and parental EIAVUK viruses. However, in contrast to the replication-competent E32 mutant and parental viruses, infection with K30 mutant virus failed to produce detectable two-long-terminal-repeat DNA circles, stable integrated provirus, virus-specific Gag mRNA expression, or intracellular viral protein expression. Taken together, these data demonstrate that the K30 mutant is defective in the ability to produce sufficient nuclear viral DNA to establish a productive infection in ED cells. Thus, these observations indicate for the first time that the EIAV Gag p9 protein performs a critical role in viral DNA production and processing to provirus during EIAV infection, in addition to its previously defined role in viral budding mediated by the p9 L domain.

scholarly journals S2 from Equine infectious anemia virus is an infectivity factor which counteracts the retroviral inhibitors SERINC5 and SERINC3

2016 ◽  
Author(s):  
Ajit Chande ◽  
Cristiana Cuccurullo ◽  
Annachiara Rosa ◽  
Serena Ziglio ◽  
Susan Carpenter ◽  
...  
Keyword(s):  
Equine Infectious Anemia Virus ◽  
Critical Role ◽  
Host Factor ◽  
Target Cells ◽  
Accessory Protein ◽  
Post Translational Modification ◽  
Virus Particles ◽  
Equine Infectious Anemia ◽  
Anemia Virus ◽  
Hiv 1

ABSTRACTThe lentivirus equine infectious anemia virus (EIAV) encodes S2, a pathogenic determinant important for virus replication and disease progression in horses. No molecular function has yet been linked to this accessory protein. We now report that S2 can replace the activity of Nef on HIV-1 infectivity, being required to antagonize the inhibitory activity of SERINC proteins on Nef-defective HIV-1. Similar to Nef, S2 excludes SERINC5 from virus particles and requires an ExxxLL motif predicted to recruit the clathrin adaptor AP2. Accordingly, a functional endocytic machinery is essential for S2-mediated infectivity enhancement, which is impaired by inhibitors of clathrin-mediated endocytosis. In addition to retargeting SERINC5 to a late endosomal compartment, S2 promotes the host factor degradation. Emphasizing the similarity with Nef, we show that S2 is myristoylated and, compatible with a crucial role of the post-translational modification, its N-terminal glycine is required for the anti-SERINC5 activity.EIAV-derived vectors devoid of S2 are less susceptible than HIV-1 to the inhibitory effect of both human and equine SERINC5. We then identified the envelope glycoprotein of EIAV as a determinant which also modulates retrovirus susceptibility to SERINC5, indicating a bi-modular ability of the equine lentivirus to counteract the host factor.S2 shares no sequence homology with other retroviral factors known to counteract SERINC5. Adding to primate lentivirus Nef and gammaretrovirus glycoGag, the accessory protein from EIAV makes another example of a retroviral virulence determinant which independently evolved SERINC5-antagonizing activity. SERINC5 therefore plays a critical role for the interaction of the host with diverse retrovirus pathogens.Significance StatementSERINC5 and SERINC3 are recently discovered cellular inhibitors of retroviruses, which are incorporated into virus particles and impair their ability to propagate the infection to target cells. Only two groups of viruses (represented by HIV-1 and MLV) have so far been identified to have evolved the ability of counteracting SERINC inhibition. We now discovered that Equine infectious anemia virus, which causes a debilitating disease in horses, also acquired the ability to protect the virus particle from inhibition by SERINC5 and SERINC3, using its small protein S2. The evidence that three different retroviruses have independently evolved the ability to elude inhibition bySERINC5 and SERINC3 indicates that these cellular factors play a fundamental role against various retrovirus pathogens.

scholarly journals Functional Roles of Equine Infectious Anemia Virus Gag p9 in Viral Budding and Infection

2001 ◽  
Vol 75 (20) ◽  
pp. 9762-9770 ◽  
Author(s):  
Chaoping Chen ◽  
Feng Li ◽  
Ronald C. Montelaro
Keyword(s):  
Amino Acids ◽  
Equine Infectious Anemia Virus ◽  
Virus Assembly ◽  
Virus Budding ◽  
Gag Protein ◽  
Functional Roles ◽  
Gag Polyprotein ◽  
Viral Budding ◽  
Equine Infectious Anemia ◽  
Anemia Virus

