scholarly journals The C-Terminal End of HIV-1 Vpu Has a Clade-Specific Determinant That Antagonizes BST-2 and Facilitates Virion Release

2019 ◽  
Vol 93 (11) ◽  
Author(s):  
Shilpi Sharma ◽  
Moein Jafari ◽  
Amandip Bangar ◽  
Karen William ◽  
John Guatelli ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Chronic Infection ◽  
High Surface ◽  
Human Populations ◽  
Accessory Proteins ◽  
Virion Assembly ◽  
Virion Release ◽  
Clade B ◽  
Clade C ◽  
Hiv 1

ABSTRACTThe cellular protein bone marrow stromal antigen-2 (BST-2)/tetherin acts against a variety of enveloped viruses by restricting their release from the plasma membrane. The HIV-1 accessory protein Vpu counteracts BST-2 by downregulating it from the cell surface and displacing it from virion assembly sites. Previous comparisons of Vpus from transmitted/founder viruses and between viruses isolated during acute and chronic infection led to the identification of a tryptophan at position 76 in Vpu (W76) as a key determinant for the displacement of BST-2 from virion assembly sites. Although present in Vpus from clades B, D, and G, W76 is absent from Vpus from clades A, C, and H. Mutagenesis of the C-terminal region of Vpu from two clade C viruses led to the identification of a conserved LL sequence that is functionally analogous to W76 of clade B. Alanine substitution of these leucines partially impaired virion release. This impairment was even greater when the mutations were combined with mutations of the Vpu β-TrCP binding site, resulting in Vpu proteins that induced high surface levels of BST-2 and reduced the efficiency of virion release to less than that of virus lackingvpu. Microscopy confirmed that these C-terminal leucines in clade C Vpu, like W76 in clade B, contribute to virion release by supporting the displacement of BST-2 from virion assembly sites. These results suggest that although encoded differently, the ability of Vpu to displace BST-2 from sites of virion assembly on the plasma membrane is evolutionarily conserved among clade B and C HIV-1 isolates.IMPORTANCEAlthough targeted by a variety of restriction mechanisms, HIV-1 establishes chronic infection in most cases, in part due to the counteraction of these host defenses by viral accessory proteins. Using conserved motifs, the accessory proteins exploit the cellular machinery to degrade or mistraffic host restriction factors, thereby counteracting them. The Vpu protein counteracts the virion-tethering factor BST-2 in part by displacing it from virion assembly sites along the plasma membrane, but a previously identified determinant of that activity is clade specific at the level of protein sequence and not found in the clade C viruses that dominate the pandemic. Here, we show that clade C Vpu provides this activity via a leucine-containing sequence rather than the tryptophan-containing sequence found in clade B Vpu. This difference seems likely to reflect the different evolutionary paths taken by clade B and clade C HIV-1 in human populations.

scholarly journals CCL2 mobilizes ALIX to facilitate Gag-p6 mediated HIV-1 virion release

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
David O Ajasin ◽  
Vasudev R Rao ◽  
Xuhong Wu ◽  
Santhamani Ramasamy ◽  
Mario Pujato ◽  
...  
Keyword(s):  
Virus Replication ◽  
Virus Production ◽  
Escrt Machinery ◽  
Virion Release ◽  
Clade B ◽  
Novel Variants ◽  
Clade C ◽  
Extracellular Stimuli ◽  
First Time ◽  
Hiv 1

Cellular ESCRT machinery plays pivotal role in HIV-1 budding and release. Extracellular stimuli that modulate HIV-1 egress are currently unknown. We found that CCL2 induced by HIV-1 clade B (HIV-1B) infection of macrophages enhanced virus production, while CCL2 immuno-depletion reversed this effect. Additionally, HIV-1 clade C (HIV-1C) was refractory to CCL2 levels. We show that CCL2-mediated increase in virus production requires Gag late motif LYPX present in HIV-1B, but absent in HIV-1C, and ALIX protein that recruits ESCRT III complex. CCL2 immuno-depletion sequestered ALIX to F-actin structures, while CCL2 addition mobilized it to cytoplasm facilitating Gag-ALIX binding. The LYPX motif improves virus replication and its absence renders the virus less fit. Interestingly, novel variants of HIV-1C with PYRE/PYKE tetrapeptide insertions in Gag-p6 conferred ALIX binding, CCL2-responsiveness and enhanced virus replication. These results, for the first time, indicate that CCL2 mediates ALIX mobilization from F-actin and enhances HIV-1 release and fitness.

