A Single Amino Acid in Human APOBEC3F Alters Susceptibility to HIV-1 Vif

ABSTRACTAntibodies (Abs) specific for the V3 loop of the HIV-1 gp120 envelope neutralize most tier 1 and many tier 2 viruses and are present in essentially all HIV-infected individuals as well as immunized humans and animals. Vaccine-induced V3 Abs are associated with reduced HIV infection rates in humans and affect the nature of transmitted viruses in infected vaccinees, despite the fact that V3 is often occluded in the envelope trimer. Here, we link structural and experimental data showing how conformational alterations of the envelope trimer render viruses exceptionally sensitive to V3 Abs. The experiments interrogated the neutralization sensitivity of pseudoviruses with single amino acid mutations in various regions of gp120 that were predicted to alter packing of the V3 loop in the Env trimer. The results indicate that the V3 loop is metastable in the envelope trimer on the virion surface, flickering between states in which V3 is either occluded or available for binding to chemokine receptors (leading to infection) and to V3 Abs (leading to virus neutralization). The spring-loaded V3 in the envelope trimer is easily released by disruption of the stability of the V3 pocket in the unliganded trimer or disruption of favorable V3/pocket interactions. Formation of the V3 pocket requires appropriate positioning of the V1V2 domain, which is, in turn, dependent on the conformation of the bridging sheet and on the stability of the V1V2 B-C strand-connecting loop.IMPORTANCEThe levels of antibodies to the third variable region (V3) of the HIV envelope protein correlate with reduced HIV infection rates. Previous studies showed that V3 is often occluded, as it sits in a pocket of the envelope trimer on the surface of virions; however, the trimer is flexible, allowing occluded portions of the envelope (like V3) to flicker into an exposed position that binds antibodies. Here we provide a systematic interrogation of mechanisms by which single amino acid changes in various regions of gp120 (i) render viruses sensitive to neutralization by V3 antibodies, (ii) result in altered packing of the V3 loop, and (iii) activate an open conformation that exposes V3 to the effects of V3 Abs. Taken together, these and previous studies explain how V3 antibodies can protect against HIV-1 infection and why they should be one of the targets of vaccine-induced antibodies.

Download Full-text

Mechanism of Darunavir (DRV)’s High Genetic Barrier to HIV-1 Resistance: A Key V32I Substitution in Protease Rarely Occurs, but Once It Occurs, It Predisposes HIV-1 To Develop DRV Resistance

mBio ◽

10.1128/mbio.02425-17 ◽

2018 ◽

Vol 9 (2) ◽

Cited By ~ 12

Author(s):

Manabu Aoki ◽

Debananda Das ◽

Hironori Hayashi ◽

Hiromi Aoki-Ogata ◽

Yuki Takamatsu ◽

...

Keyword(s):

Drug Resistance ◽

Amino Acid ◽

Critical Role ◽

Viral Fitness ◽

Single Amino Acid ◽

Amino Acid Substitutions ◽

Wild Type ◽

Genetic Barrier ◽

High Level ◽

Hiv 1

ABSTRACTDarunavir (DRV) has bimodal activity against HIV-1 protease, enzymatic inhibition and protease dimerization inhibition, and has an extremely high genetic barrier against development of drug resistance. We previously generated a highly DRV-resistant HIV-1 variant (HIVDRVRP51). We also reported that four amino acid substitutions (V32I, L33F, I54M, and I84V) identified in the protease of HIVDRVRP51are largely responsible for its high-level resistance to DRV. Here, we attempted to elucidate the role of each of the four amino acid substitutions in the development of DRV resistance. We found that V32I is a key substitution, which rarely occurs, but once it occurs, it predisposes HIV-1 to develop high-level DRV resistance. When two infectious recombinant HIV-1 clones carrying I54M and I84V (rHIVI54Mand rHIVI84V, respectively) were selected in the presence of DRV, V32I emerged, and the virus rapidly developed high-level DRV resistance. rHIVV32Ialso developed high-level DRV resistance. However, wild-type HIVNL4-3(rHIVWT) failed to acquire V32I and did not develop DRV resistance. Compared to rHIVWT, rHIVV32Iwas highly susceptible to DRV and had significantly reduced fitness, explaining why V32I did not emerge upon selection of rHIVWTwith DRV. When the only substitution is at residue 32, structural analysis revealed much stronger van der Waals interactions between DRV and I-32 than between DRV and V-32. These results suggest that V32I is a critical amino acid substitution in multiple pathways toward HIV-1’s DRV resistance development and elucidate, at least in part, a mechanism of DRV’s high genetic barrier to development of drug resistance. The results also show that attention should be paid to the initiation or continuation of DRV-containing regimens in people with HIV-1 containing the V32I substitution.IMPORTANCEDarunavir (DRV) is the only protease inhibitor (PI) recommended as a first-line therapeutic and represents the most widely used PI for treating HIV-1-infected individuals. DRV possesses a high genetic barrier to development of HIV-1’s drug resistance. However, the mechanism(s) of the DRV’s high genetic barrier remains unclear. Here, we show that the preexistence of certain single amino acid substitutions such as V32I, I54M, A71V, and I84V in HIV-1 protease facilitates the development of high-level DRV resistance. Interestingly, allin vitro-selected highly DRV-resistant HIV-1 variants acquired V32I but never emerged in wild-type HIV (HIVWT), and V32I itself rendered HIV-1 more sensitive to DRV and reduced viral fitness compared to HIVWT, strongly suggesting that the emergence of V32I plays a critical role in the development of HIV-1’s resistance to DRV. Our results would be of benefit in the treatment of HIV-1-infected patients receiving DRV-containing regimens.

