scholarly journals Determinants of Tetherin Antagonism in the Transmembrane Domain of the Human Immunodeficiency Virus Type 1 Vpu Protein

2010 ◽  
Vol 84 (24) ◽  
pp. 12958-12970 ◽  
Author(s):  
Raphaël Vigan ◽  
Stuart J. D. Neil
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Cell Surface ◽  
Human Immunodeficiency Virus Type ◽  
Transmembrane Domain ◽  
Human Tetherin ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Tetherin Antagonism

ABSTRACT Tetherin (BST2/CD317) potently restricts the particle release of human immunodeficiency virus type 1 (HIV-1) mutants defective in the accessory gene vpu. Vpu antagonizes tetherin activity and induces its cell surface downregulation and degradation in a manner dependent on the transmembrane (TM) domains of both proteins. We have carried out extensive mutagenesis of the HIV-1 NL4.3 Vpu TM domain to identify three amino acid positions, A14, W22, and, to a lesser extent, A18, that are required for tetherin antagonism. Despite the mutants localizing indistinguishably from the wild-type (wt) protein and maintaining the ability to multimerize, mutation of these positions rendered Vpu incapable of coimmunoprecipitating tetherin or mediating its cell surface downregulation. Interestingly, these amino acid positions are predicted to form one face of the Vpu transmembrane alpha helix and therefore potentially contribute to an interacting surface with the transmembrane domain of tetherin either directly or by modulating the conformation of Vpu oligomers. While the equivalent of W22 is invariant in HIV-1/SIVcpz Vpu proteins, the positions of A14 and A18 are highly conserved among Vpu alleles from HIV-1 groups M and N, but not those from group O or SIVcpz that lack human tetherin (huTetherin)-antagonizing activity, suggesting that they may have contributed to the adaption of HIV-1 to human tetherin.

scholarly journals Mutational Analysis of the Hydrophobic Tail of the Human Immunodeficiency Virus Type 1 p6Gag Protein Produces a Mutant That Fails To Package Its Envelope Protein

1999 ◽  
Vol 73 (1) ◽  
pp. 19-28 ◽  
Author(s):  
David E. Ott ◽  
Elena N. Chertova ◽  
Laura K. Busch ◽  
Lori V. Coren ◽  
Tracy D. Gagliardi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Wild Type ◽  
Immunodeficiency Virus ◽  
Hydrophobic Tail ◽  
Carboxyl Terminal ◽  
Hiv 1

ABSTRACT The p6Gag protein of human immunodeficiency virus type 1 (HIV-1) is produced as the carboxyl-terminal sequence within the Gag polyprotein. The amino acid composition of this protein is high in hydrophilic and polar residues except for a patch of relatively hydrophobic amino acids found in the carboxyl-terminal 16 amino acids. Internal cleavage of p6Gag between Y36 and P37, apparently by the HIV-1 protease, removes this hydrophobic tail region from approximately 30% of the mature p6Gag proteins in HIV-1MN. To investigate the importance of this cleavage and the hydrophobic nature of this portion of p6Gag, site-directed mutations were made at the minor protease cleavage site and within the hydrophobic tail. The results showed that all of the single-amino-acid-replacement mutants exhibited either reduced or undetectable cleavage at the site yet almost all were nearly as infectious as wild-type virus, demonstrating that processing at this site is not important for viral replication. However, one exception, Y36F, was 300-fold as infectious the wild type. In contrast to the single-substitution mutants, a virus with two substitutions in this region of p6Gag, Y36S-L41P, could not infect susceptible cells. Protein analysis showed that while the processing of the Gag precursor was normal, the double mutant did not incorporate Env into virus particles. This mutant could be complemented with surface glycoproteins from vesicular stomatitis virus and murine leukemia virus, showing that the inability to incorporate Env was the lethal defect for the Y36S-L41P virus. However, this mutant was not rescued by an HIV-1 Env with a truncated gp41TM cytoplasmic domain, showing that it is phenotypically different from the previously described MA mutants that do not incorporate their full-length Env proteins. Cotransfection experiments with Y36S-L41P and wild-type proviral DNAs revealed that the mutant Gag dominantly blocked the incorporation of Env by wild-type Gag. These results show that the Y36S-L41P p6Gag mutation dramatically blocks the incorporation of HIV-1 Env, presumably acting late in assembly and early during budding.

scholarly journals Matrix and Envelope Coevolution Revealed in a Patient Monitored since Primary Infection with Human Immunodeficiency Virus Type 1