scholarly journals Griffithsin Retains Anti-HIV-1 Potency with Changes in gp120 Glycosylation and Complements Broadly Neutralizing Antibodies PGT121 and PGT126

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Kathryn Fischer ◽  
Kimberly Nguyen ◽  
Patricia J. LiWang
Keyword(s):  
Neutralizing Antibodies ◽  
Glycosylation Site ◽  
Significant Loss ◽  
Broadly Neutralizing Antibodies ◽  
Clade B ◽  
Key Factor ◽  
Clade C ◽  
Cd4 Binding Site ◽  
Gp120 Glycosylation ◽  
Hiv 1

ABSTRACT Griffithsin (Grft) is an antiviral lectin that has been shown to potently inhibit HIV-1 by binding high-mannose N-linked glycosylation sites on HIV-1 gp120. A key factor for Grft potency is glycosylation at N295 of gp120, which is directly adjacent to N332, a target glycan for an entire class of broadly neutralizing antibodies (bNAbs). Here, we unify previous work on the importance of other glycans to Grft potency against HIV-1 and Grft’s role in mediating the conformational change of gp120 by mutating nearly every glycosylation site in gp120. In addition to a significant loss of Grft activity by the removal of glycosylation at N295, glycan absence at N332 or N448 was found to have moderate effects on Grft potency. Interestingly, in the absence of N295, Grft effectiveness could be improved by a mutation that results in the glycan at N448 shifting to N446, indicating that the importance of individual glycans may be related to their effect on glycosylation density. Grft’s ability to alter the structure of gp120, exposing the CD4 binding site, correlated with the presence of glycosylation at N295 only in clade B strains, not clade C strains. We further demonstrate that Grft can rescue the activity of the bNAbs PGT121 and PGT126 in the event of a loss or a shift of glycosylation at N332, where the bNAbs suffer a drastic loss of potency. Despite targeting the same region, Grft in combination with PGT121 and PGT126 produced additive effects. This indicates that Grft could be an important combinational therapeutic.

scholarly journals Plasma Membrane-Associated Restriction Factors and Their Counteraction by HIV-1 Accessory Proteins

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1020 ◽  
Author(s):  
Ramirez ◽  
Sharma ◽  
Singh ◽  
Stoneham ◽  
Vollbrecht ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Immune Surveillance ◽  
Viral Envelope ◽  
Accessory Proteins ◽  
Host Defenses ◽  
Restriction Factors ◽  
Associated Proteins ◽  
Infected Cells ◽  
Hiv 1

The plasma membrane is a site of conflict between host defenses and many viruses. One aspect of this conflict is the host’s attempt to eliminate infected cells using innate and adaptive cell-mediated immune mechanisms that recognize features of the plasma membrane characteristic of viral infection. Another is the expression of plasma membrane-associated proteins, so-called restriction factors, which inhibit enveloped virions directly. HIV-1 encodes two countermeasures to these host defenses: The membrane-associated accessory proteins Vpu and Nef. In addition to inhibiting cell-mediated immune-surveillance, Vpu and Nef counteract membrane-associated restriction factors. These include BST-2, which traps newly formed virions at the plasma membrane unless counteracted by Vpu, and SERINC5, which decreases the infectivity of virions unless counteracted by Nef. Here we review key features of these two antiviral proteins, and we review Vpu and Nef, which deplete them from the plasma membrane by co-opting specific cellular proteins and pathways of membrane trafficking and protein-degradation. We also discuss other plasma membrane proteins modulated by HIV-1, particularly CD4, which, if not opposed in infected cells by Vpu and Nef, inhibits viral infectivity and increases the sensitivity of the viral envelope glycoprotein to host immunity.

scholarly journals Genetic identity, biological phenotype, and evolutionary pathways of transmitted/founder viruses in acute and early HIV-1 infection

