scholarly journals Review and Perspectives on the Structure–Function Relationships of the Gag Subunits of Feline Immunodeficiency Virus

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1502
Author(s):  
Mathieu Long ◽  
Johan Toesca ◽  
Christophe Guillon
Keyword(s):  
Human Immunodeficiency Virus ◽  
Structure Function ◽  
Feline Immunodeficiency Virus ◽  
Viral Genome ◽  
Structural Data ◽  
Supramolecular Architecture ◽  
Domestic Cats ◽  
Gag Polyprotein ◽  
Immunodeficiency Virus ◽  
Early Phases

The Gag polyprotein is implied in the budding as well as the establishment of the supramolecular architecture of infectious retroviral particles. It is also involved in the early phases of the replication of retroviruses by protecting and transporting the viral genome towards the nucleus of the infected cell until its integration in the host genome. Therefore, understanding the structure–function relationships of the Gag subunits is crucial as each of them can represent a therapeutic target. Though the field has been explored for some time in the area of Human Immunodeficiency Virus (HIV), it is only in the last decade that structural data on Feline Immunodeficiency Virus (FIV) Gag subunits have emerged. As FIV is an important veterinary issue, both in domestic cats and endangered feline species, such data are of prime importance for the development of anti-FIV molecules targeting Gag. This review will focus on the recent advances and perspectives on the structure–function relationships of each subunit of the FIV Gag polyprotein.

scholarly journals Immature HIV-1 Lattice Assembly Dynamics are Regulated by Scaffolding from Nucleic Acid and the Plasma Membrane

2017 ◽  
Author(s):  
Alexander J. Pak ◽  
John M. A. Grime ◽  
Prabuddha Sengupta ◽  
Antony K. Chen ◽  
Aleksander E. P. Durumeric ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Nucleic Acid ◽  
Structural Data ◽  
Single Particle Tracking ◽  
Coarse Grained ◽  
Intermediate Step ◽  
Amino Terminal ◽  
Gag Polyprotein ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACTThe packaging and budding of Gag polyprotein and viral ribonucleic acid (RNA) is a critical step in the human immunodeficiency virus-1 (HIV-1) lifecycle. High-resolution structures of the Gag polyprotein have revealed that the capsid (CA) and spacer peptide 1 (SP1) domains contain important interfaces for Gag self-assembly. However, the molecular details of the multimerization process, especially in the presence of RNA and the cell membrane, have remained unclear. In this work, we investigate the mechanisms that work in concert between the polyproteins, RNA, and membrane to promote immature lattice growth. We develop a coarse-grained (CG) computational model that is derived from sub-nanometer resolution structural data. Our simulations recapitulate contiguous and hexameric lattice assembly driven only by weak anisotropic attractions at the helical CA-SP1 junction. Importantly, analysis from CG and single-particle tracking photoactivated localization (spt-PALM) trajectories indicates that viral RNA and the membrane are critical constituents that actively promote Gag multimerization through scaffolding, while over-expression of short competitor RNA can suppress assembly. We also find that the CA amino-terminal domain imparts intrinsic curvature to the Gag lattice. As a consequence, immature lattice growth appears to be coupled to the dynamics of spontaneous membrane deformation. Our findings elucidate a simple network of interactions that regulate the early stages of HIV-1 assembly and budding.SIGNIFICANCE STATEMENTIn order for human immunodeficiency virus to proliferate, viral proteins and genomic dimers are assembled at host cell membranes and released as immature virions. Disrupting this key intermediate step in viral replication is a potential target for treatment. However, a detailed molecular view of this process remains lacking. Here, we elucidate a network of constitutive interactions that regulate viral assembly dynamics through a combined computational and experimental approach. Specifically, our analysis reveals the active roles of nucleic acid and the membrane as scaffolds that promote the multimerization of Gag polyprotein which proceeds through multi-step and self-correcting nucleation. Our findings also illustrate the functional importance of the N-terminal, C-terminal, and spacer peptide 1 protein domains.