2009 ◽  
Vol 83 (19) ◽  
pp. 9875-9889 ◽  
Author(s):  
Elodie Beaumont ◽  
Daniela Vendrame ◽  
Bernard Verrier ◽  
Emmanuelle Roch ◽  
François Biron ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Matrix Protein ◽  
Immunodeficiency Virus ◽  
The Matrix ◽  
Hiv 1

ABSTRACT Lentiviruses, including human immunodeficiency virus type 1 (HIV-1), typically encode envelope glycoproteins (Env) with long cytoplasmic tails (CTs). The strong conservation of CT length in primary isolates of HIV-1 suggests that this factor plays a key role in viral replication and persistence in infected patients. However, we report here the emergence and dominance of a primary HIV-1 variant carrying a natural 20-amino-acid truncation of the CT in vivo. We demonstrated that this truncation was deleterious for viral replication in cell culture. We then identified a compensatory amino acid substitution in the matrix protein that reversed the negative effects of CT truncation. The loss or rescue of infectivity depended on the level of Env incorporation into virus particles. Interestingly, we found that a virus mutant with defective Env incorporation was able to spread by cell-to-cell transfer. The effects on viral infectivity of compensation between the CT and the matrix protein have been suggested by in vitro studies based on T-cell laboratory-adapted virus mutants, but we provide here the first demonstration of the natural occurrence of similar mechanisms in an infected patient. Our findings provide insight into the potential of HIV-1 to evolve in vivo and its ability to overcome major structural alterations.

scholarly journals Role of Cell Surface Glycosaminoglycans of Human T Cells in Human Immunodeficiency Virus Type-1 (HIV-1) Infection

1996 ◽  
Vol 40 (11) ◽  
pp. 827-835 ◽  
Author(s):  
Yukako Ohshiro ◽  
Tsutomu Murakami ◽  
Kazuhiro Matsuda ◽  
Kiyoshi Nishioka ◽  
Keiichi Yoshida ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Cell Surface ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Human T Cells ◽  
Immunodeficiency Virus ◽  
Hiv 1

scholarly journals Human Immunodeficiency Virus Type 1 Derived from Cocultures of Immature Dendritic Cells with Autologous T Cells Carries T-Cell-Specific Molecules on Its Surface and Is Highly Infectious

1999 ◽  
Vol 73 (4) ◽  
pp. 3449-3454 ◽  
Author(s):  
Ines Frank ◽  
Laco Kacani ◽  
Heribert Stoiber ◽  
Hella Stössel ◽  
Martin Spruth ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Surface ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT During the budding process, human immunodeficiency virus type 1 (HIV-1) acquires cell surface molecules; thus, the viral surface of HIV-1 reflects the antigenic pattern of the host cell. To determine the source of HIV-1 released from cocultures of dendritic cells (DC) with T cells, immature DC (imDC), mature DC (mDC), T cells, and their cocultures were infected with different HIV-1 isolates. The macrophage-tropic HIV-1 isolate Ba-L allowed viral replication in both imDC and mDC, whereas the T-cell-line-tropic primary isolate PI21 replicated in mDC only. By a virus capture assay, HIV-1 was shown to carry a T-cell- or DC-specific cell surface pattern after production by T cells or DC, respectively. Upon cocultivation of HIV-1-pulsed DC with T cells, HIV-1 exclusively displayed a typical T-cell pattern. Additionally, functional analysis revealed that HIV-1 released from imDC–T-cell cocultures was more infectious than HIV-1 derived from mDC–T-cell cocultures and from cultures of DC, T cells, or peripheral blood mononuclear cells alone. Therefore, we conclude that the interaction of HIV-1-pulsed imDC with T cells in vivo might generate highly infectious virus which primarily originates from T cells.

scholarly journals Anti-Human Immunodeficiency Virus Type 1 Activity of Novel 6-Substituted 1-Benzyl-3-(3,5-Dimethylbenzyl)Uracil Derivatives

2012 ◽  
Vol 56 (5) ◽  
pp. 2581-2589 ◽  
Author(s):  
Paula Ordonez ◽  
Takayuki Hamasaki ◽  
Yohei Isono ◽  
Norikazu Sakakibara ◽  
Masahiro Ikejiri ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Rnase H ◽  
Uracil Derivatives ◽  
Immunodeficiency Virus ◽  
Precise Role ◽  
Hiv 1

ABSTRACTNonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs) are important components of current combination therapies for human immunodeficiency virus type 1 (HIV-1) infection. In screening of chemical libraries, we found 6-azido-1-benzyl-3-(3,5-dimethylbenzyl)uracil (AzBBU) and 6-amino-1-benzyl-3-(3,5-dimethylbenzyl)uracil (AmBBU) to be highly active and selective inhibitors of HIV-1 replicationin vitro. To determine the resistance profiles of these compounds, we conducted a long-term culture of HIV-1-infected MT-4 cells with escalating concentrations of each compound. After serial passages of the infected cells, escape viruses were obtained, and they were more than 500-fold resistant to the uracil derivatives compared to the wild type. Sequence analysis was conducted for RT of the escape viruses at passages 12 and 24. The amino acid mutation Y181C in the polymerase domain of RT was detected for all escape viruses. Docking studies using the crystal structure of RT showed that AmBBU requires the amino acid residues Leu100, Val106, Tyr181, and Trp229 for exerting its inhibitory effect on HIV-1. Four additional amino acid changes (K451R, R461K, T468P, and D471N) were identified in the RNase H domain of RT; however, their precise role in the acquisition of resistance is still unclear. In conclusion, the initial mutation Y181C seems sufficient for the acquisition of resistance to the uracil derivatives AzBBU and AmBBU. Further studies are required to determine the precise role of each mutation in the acquisition of HIV-1 resistance.

scholarly journals Impact of Human Immunodeficiency Virus Type 1 gp41 Amino Acid Substitutions Selected during Enfuvirtide Treatment on gp41 Binding and Antiviral Potency of Enfuvirtide In Vitro

2005 ◽  
Vol 79 (19) ◽  
pp. 12447-12454 ◽  
Author(s):  
M. Mink ◽  
S. M. Mosier ◽  
S. Janumpalli ◽  
D. Davison ◽  
L. Jin ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Binding Affinity ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Fusion Inhibitor ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Enfuvirtide (ENF), a novel human immunodeficiency virus type 1 (HIV-1) fusion inhibitor, has potent antiviral activity against HIV-1 both in vitro and in vivo. Resistance to ENF observed after in vitro passaging was associated with changes in a three-amino-acid (aa) motif, GIV, at positions 36 to 38 of gp41. Patients with ongoing viral replication while receiving ENF during clinical trials acquired substitutions within gp41 aa 36 to 45 in the first heptad repeat (HR-1) of gp41 in both population-based plasma virus sequences and proviral DNA sequences from isolates showing reduced susceptibilities to ENF. To investigate their impact on ENF susceptibility, substitutions were introduced into a modified pNL4-3 strain by site-directed mutagenesis, and the susceptibilities of mutant viruses and patient-derived isolates to ENF were tested. In general, susceptibility decreases for single substitutions were lower than those for double substitutions, and the levels of ENF resistance seen for clinical isolates were higher than those observed for the site-directed mutant viruses. The mechanism of ENF resistance was explored for a subset of the substitutions by expressing them in the context of a maltose binding protein chimera containing a portion of the gp41 ectodomain and measuring their binding affinity to fluorescein-labeled ENF. Changes in binding affinity for the mutant gp41 fusion proteins correlated with the ENF susceptibilities of viruses containing the same substitutions. The combined results support the key role of gp41 aa 36 to 45 in the development of resistance to ENF and illustrate that additional envelope regions contribute to the ENF susceptibility of fusion inhibitor-naïve viruses and resistance to ENF.

scholarly journals Determinants of Syncytium Formation in Microglia by Human Immunodeficiency Virus Type 1: Role of the V1/V2 Domains

2000 ◽  
Vol 74 (2) ◽  
pp. 693-701 ◽  
Author(s):  
Joseph T. C. Shieh ◽  
Julio Martín ◽  
Gordon Baltuch ◽  
Michael H. Malim ◽  
Francisco González-Scarano
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Syncytium Formation ◽  
Single Amino Acid ◽  
Single Amino Acid Change ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Microglia are the main reservoir for human immunodeficiency virus type 1 (HIV-1) in the central nervous system (CNS), and multinucleated giant cells, the result of fusion of HIV-1-infected microglia and brain macrophages, are the neuropathologic hallmark of HIV dementia. One potential explanation for the formation of syncytia is viral adaptation for these CD4+ CNS cells. HIV-1BORI-15, a virus adapted to growth in microglia by sequential passage in vitro, mediates high levels of fusion and replicates more efficiently in microglia and monocyte-derived-macrophages than its unpassaged parent (J. M. Strizki, A. V. Albright, H. Sheng, M. O'Connor, L. Perrin, and F. Gonzalez-Scarano, J. Virol. 70:7654–7662, 1996). Since the interaction between the viral envelope glycoprotein and CD4 and the chemokine receptor mediates fusion and plays a key role in tropism, we have analyzed the HIV-1BORI-15 env as a fusogen and in recombinant and pseudotyped viruses. Its syncytium-forming phenotype is not the result of a switch in coreceptor use but rather of the HIV-1BORI-15envelope-mediated fusion of CD4+CCR5+ cells with greater efficiency than that of its parental strain, either by itself or in the context of a recombinant virus. Genetic analysis indicated that the syncytium-forming phenotype was due to four discrete amino acid differences in V1/V2, with a single-amino-acid change between the parent and the adapted virus (E153G) responsible for the majority of the effect. Additionally, HIV-1BORI-15 env-pseudotyped viruses were less sensitive to decreases in the levels of CD4 on transfected 293T cells, leading to the hypothesis that the differences in V1/V2 alter the interaction between this envelope and CD4 or CCR5, or both. In sum, the characterization of the envelope of HIV-1BORI-15, a highly fusogenic glycoprotein with genetic determinants in V1/V2, may lead to a better understanding of the relationship between HIV replication and syncytium formation in the CNS and of the importance of this region of gp120 in the interaction with CD4 and CCR5.