2009 ◽  
Vol 206 (6) ◽  
pp. 1273-1289 ◽  
Author(s):  
Jesus F. Salazar-Gonzalez ◽  
Maria G. Salazar ◽  
Brandon F. Keele ◽  
Gerald H. Learn ◽  
Elena E. Giorgi ◽  
...  
Keyword(s):  
Direct Analysis ◽  
Cytotoxic T Cell ◽  
Adaptive Mutations ◽  
Clade B ◽  
Single Genome ◽  
Coreceptor Binding ◽  
Clade C ◽  
Biological Phenotype ◽  
Cytotoxic T Cell Responses ◽  
Hiv 1

Identification of full-length transmitted HIV-1 genomes could be instrumental in HIV-1 pathogenesis, microbicide, and vaccine research by enabling the direct analysis of those viruses actually responsible for productive clinical infection. We show in 12 acutely infected subjects (9 clade B and 3 clade C) that complete HIV-1 genomes of transmitted/founder viruses can be inferred by single genome amplification and sequencing of plasma virion RNA. This allowed for the molecular cloning and biological analysis of transmitted/founder viruses and a comprehensive genome-wide assessment of the genetic imprint left on the evolving virus quasispecies by a composite of host selection pressures. Transmitted viruses encoded intact canonical genes (gag-pol-vif-vpr-tat-rev-vpu-env-nef) and replicated efficiently in primary human CD4+ T lymphocytes but much less so in monocyte-derived macrophages. Transmitted viruses were CD4 and CCR5 tropic and demonstrated concealment of coreceptor binding surfaces of the envelope bridging sheet and variable loop 3. 2 mo after infection, transmitted/founder viruses in three subjects were nearly completely replaced by viruses differing at two to five highly selected genomic loci; by 12–20 mo, viruses exhibited concentrated mutations at 17–34 discrete locations. These findings reveal viral properties associated with mucosal HIV-1 transmission and a limited set of rapidly evolving adaptive mutations driven primarily, but not exclusively, by early cytotoxic T cell responses.

scholarly journals Differential Induction of Interleukin-10 in Monocytes by HIV-1 Clade B and Clade C Tat Proteins

2010 ◽  
Vol 285 (24) ◽  
pp. 18319-18325 ◽  
Author(s):  
Justine K. Wong ◽  
Grant R. Campbell ◽  
Stephen A. Spector
Keyword(s):  
Interleukin 10 ◽  
Clade B ◽  
Clade C ◽  
Differential Induction ◽  
Hiv 1

scholarly journals HIV-1 Envelope Glycoprotein Trafficking and Viral Transmission

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 17
Author(s):  
Melissa Victoria Fernandez ◽  
Lwar N Naing ◽  
David A Scheiblin ◽  
Sherimay D Ablan ◽  
Jennifer A Simmons ◽  
...  
Keyword(s):  
T Cell ◽  
Envelope Glycoprotein ◽  
Viral Transmission ◽  
Virological Synapse ◽  
Glycoprotein Complex ◽  
Viral Spread ◽  
Clade B ◽  
Clade C ◽  
T Cell Lines ◽  
Hiv 1

HIV-1 encodes an envelope glycoprotein complex (Env) containing a long cytoplasmic tail (CT) harboring trafficking motifs implicated in Env incorporation into virions. Although the requirement for the Env CT in viral transmission is known, the precise mechanism by which Env is incorporated into nascent virions and localizes to the virological synapse remains poorly defined. To further elucidate the mechanism of Env trafficking, we examined three HIV-1 strains: the lab-adapted clade B strain, NL4-3, and a transmitted/founder (T/F) clade C virus, K3016, and a T/F clade B virus, CH077. The HIV-1 Env CT contains two invariant trafficking motifs: tyrosine endocytosis motif, Y712SPL, and C-terminal dileucine motif, LL855. Virion Env incorporation analysis revealed that Y712SPL is necessary for efficient Env incorporation, while LL855 is dispensable. Spreading infection kinetics were analyzed in various T-cell lines and primary human PBMCs; the results indicated that both endocytic motifs contribute to efficient viral spread in culture. Analysis of Env localization to the T-cell uropod, the portion of the plasma membrane that forms a virological synapse with uninfected cells, was found to be dependent on the Env CT and the Y712SPL motif. Cell-to-cell and cell-free transmission assays using T cells infected with HIV-1 bearing Y712A or LL855AA Env CT mutations are ongoing to establish a role for these motifs in both modes of viral transmission. These studies will significantly enhance our understanding of Env trafficking and viral transmission, providing insights into viral Env–host interactions in physiologically relevant cells.

