Fungal Ice2p Has Remote Homology to SERINCs, Restriction Factors for HIV and Other Viruses

The Bunyavirales order comprises more than 500 viruses (generally defined as bunyaviruses) classified into 12 families. Some of these are highly pathogenic viruses infecting different hosts, including humans, mammals, reptiles, arthropods, birds, and/or plants. Host cell sensing of infection activates the innate immune system that aims at inhibiting viral replication and propagation. Upon recognition of pathogen-associated molecular patterns (PAMPs) by cellular pattern recognition receptors (PRRs), numerous signaling cascades are activated, leading to the production of interferons (IFNs). IFNs act in an autocrine and paracrine manner to establish an antiviral state by inducing the expression of hundreds of IFN-stimulated genes (ISGs). Some of these ISGs are known to restrict bunyavirus infection. Along with other constitutively expressed host cellular factors with antiviral activity, these proteins (hereafter referred to as “restriction factors”) target different steps of the viral cycle, including viral entry, genome transcription and replication, and virion egress. In reaction to this, bunyaviruses have developed strategies to circumvent this antiviral response, by avoiding cellular recognition of PAMPs, inhibiting IFN production or interfering with the IFN-mediated response. Herein, we review the current knowledge on host cellular factors that were shown to restrict infections by bunyaviruses. Moreover, we focus on the strategies developed by bunyaviruses in order to escape the antiviral state developed by the infected cells.

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Foamy Viruses, Bet, and APOBEC3 Restriction

Viruses ◽

10.3390/v13030504 ◽

2021 ◽

Vol 13 (3) ◽

pp. 504

Author(s):

Ananda Ayyappan Jaguva Vasudevan ◽

Daniel Becker ◽

Tom Luedde ◽

Holger Gohlke ◽

Carsten Münk

Keyword(s):

Current Knowledge ◽

Regulatory Protein ◽

Host Population ◽

Life Cycles ◽

Restriction Factors ◽

Host Restriction ◽

Open Questions ◽

Foamy Viruses ◽

Natural Hosts ◽

Hiv 1

Non-human primates (NHP) are an important source of viruses that can spillover to humans and, after adaptation, spread through the host population. Whereas HIV-1 and HTLV-1 emerged as retroviral pathogens in humans, a unique class of retroviruses called foamy viruses (FV) with zoonotic potential are occasionally detected in bushmeat hunters or zookeepers. Various FVs are endemic in numerous mammalian natural hosts, such as primates, felines, bovines, and equines, and other animals, but not in humans. They are apathogenic, and significant differences exist between the viral life cycles of FV and other retroviruses. Importantly, FVs replicate in the presence of many well-defined retroviral restriction factors such as TRIM5α, BST2 (Tetherin), MX2, and APOBEC3 (A3). While the interaction of A3s with HIV-1 is well studied, the escape mechanisms of FVs from restriction by A3 is much less explored. Here we review the current knowledge of FV biology, host restriction factors, and FV–host interactions with an emphasis on the consequences of FV regulatory protein Bet binding to A3s and outline crucial open questions for future studies.

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Structure, Function, and Interactions of the HIV-1 Capsid Protein

Life ◽

10.3390/life11020100 ◽

2021 ◽

Vol 11 (2) ◽

pp. 100

Author(s):

Eric Rossi ◽

Megan E. Meuser ◽

Camille J. Cunanan ◽

Simon Cocklin

Keyword(s):

Life Cycle ◽

Capsid Protein ◽

Adaptor Proteins ◽

Restriction Factors ◽

Gag Polyprotein ◽

Immunodeficiency Virus ◽

Host Cell Factors ◽

Hiv 1

The capsid (CA) protein of the human immunodeficiency virus type 1 (HIV-1) is an essential structural component of a virion and facilitates many crucial life cycle steps through interactions with host cell factors. Capsid shields the reverse transcription complex from restriction factors while it enables trafficking to the nucleus by hijacking various adaptor proteins, such as FEZ1 and BICD2. In addition, the capsid facilitates the import and localization of the viral complex in the nucleus through interaction with NUP153, NUP358, TNPO3, and CPSF-6. In the later stages of the HIV-1 life cycle, CA plays an essential role in the maturation step as a constituent of the Gag polyprotein. In the final phase of maturation, Gag is cleaved, and CA is released, allowing for the assembly of CA into a fullerene cone, known as the capsid core. The fullerene cone consists of ~250 CA hexamers and 12 CA pentamers and encloses the viral genome and other essential viral proteins for the next round of infection. As research continues to elucidate the role of CA in the HIV-1 life cycle and the importance of the capsid protein becomes more apparent, CA displays potential as a therapeutic target for the development of HIV-1 inhibitors.