ABSTRACT Previous studies utilizing Gag polyprotein budding assays with transfected cells reveal that the equine infectious anemia virus (EIAV) Gag p9 protein provides a late assembly function mediated by a critical Y23P24D25L26 motif (L-domain) to release viral particles from the plasma membrane. To elucidate further the role of EIAV p9 in virus assembly and replication, we have examined the replication properties of a defined series of p9 truncation and site-directed mutations in the context of a reference infectious molecular proviral clone, EIAVuk. Characterization of these p9 proviral mutants revealed new functional properties of p9 in EIAV replication, not previously elucidated by Gag polyprotein budding assays. The results of these studies demonstrated that only the N-terminal 31 amino acids of a total of 51 residues in the complete p9 protein were required to maintain replication competence in transfected equine cells; proviral mutants with p9 C-terminal truncations of 20 or fewer amino acids remained replication competent, while mutants with truncations of 21 or more residues were completely replication defective. The inability of the defective p9 proviral mutations to produce infectious virus could not be attributed to defects in Gag polyprotein expression or processing, in virion RT activity, or in virus budding. While proviral replication competence appeared to be associated with the presence of a K30K31 motif and potential ubiquitination of the EIAV p9 protein, mutations of these lysine residues to methionines produced variant proviruses that replicated as well as the parental EIAVuk in transfected ED cells. Thus, these observations reveal for the first time that EIAV p9 is not absolutely required for virus budding in the context of proviral gene expression, suggesting that other EIAV proteins can at least in part mediate late budding functions previously associated with the p9 protein. In addition, the data define a function for EIAV p9 in the infectivity of virus particles, indicating a previously unrecognized role for this Gag protein in EIAV replication.

scholarly journals The S2 Gene of Equine Infectious Anemia Virus Is Dispensable for Viral Replication In Vitro

1998 ◽  
Vol 72 (10) ◽  
pp. 8344-8348 ◽  
Author(s):  
Feng Li ◽  
Bridget A. Puffer ◽  
Ronald C. Montelaro
Keyword(s):  
Equine Infectious Anemia Virus ◽  
Parental Virus ◽  
Target Cells ◽  
Monocyte Differentiation ◽  
Cell Culture Systems ◽  
Equine Infectious Anemia ◽  
Anemia Virus ◽  
First Time

ABSTRACT Equine infectious anemia virus (EIAV) contains the simplest genome among lentiviruses in that it encodes only three putative regulatory genes (S1, S2, S3) in addition to the canonical gag, pol, and envgenes, presumably reflecting its limited tropism to cells of monocyte/macrophage lineage. Tat and Rev functions have been assigned to S1 and S3, respectively, but the specific function for the S2 gene has yet to be determined. Thus, the function of S2 in virus replication in vitro was investigated by using an infectious molecular viral clone, EIAVUK. Various EIAVUK mutants lackingS2 were constructed, and their replication kinetics were examined in several equine cell culture systems, including the natural in vivo target equine macrophage cells. The EIAV S2 mutants showed replication kinetics similar to those of the parental virus in all of the tested primary and transformed equine cell cultures, without any detectable reversion of mutant genomes. The EIAVUKmutants also showed replication kinetics similar to those of the parental virus in an equine blood monocyte differentiation-maturation system. These results demonstrate for the first time that the EIAVS2 gene is not essential and does not appear to affect virus infection and replication properties in target cells in vitro.

scholarly journals High Genomic Variability in Equine Infectious Anemia Virus Obtained from Naturally Infected Horses in Pantanal, Brazil: An Endemic Region Case

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 207 ◽  
Author(s):  
Camila Dantas Malossi ◽  
Eduardo Gorzoni Fioratti ◽  
Jedson Ferreira Cardoso ◽  
Angelo Jose Magro ◽  
Erna Geessien Kroon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Equine Infectious Anemia Virus ◽  
Genomic Sequences ◽  
Endemic Region ◽  
Viral Genomes ◽  
Equine Infectious Anemia ◽  
Anemia Virus ◽  
Next Generation Sequencing Ngs ◽  
First Time ◽  
Generation Sequencing