scholarly journals Influence of HLA Class I and HLA-KIR Compound Genotypes on HIV-2 Infection and Markers of Disease Progression in a Manjako Community in West Africa

2010 ◽  
Vol 84 (16) ◽  
pp. 8202-8208 ◽  
Author(s):  
Louis-Marie Yindom ◽  
Aleksandra Leligdowicz ◽  
Maureen P. Martin ◽  
Xiaojiang Gao ◽  
Ying Qi ◽  
...  
Keyword(s):  
Immune Responses ◽  
Hla Class I ◽  
Gene Products ◽  
Viral Loads ◽  
Susceptibility To Infection ◽  
Clade B ◽  
Clade C ◽  
Unique Nature ◽  
First Time ◽  
Hiv 1

ABSTRACT Overall, the time to AIDS after HIV-2 infection is longer than with HIV-1, and many individuals infected with HIV-2 virus remain healthy throughout their lives. Multiple HLA and KIR gene products have been implicated in the control of HIV-1, but the effect of variation at these loci on HIV-2 disease is unknown. We show here for the first time that HLA-B*1503 is associated significantly with poor prognosis after HIV-2 infection and that HLA-B*0801 is associated with susceptibility to infection. Interestingly, previous data indicate that HLA-B*1503 is associated with low viral loads in HIV-1 clade B infection but has no significant effect on viral load in clade C infection. In general, alleles strongly associated with HIV-1 disease showed no effect in HIV-2 disease. These data emphasize the unique nature of the effects of HLA and HLA/KIR combinations on HIV-2 immune responses relative to HIV-1, which could be related to their distinct clinical course.

scholarly journals Regional Clustering of Shared Neutralization Determinants on Primary Isolates of Clade C Human Immunodeficiency Virus Type 1 from South Africa

2002 ◽  
Vol 76 (5) ◽  
pp. 2233-2244 ◽  
Author(s):  
Renata Bures ◽  
Lynn Morris ◽  
Carolyn Williamson ◽  
Gita Ramjee ◽  
Mark Deers ◽  
...  
Keyword(s):  
South Africa ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Serum Samples ◽  
Clade B ◽  
Immunodeficiency Virus ◽  
Clade C ◽  
Cross Neutralization ◽  
Hiv 1

ABSTRACT Clade C is one of the most prevalent genetic subtypes of human immunodeficiency virus type 1 (HIV-1) in the world today and one of the least studied with respect to neutralizing antibodies. Most information on HIV-1 serology as it relates to neutralization is derived from clade B. Clade C primary isolates of HIV-1 from South Africa and Malawi were shown here to resemble clade B isolates in their resistance to inhibition by soluble CD4 and their sensitivity to neutralization by human monoclonal antibody immunoglobulin G1b12 and, to a lesser extent, 2F5. Unlike clade B isolates, however, all 16 clade C isolates examined resisted neutralization by 2G12. Infection with clade C HIV-1 in a cohort of female sex workers in South Africa generated antibodies that neutralized the autologous clade C isolate and T-cell-line-adapted (TCLA) strains of clade B. Neutralization of clade B TCLA strains was much more sensitive to the presence of autologous gp120 V3 loop peptides compared to the neutralization of clade C isolates in most cases. Thus, the native structure of gp120 on primary isolates of clade C will likely pose a challenge for neutralizing antibody induction by candidate HIV-1 vaccines much the same as it has for clade B. The autologous neutralizing antibody response following primary infection with clade C HIV-1 in South Africa matured slowly, requiring at least 4 to 5 months to become detectable. Once detectable, extensive cross-neutralization of heterologous clade C isolates from South Africa was observed, suggesting an unusual degree of shared neutralization determinants at a regional level. This high frequency of cross-neutralization differed significantly from the ability of South African clade C serum samples to neutralize clade B isolates but did not differ significantly from results of other combinations of clade B and C reagents tested in checkerboard assays. Notably, two clade C serum samples obtained after less than 2 years of infection neutralized a broad spectrum of clade B and C isolates. Other individual serum samples showed a significant clade preference in their neutralizing activity. Our results suggest that clades B and C are each comprised of multiple neutralization serotypes, some of which are more clade specific than others. The clustering of shared neutralization determinants on clade C primary HIV-1 isolates from South Africa suggests that neutralizing antibodies induced by vaccines will have less epitope diversity to overcome at a regional level.