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High Natural Permissivity of Primary Rabbit Cells for HIV-1, with a Virion Infectivity Defect in Macrophages as the Final Replication Barrier

Journal of Virology ◽

10.1128/jvi.01607-10 ◽

2010 ◽

Vol 84 (23) ◽

pp. 12300-12314 ◽

Cited By ~ 14

Author(s):

Hanna-Mari Tervo ◽

Oliver T. Keppler

Keyword(s):

T Cells ◽

Late Phase ◽

Small Animal ◽

Receptor Complex ◽

Restriction Factors ◽

Cyclin T1 ◽

Primary Rabbit ◽

Species Specific ◽

Hiv 1

ABSTRACT An immunocompetent, permissive, small-animal model would be valuable for the study of human immunodeficiency virus type 1 (HIV-1) pathogenesis and for the testing of drug and vaccine candidates. However, the development of such a model has been hampered by the inability of primary rodent cells to efficiently support several steps of the HIV-1 replication cycle. Although transgenesis of the HIV receptor complex and human cyclin T1 have been beneficial, additional late-phase blocks prevent robust replication of HIV-1 in rodents and limit the range of in vivo applications. In this study, we explored the HIV-1 susceptibility of rabbit primary T cells and macrophages. Envelope-specific and coreceptor-dependent entry of HIV-1 was achieved by expressing human CD4 and CCR5. A block of HIV-1 DNA synthesis, likely mediated by TRIM5, was overcome by limited changes to the HIV-1 gag gene. Unlike with mice and rats, primary cells from rabbits supported the functions of the regulatory viral proteins Tat and Rev, Gag processing, and the release of HIV-1 particles at levels comparable to those in human cells. While HIV-1 produced by rabbit T cells was highly infectious, a macrophage-specific infectivity defect became manifest by a complex pattern of mutations in the viral genome, only part of which were deamination dependent. These results demonstrate a considerable natural HIV-1 permissivity of the rabbit species and suggest that receptor complex transgenesis combined with modifications in gag and possibly vif of HIV-1 to evade species-specific restriction factors might render lagomorphs fully permissive to infection by this pathogenic human lentivirus.

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Cell-to-cell transmission of retroviruses: Innate immunity and interferon-induced restriction factors

Virology ◽

10.1016/j.virol.2010.12.031 ◽

2011 ◽

Vol 411 (2) ◽

pp. 251-259 ◽

Cited By ~ 27

Author(s):

Clare Jolly

Keyword(s):

Innate Immunity ◽

Restriction Factors ◽

Cell Transmission

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Sequence analysis identified an HTLV-1 subtype and mutations of host restriction factors susceptible to HAM/TSP

Journal of the Neurological Sciences ◽

10.1016/j.jns.2017.08.2839 ◽

2017 ◽

Vol 381 ◽

pp. 1006

Author(s):

S. Nozuma ◽

E. Matsuura ◽

T. Matsuzaki ◽

D. Kodama ◽

R. Kubota ◽

...

Keyword(s):

Sequence Analysis ◽

Restriction Factors ◽

Host Restriction ◽

Host Restriction Factors

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Cellular Restriction Factors of Feline Immunodeficiency Virus

Viruses ◽

10.3390/v3101986 ◽

2011 ◽

Vol 3 (10) ◽

pp. 1986-2005 ◽

Cited By ~ 13

Author(s):

Jörg Zielonka ◽

Carsten Münk

Keyword(s):

Feline Immunodeficiency Virus ◽

Restriction Factors ◽

Immunodeficiency Virus

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Amphotericin b effect on the sensitivity to influenza infection of WI-38 VA-13 cells with IFITM3 gene knockout

Medical academic journal ◽

10.17816/maj76106 ◽

2021 ◽

Vol 21 (3) ◽

pp. 109-112

Author(s):

Kira S. Koryabina ◽

Mariya V. Sergeeva ◽

Andrey B. Komissarov ◽

Nataliya V. Eshchenko ◽

Grigoriy A. Stepanov

Keyword(s):

Amphotericin B ◽

Influenza A Virus ◽

Influenza A ◽

Gene Knockout ◽

Influenza Infection ◽

Restriction Factors ◽

Host Restriction ◽

Host Restriction Factors ◽

Infected Cells ◽

The Difference

BACKGROUND: The application of CRISPR/Cas9 is one of the most rapidly developing areas in biotechnology. This method was used to obtain clones of а human origin cell line with knockout of one or more genes of the IFITM family, representing host restriction factors for influenza infection. Amphotericin B has previously been shown to promote influenza infection by blocking IFITM3 function. AIM: The aim of this study was to evaluate the effect of amphotericin B on the sensitivity of IFITM knockout cells to influenza A virus infection. MATERIALS AND METHODS: WI-38 VA-13 cells and mutant clones with IFITM3 knockout (F3 clone) or IFITM1, IFITM3 knockout (clone E12) were infected with influenza virus A/PR/8/34 (H1N1) in the presence or absence of amphotericin B. Forty-four hours after infection, the culture medium was taken to determine the infectious activity of the virus by titration in the MDCK cell culture, as well as the hemagglutinating activity of the virus. The infected cells were stained with fluorescently labeled antibodies against the viral NP protein, and the number of NP-positive cells was determined by flow cytometry. RESULTS: The addition of amphotericin B increased the hemagglutinating and infectious activity of the virus in WI-38 VA-13cells, while the difference was insignificant for clones with IFITM gene knockout. A similar dependency was obtained for the percent of infected cells. CONCLUSIONS: Mutant cells with a knockout of one or several genes of the IFITM family were equally susceptible to influenza infection regardless of the addition of amphotericin B, which confirms the crucial importance of a defect in the IFITM3 protein in increasing the permissiveness of cells to influenza A virus.

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