Equine infectious anemia virus (EIAV) is a persistent lentivirus that causes equine infectious anemia (EIA). In Brazil, EIAV is endemic in the Pantanal region, and euthanasia is not mandatory in this area. All of the complete genomic sequences from field viruses are from North America, Asia, and Europe, and only proviral genomic sequences are available. Sequences from Brazilian EIAV are currently available only for gag and LTR regions. Thus, the present study aimed for the first time to sequence the entire EIAV genomic RNA in naturally infected horses from an endemic area in Brazil. RNA in plasma from naturally infected horses was used for next-generation sequencing (NGS), and gaps were filled using Sanger sequencing methodology. Complete viral genomes of EIAV from two horses were obtained and annotated (Access Number: MN560970 and MN560971). Putative genes were analyzed and compared with previously described genes, showing conservation in gag and pol genes and high variations in LTR and env sequences. Amino acid changes were identified in the p26 protein, one of the most common targets used for diagnosis, and p26 molecular modelling showed surface amino acid alterations in some epitopes. Brazilian genome sequences presented 88.6% nucleotide identity with one another and 75.8 to 77.3% with main field strains, such as EIAV Liaoning, Wyoming, Ireland, and Italy isolates. Furthermore, phylogenetic analysis suggested that this Brazilian strain comprises a separate monophyletic group. These results may help to better characterize EIAV and to overcome the challenges of diagnosing and controlling EIA in endemic regions.

scholarly journals Tissue Sites of Persistent Infection and Active Replication of Equine Infectious Anemia Virus during Acute Disease and Asymptomatic Infection in Experimentally Infected Equids

2000 ◽  
Vol 74 (7) ◽  
pp. 3112-3121 ◽  
Author(s):  
Sharon M. Harrold ◽  
Sheila J. Cook ◽  
R. Frank Cook ◽  
Keith E. Rushlow ◽  
Charles J. Issel ◽  
...  
Keyword(s):  
Viral Infection ◽  
Virus Replication ◽  
Equine Infectious Anemia Virus ◽  
Clinical Symptoms ◽  
Acute Disease ◽  
Viral Dna ◽  
Dna And Rna ◽  
Equine Infectious Anemia ◽  
Anemia Virus

ABSTRACT Equine infectious anemia virus (EIAV) infection of horses is characterized by recurring cycles of disease and viremia that typically progress to an inapparent infection in which clinical symptoms are absent as host immune responses maintain control of virus replication indefinitely. The dynamics of EIAV viremia and its association with disease cycles have been well characterized, but there has been to date no comprehensive quantitative analyses of the specific tissue sites of EIAV infection and replication in experimentally infected equids during acute disease episodes and during asymptomatic infections in long-term inapparent carriers. To characterize the in vivo site(s) of viral infection and replication, we developed a quantitative competitive PCR assay capable of detecting 10 copies of viral DNA and a quantitative competitive reverse transcription-PCR assay with a sensitivity of about 30 copies of viral singly spliced mRNA. Animals were experimentally infected with one of two reference viruses: the animal-passaged field isolate designated EIAVWyo and the virulent cell-adapted strain designated EIAVPV. Tissues and blood cells were isolated during the initial acute disease or from asymptomatic animals and analyzed for viral DNA and RNA levels by the respective quantitative assays. The results of these experiments demonstrated that the appearance of clinical symptoms in experimentally infected equids coincided with rapid widespread seeding of viral infection and replication in a variety of tissues. During acute disease, the predominant cellular site of viral infection and replication was the spleen, which typically accounted for over 90% of the cellular viral burden. In asymptomatic animals, viral DNA and RNA persisted in virtually all tissues tested, but at extremely low levels, a finding indicative of tight but incomplete immune control of EIAV replication. During all disease states, peripheral blood mononuclear cells (PBMC) were found to harbor less than 1% of the cellular viral burden. These quantitative studies demonstrate that tissues, rather than PBMC, constitute the predominant sites of virus replication during acute disease in infected equids and serve as resilient reservoirs of virus infection, even in the presence of highly effective immune responses that maintain a stringent control of virus replication in long-term inapparent carriers. Thus, these observations with EIAV, a predominantly macrophage-tropic lentivirus, highlight the role of tissues in sequestering lentiviral infections from host immune surveillance.