scholarly journals Human Immunodeficiency Virus Type 1 Resistance to the Small Molecule Maturation Inhibitor 3-O-(3′,3′-Dimethylsuccinyl)-Betulinic Acid Is Conferred by a Variety of Single Amino Acid Substitutions at the CA-SP1 Cleavage Site in Gag

2006 ◽  
Vol 80 (24) ◽  
pp. 12095-12101 ◽  
Author(s):  
Jing Zhou ◽  
Chin Ho Chen ◽  
Christopher Aiken
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Betulinic Acid ◽  
Cleavage Site ◽  
Amino Acid Substitutions ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The compound 3-O-(3′,3′-dimethylsuccinyl)-betulinic acid (DSB) potently and specifically inhibits human immunodeficiency virus type 1 (HIV-1) replication by delaying the cleavage of the CA-SP1 junction in Gag, leading to impaired maturation of the viral core. In this study, we investigated HIV-1 resistance to DSB by analyzing HIV-1 mutants encoding a variety of individual amino acid substitutions in the CA-SP1 cleavage site. Three of the substitutions were lethal to HIV-1 replication owing to a deleterious effect on particle assembly. The remaining mutants exhibited a range of replication efficiencies; however, each mutant was capable of replicating in the presence of concentrations of DSB that effectively inhibited wild-type HIV-1. Mutations conferring resistance to DSB also led to impaired binding of the compound to immature HIV-1 virions and loss of DSB-mediated inhibition of cleavage of Gag. Surprisingly, two of the DSB-resistant mutants retained an intermediate ability to bind the compound, suggesting that binding of DSB to immature HIV-1 particles may not be sufficient for antiviral activity. Overall, our results indicate that Gag amino acids L363 and A364 are critical for inhibition of HIV-1 replication by DSB and suggest that these residues form key contacts with the drug in the context of the assembling HIV-1 particle. These results have implications for the design of and screening for novel inhibitors of HIV-1 maturation.

scholarly journals Genetic Characterization of Human Immunodeficiency Virus Type 1 in Elite Controllers: Lack of Gross Genetic Defects or Common Amino Acid Changes

2008 ◽  
Vol 82 (17) ◽  
pp. 8422-8430 ◽  
Author(s):  
Toshiyuki Miura ◽  
Mark A. Brockman ◽  
Chanson J. Brumme ◽  
Zabrina L. Brumme ◽  
Jonathan M. Carlson ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Genetic Defects ◽  
Elite Controllers ◽  
Significant Difference ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Despite reports of viral genetic defects in persons who control human immunodeficiency virus type 1 (HIV-1) in the absence of antiviral therapy, the extent to which such defects contribute to the long-term containment of viremia is not known. Most previous studies examining for such defects have involved small numbers of subjects, primarily focused on subjects expressing HLA-B57, or have examined single viral genes, and they have focused on cellular proviral DNA rather than plasma viral RNA sequences. Here, we attempted viral sequencing from 95 HIV-1 elite controllers (EC) who maintained plasma viral loads of <50 RNA copies/ml in the absence of therapy, the majority of whom did not express HLA-B57. HIV-1 gene fragments were obtained from 94% (89/95) of the EC, and plasma viral sequences were obtained from 78% (61/78), the latter indicating the presence of replicating virus in the majority of EC. Of 63 persons for whom nef was sequenced, only three cases of nef deletions were identified, and gross genetic defects were rarely observed in other HIV-1 coding genes. In a codon-by-codon comparison between EC and persons with progressive infection, correcting for HLA bias and coevolving secondary mutations, a significant difference was observed at only three codons in Gag, all three of which represented the historic population consensus amino acid at the time of infection. These results indicate that the spontaneous control of HIV replication is not attributable to shared viral genetic defects or shared viral polymorphisms.

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