Molecular Evidence for Nosocomial Transmission of Human Immunodeficiency Virus from a Surgeon to One of His Patients

1998 ◽  
Vol 72 (5) ◽  
pp. 4537-4540 ◽  
Author(s):  
Alain Blanchard ◽  
Stéphane Ferris ◽  
Sophie Chamaret ◽  
Denise Guétard ◽  
Luc Montagnier
Keyword(s):  
Human Immunodeficiency Virus ◽  
Viral Genome ◽  
Pcr Amplification ◽  
Nosocomial Transmission ◽  
Molecular Evidence ◽  
Immunodeficiency Virus ◽  
Reference Sequences ◽  
Hiv Type 1 ◽  
Viral Sequences

ABSTRACT We have investigated the molecular evidence in favor of the transmission of human immunodeficiency virus (HIV) from an HIV-infected surgeon to one of his patients. After PCR amplification, theenv and gag sequences from the viral genome were cloned and sequenced. Phylogenetic analysis revealed that the viral sequences derived from the surgeon and his patient are closely related, which strongly suggests that nosocomial transmission occurred. In addition, these viral sequences belong to group M of HIV type 1 but are divergent from the reference sequences of the known subtypes.

scholarly journals Mutations in the Human Immunodeficiency Virus Type 1 Integrase D,D(35)E Motif Do Not Eliminate Provirus Formation

1998 ◽  
Vol 72 (6) ◽  
pp. 4678-4685 ◽  
Author(s):  
Meenakshi Gaur ◽  
Andrew D. Leavitt
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Genome ◽  
Viral Dna ◽  
Infectious Titer ◽  
Immunodeficiency Virus ◽  
Acidic Residues ◽  
Hiv 1

ABSTRACT The core domain of human immunodeficiency virus type 1 (HIV-1) integrase (IN) contains a D,D(35)E motif, named for the phylogenetically conserved glutamic acid and aspartic acid residues and the invariant 35 amino acid spacing between the second and third acidic residues. Each acidic residue of the D,D(35)E motif is independently essential for the 3′-processing and strand transfer activities of purified HIV-1 IN protein. Using a replication-defective viral genome with a hygromycin selectable marker, we recently reported that a mutation at any of the three residues of the D,D(35)E motif produces a 103- to 104-fold reduction in infectious titer compared with virus encoding wild-type IN (A. D. Leavitt et al., J. Virol. 70:721–728. 1996). The infectious titer, as measured by the number of hygromycin-resistant colonies formed following infection of cells in culture, was less than a few hundred colonies per μg of p24. To understand the mechanism by which the mutant virions conferred hygromycin resistance, we characterized the integrated viral DNA in cells infected with virus encoding mutations at each of the three residues of the D,D(35)E motif. We found the integrated viral DNA to be colinear with the incoming viral genome. DNA sequencing of the junctions between integrated viral DNA and host DNA showed that (i) the characteristic 5-bp direct repeat of host DNA flanking the HIV-1 provirus was not maintained, (ii) integration often produced a deletion of host DNA, (iii) integration sometimes occurred without the viral DNA first undergoing 3′-processing, (iv) integration sites showed a strong bias for a G residue immediately adjacent to the conserved viral CA dinucleotide, and (v) mutations at each of the residues of the D,D(35)E motif produced essentially identical phenotypes. We conclude that mutations at any of the three acidic residues of the conserved D,D(35)E motif so severely impair IN activity that most, if not all, integration events by virus encoding such mutations are not IN mediated. IN-independent provirus formation may have implications for anti-IN therapeutic agents that target the IN active site.

scholarly journals Alix-Mediated Rescue of Feline Immunodeficiency Virus Budding Differs from That Observed with Human Immunodeficiency Virus

2020 ◽  
Vol 94 (11) ◽  
Author(s):  
Claudia Del Vecchio ◽  
Michele Celestino ◽  
Marta Celegato ◽  
Giorgio Palù ◽  
Cristina Parolin ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Feline Immunodeficiency Virus ◽  
Virus Assembly ◽  
Cellular Protein ◽  
Structural Protein ◽  
Virus Budding ◽  
Particle Assembly ◽  
Gag Protein ◽  
Double Mutation ◽  
Immunodeficiency Virus