Identification and Characterization of Positively Selected Mutations in Nef of Four HIV-1 Major Subtypes from Los Alamos National Laboratory

2018 ◽  
Vol 16 (2) ◽  
pp. 130-142
Author(s):  
Elnaz Shadabi ◽  
Binhua Liang ◽  
Frank Plummer ◽  
Ma Luo
Keyword(s):  
National Laboratory ◽  
Alamos National Laboratory ◽  
Los Alamos ◽  
Evolutionary Patterns ◽  
Los Alamos National Laboratory ◽  
Immune Pressure ◽  
Subtype B ◽  
Clade B ◽  
Clade C ◽  
Hiv 1

Background:Human immunodeficiency virus-1 (HIV-1) mutates rapidly to escape host immune pressure. This results in the generation of positively selected mutations (PSM) throughout the viral genome. Escape mutations in Nef, one of the accessory proteins of HIV-1, which plays an important role in viral pathogenicity have previously been identified in several large cohort studies, but the evolution of PSMs overtime in various HIV-1 subtypes remains unknown.Methods:161 clade A1, 3093 clade B, 647 clade C and 115 clade D HIV-1 nef sequences were obtained from the HIV Database of Los Alamos National Laboratory and aligned using MEGA 6.0. The sequences from each clade were grouped based on the year of collection. Quasi analysis was used to identify PSMs and the number and locations of PSMs were compared among different subtypes.Results:PSMs for all four subtypes were distributed across the sequence of Nef, and conserved residues F90, W113, PxxPxR (a.a 72-77) remain unaltered overtime. The frequency of PSMs was stable among subtype B sequences but increased overtime for other subtypes. Phylogenetic analysis shows that sequences containing PSMs tend to cluster together at both inter and intra- subtype levels.Conclusion:Identification of PSMs and their changes overtime within various subtypes of HIV-1 is important in defining global viral evolutionary patterns that can provide insights for designing therapeutic strategies.

The frequency of HIV-I drug resistance mutations among treatment-naïve individuals at a tertiary care centre in south India

2009 ◽  
Vol 20 (8) ◽  
pp. 522-526 ◽  
Author(s):  
A J Kandathil ◽  
R Kannangai ◽  
O C Abraham ◽  
P Rupali ◽  
S A Pulimood ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Tertiary Care ◽  
Resistance Mutations ◽  
Tertiary Care Centre ◽  
Genotypic Resistance ◽  
Drug Resistance Mutations ◽  
Clade B ◽  
Clade C ◽  
Treatment Naïve ◽  
Hiv 1

Antiretroviral treatment (ART) use in India requires information on baseline drug resistance mutations and polymorphisms in the protease (Pr) and reverse transcriptase (RT) genes of HIV-1 strains from treatment-naïve individuals. We report resistance predictor mutations and polymorphisms in the Pr and the RT sequence of non-clade B HIV-1 strains from ART naïve individuals. The genotypic resistance assay was done on 93 treatment-naïve individuals. The sequences were analysed by Stanford HIV drug resistance data for genotypic drug resistance analysis and REGA HIV-1 subtyping tool. Phylogenetic tree was generated with MEGA 4 for quality control. Ninety-two strains belonged to clade C and one to clade A (A1). Amino acid substitutions were seen at positions associated with drug resistance in Pr gene – 10, 24, 74 (each 3%) and position 82 (11%). Substitutions were seen at positions 41 (1%), 100 (1%), 101 (6%), 103 (2%), 179 (6%) and 181 (1%) of the RT sequence known to confer drug resistance in clade B. Polymorphisms in HIV-1 pol gene among treatment-naïve individuals were similar when compared with previous data. One strain each had Y181C substitution, T74S and E35G substitutions in the Pr and one had A98G, K101R and L210FL substitutions in RT.

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