scholarly journals Equine Endothelial Cells Support Productive Infection of Equine Infectious Anemia Virus

1998 ◽  
Vol 72 (11) ◽  
pp. 9291-9297 ◽  
Author(s):  
Wendy Maury ◽  
J. Lindsay Oaks ◽  
Sarahann Bradley
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Equine Infectious Anemia Virus ◽  
High Titer ◽  
Productive Infection ◽  
Cell Type ◽  
Cell Infection ◽  
Equine Infectious Anemia ◽  
Anemia Virus

ABSTRACT Previous cell infectivity studies have demonstrated that the lentivirus equine infectious anemia virus (EIAV) infects tissue macrophages in vivo and in vitro. In addition, some strains of EIAV replicate to high titer in vitro in equine fibroblasts and fibroblast cell lines. Here we report a new cell type, macrovascular endothelial cells, that is infectible with EIAV. We tested the ability of EIAV to infect purified endothelial cells isolated from equine umbilical cords and renal arteries. Infectivity was detected by cell supernatant reverse transcriptase positivity, EIAV antigen positivity within individual cells, and the detection of viral RNA by in situ hybridization. Virus could rapidly spread through the endothelial cultures, and the supernatants of infected cultures contained high titers of infectious virus. There was no demonstrable cell killing in infected cultures. Three of four strains of EIAV that were tested replicated in these cultures, including MA-1, a fibroblast-tropic strain, Th.1, a macrophage-tropic strain, and WSU5, a strain that is fibroblast tropic and can cause disease. Finally, upon necropsy of a WSU5-infected horse 4 years postinfection, EIAV-positive endothelial cells were detected in outgrowths of renal artery cultures. These findings identify a new cell type that is infectible with EIAV. The role of endothelial cell infection in the course of equine infectious anemia is currently unknown, but endothelial cell infection may be involved in the edema that can be associated with infection. Furthermore, the ability of EIAV to persistently infect endothelial cultures and the presence of virus in endothelial cells from a long-term carrier suggest that this cell type can serve as a reservoir for the virus during subclinical phases of infection.

scholarly journals Influence of Long Terminal Repeat and Env on the Virulence Phenotype of Equine Infectious Anemia Virus

2004 ◽  
Vol 78 (5) ◽  
pp. 2478-2485 ◽  
Author(s):  
Susan L. Payne ◽  
Xiao-fang Pei ◽  
Bin Jia ◽  
Angela Fagerness ◽  
Frederick J. Fuller
Keyword(s):  
Amino Acids ◽  
Equine Infectious Anemia Virus ◽  
Lethal Dose ◽  
Acute Disease ◽  
Transcriptional Enhancer ◽  
Infectious Dose ◽  
Virulence Phenotype ◽  
Equine Infectious Anemia ◽  
Anemia Virus

ABSTRACT The molecular clones pSPeiav19 and p19/wenv17 of equine infectious anemia virus (EIAV) differ in env and long terminal repeats (LTRs) and produce viruses (EIAV19 and EIAV17, respectively) of dramatically different virulence phenotypes. These constructs were used to generate a series of chimeric clones to test the individual contributions of LTR, surface (SU), and transmembrane (TM)/Rev regions to the disease potential of the highly virulent EIAV17. The LTRs of EIAV19 and EIAV17 differ by 16 nucleotides in the transcriptional enhancer region. The two viruses differ by 30 amino acids in SU, by 17 amino acids in TM, and by 8 amino acids in Rev. Results from in vivo infections with chimeric clones indicate that both LTR and env of EIAV17 are required for the development of severe acute disease. In the context of the EIAV17 LTR, SU appears to have a greater impact on virulence than does TM. EIAV17SU, containing only the TM/Rev region from the avirulent parent, induced acute disease in two animals, while a similar infectious dose of EIAV17TM (which derives SU from the avirulent parent) did not. Neither EIAV17SU nor EIAV17TM produced lethal disease when administered at infectious doses that were 6- to 30-fold higher than a lethal dose of the parental EIAV17. All chimeric clones replicated in primary equine monocyte-derived macrophages, and there was no apparent correlation between macrophage tropism and virulence phenotype.