ABSTRACT The structural protein Gag is the only viral component required for retroviral budding from infected cells. Each of the three conserved domains—the matrix (MA), capsid (CA), and nucleocapsid (NC) domains—drives different phases of viral particle assembly and egress. Once virus assembly is complete, retroviruses, like most enveloped viruses, utilize host proteins to catalyze membrane fission and to free progeny virions. These proteins are members of the endosomal sorting complex required for transport (ESCRT), a cellular machinery that coats the inside of budding necks to perform membrane-modeling events necessary for particle abscission. The ESCRT is recruited through interactions with PTAP and LYPXnL, two highly conserved sequences named late (L) domains, which bind TSG101 and Alix, respectively. A TSG101-binding L-domain was identified in the p2 region of the feline immunodeficiency virus (FIV) Gag protein. Here, we show that the human protein Alix stimulates the release of virus from FIV-expressing human cells. Furthermore, we demonstrate that the Alix Bro1 domain rescues FIV mutants lacking a functional TSG101-interacting motif, independently of the entire p2 region and of the canonical Alix-binding L-domain(s) in FIV Gag. However, in contrast to the effect on human immunodeficiency virus type 1 (HIV-1), the C377,409S double mutation, which disrupts both CCHC zinc fingers in the NC domain, does not abrogate Alix-mediated virus rescue. These studies provide insight into conserved and divergent mechanisms of lentivirus-host interactions involved in virus budding. IMPORTANCE FIV is a nonprimate lentivirus that infects domestic cats and causes a syndrome that is reminiscent of AIDS in humans. Based on its similarity to HIV with regard to different molecular and biochemical properties, FIV represents an attractive model for the development of strategies to prevent and/or treat HIV infection. Here, we show that the Bro1 domain of the human cellular protein Alix is sufficient to rescue the budding of FIV mutants devoid of canonical L-domains. Furthermore, we demonstrate that the integrity of the CCHC motifs in the Gag NC domain is dispensable for Alix-mediated rescue of virus budding, suggesting the involvement of other regions of the Gag viral protein. Our research is pertinent to the identification of a conserved yet mechanistically divergent ESCRT-mediated lentivirus budding process in general, and to the role of Alix in particular, which underlies the complex viral-cellular network of interactions that promote late steps of the retroviral life cycle.

scholarly journals Quantification of Feline immunodeficiency virus (FIVpco) in peripheral blood mononuclear cells, lymph nodes and plasma of naturally infected cougars

2006 ◽  
Vol 87 (4) ◽  
pp. 967-975 ◽  
Author(s):  
David J. Blake ◽  
Jon Graham ◽  
Mary Poss
Keyword(s):  
Virus Replication ◽  
Peripheral Blood Mononuclear Cells ◽  
Feline Immunodeficiency Virus ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Domestic Cats ◽  
Peripheral Blood Mononuclear ◽  
Viral Loads ◽  
Immunodeficiency Virus ◽  
Blood Mononuclear Cells

Infection of domestic cats with Feline immunodeficiency virus (FIV) results in a fatal immunodeficiency disease, similar to Human immunodeficiency virus 1 (HIV-1) in humans. Elevated plasma viral loads in domestic cats are correlated to decreased survival time and disease progression. However, FIV is also maintained as an apathogenic infection in other members of the family Felidae including cougars, Puma concolor (FIVpco). It is not known whether the lack of disease in cougars is a result of diminished virus replication. A real-time PCR assay was developed to quantify both FIVpco proviral and plasma viral loads in naturally infected cougars. Proviral loads quantified from peripheral blood mononuclear cells (PBMC) ranged from 2·90×101 to 6·72×104 copies per 106 cells. Plasma viral loads ranged from 2·30×103 to 2·81×106 RNA copies ml−1. These data indicate that FIVpco viral loads are comparable to viral loads observed in endemic and epidemic lentivirus infections. Thus, the lack of disease in cougars is not due to low levels of virus replication. Moreover, significant differences observed among cougar PBMC proviral loads correlated to viral lineage and cougar age (P=0·014), which suggests that separate life strategies exist within FIVpco lineages. This is the first study to demonstrate that an interaction of lentivirus lineage and host age significantly effect proviral loads.

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