scholarly journals S2 from equine infectious anemia virus is an infectivity factor which counteracts the retroviral inhibitors SERINC5 and SERINC3

2016 ◽  
Vol 113 (46) ◽  
pp. 13197-13202 ◽  
Author(s):  
Ajit Chande ◽  
Emilia Cristiana Cuccurullo ◽  
Annachiara Rosa ◽  
Serena Ziglio ◽  
Susan Carpenter ◽  
...  
Keyword(s):  
Equine Infectious Anemia Virus ◽  
Critical Role ◽  
Adaptor Protein ◽  
Inhibitory Effect ◽  
Host Factor ◽  
Accessory Protein ◽  
Endocytic Machinery ◽  
Equine Infectious Anemia ◽  
Anemia Virus ◽  
Hiv 1

The lentivirus equine infectious anemia virus (EIAV) encodes the small protein S2, a pathogenic determinant that is important for virus replication and disease progression in horses. No molecular function had been linked to this accessory protein. We report that S2 can replace the activity of Negative factor (Nef) in HIV-1 infectivity, being required to antagonize the inhibitory activity of Serine incorporator (SERINC) proteins on Nef-defective HIV-1. Like Nef, S2 excludes SERINC5 from virus particles and requires an ExxxLL motif predicted to recruit the clathrin adaptor, Adaptor protein 2 (AP2). Accordingly, functional endocytic machinery is essential for S2-mediated infectivity enhancement, and S2-mediated enhancement is impaired by inhibitors of clathrin-mediated endocytosis. In addition to retargeting SERINC5 to a late endosomal compartment, S2 promotes host factor degradation. Emphasizing the similarity with Nef, we show that S2 is myristoylated, and, as is compatible with a crucial role in posttranslational modification, its N-terminal glycine is required for anti-SERINC5 activity. EIAV-derived vectors devoid of S2 are less susceptible than HIV-1 to the inhibitory effect of both human and equine SERINC5. We then identified the envelope glycoprotein of EIAV as a determinant that also modulates retroviral susceptibility to SERINC5, indicating that EIAV has a bimodal ability to counteract the host factor. S2 shares no sequence homology with other retroviral factors known to counteract SERINC5. Like the primate lentivirus Nef and the gammaretrovirus glycoGag, the accessory protein from EIAV is an example of a retroviral virulence determinant that independently evolved SERINC5-antagonizing activity. SERINC5 therefore plays a critical role in the interaction of the host with diverse retrovirus pathogens.

scholarly journals Replication of Equine Infectious Anemia Virus in Engineered Mouse NIH 3T3 Cells

2008 ◽  
Vol 83 (4) ◽  
pp. 2034-2037 ◽  
Author(s):  
Baoshan Zhang ◽  
Ronald C. Montelaro
Keyword(s):  
Equine Infectious Anemia Virus ◽  
3T3 Cells ◽  
Cyclin T1 ◽  
Immunodeficiency Virus ◽  
Equine Infectious Anemia ◽  
Anemia Virus ◽  
Nih 3T3 ◽  
First Time ◽  
Hiv 1 ◽  
Nih 3T3 Cells

ABSTRACT We employed the equine lentivirus equine infectious anemia virus (EIAV) to investigate the cellular restrictions for lentivirus replication in murine NIH 3T3 cells. The results of these studies demonstrate that NIH 3T3 cells expressing the EIAV receptor ELR1 and equine cyclin T1 supported productive replication of EIAV and produced infectious virions at levels similar to those found in a reference permissive equine cell line. The studies presented here demonstrate, for the first time, differential levels of restriction for EIAV and human immunodeficiency virus type 1 (HIV-1) replication in murine cells and suggest that these differences can be exploited to reveal critical virus-cell interactions required for HIV-1 assembly and budding of lentivirus particles.

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