Download Full-text

Single Amino Acid Change in Tat Determines the Different Rates of Replication of Two Sequential HIV-1 Isolates

Virology ◽

10.1006/viro.1993.1394 ◽

1993 ◽

Vol 195 (2) ◽

pp. 441-447 ◽

Cited By ~ 13

Author(s):

Muriel Leguern ◽

Tatsuo Shioda ◽

Jay A. Levy ◽

Cecilia Cheng Mayer

Keyword(s):

Amino Acid ◽

Amino Acid Change ◽

Single Amino Acid ◽

Single Amino Acid Change ◽

Hiv 1

Download Full-text

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

Journal of Virology ◽

10.1128/jvi.74.2.693-701.2000 ◽

2000 ◽

Vol 74 (2) ◽

pp. 693-701 ◽

Cited By ~ 35

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.

Download Full-text

Thymidine Analogue Excision and Discrimination Modulated by Mutational Complexes Including Single Amino Acid Deletions of Asp-67 or Thr-69 in HIV-1 Reverse Transcriptase

Journal of Biological Chemistry ◽

10.1074/jbc.m111.226100 ◽

2011 ◽

Vol 286 (23) ◽

pp. 20615-20624 ◽

Cited By ~ 12

Author(s):

Mónica Kisic ◽

Tania Matamoros ◽

María Nevot ◽

Jesús Mendieta ◽

Javier Martinez-Picado ◽

...

Keyword(s):

Amino Acid ◽

Reverse Transcriptase ◽

Single Amino Acid ◽

Thymidine Analogue ◽

Hiv 1

Download Full-text

Antagonism of BST-2/Tetherin Is a Conserved Function of the Env Glycoprotein of Primary HIV-2 Isolates

Journal of Virology ◽

10.1128/jvi.01451-16 ◽

2016 ◽

Vol 90 (24) ◽

pp. 11062-11074 ◽

Cited By ~ 9

Author(s):

Chia-Yen Chen ◽

Masashi Shingai ◽

Sarah Welbourn ◽

Malcolm A. Martin ◽

Pedro Borrego ◽

...

Keyword(s):

Amino Acid ◽

Amino Acid Change ◽

Mixed Population ◽

Single Amino Acid ◽

Amino Acid Difference ◽

Virus Release ◽

Host Restriction ◽

Single Amino Acid Change ◽

Hiv 1 ◽

Env Glycoprotein

ABSTRACTAlthough HIV-2 does not encode avpugene, the ability to antagonize bone marrow stromal antigen 2 (BST-2) is conserved in some HIV-2 isolates, where it is controlled by the Env glycoprotein. We previously reported that a single-amino-acid difference between the laboratory-adapted ROD10 and ROD14 Envs controlled the enhancement of virus release (referred to here as Vpu-like) activity. Here, we investigated how conserved the Vpu-like activity is in primary HIV-2 isolates. We found that half of the 34 tested primary HIV-2 Env isolates obtained from 7 different patients enhanced virus release. Interestingly, most HIV-2 patients harbored a mixed population of viruses containing or lacking Vpu-like activity. Vpu-like activity and Envelope functionality varied significantly among Env isolates; however, there was no direct correlation between these two functions, suggesting they evolved independently. In comparing the Env sequences from one HIV-2 patient, we found that similar to the ROD10/ROD14 Envs, a single-amino-acid change (T568I) in the ectodomain of the TM subunit was sufficient to confer Vpu-like activity to an inactive Env variant. Surprisingly, however, absence of Vpu-like activity was not correlated with absence of BST-2 interaction. Taken together, our data suggest that maintaining the ability to antagonize BST-2 is of functional relevance not only to HIV-1 but also to HIV-2 as well. Our data show that as with Vpu, binding of HIV-2 Env to BST-2 is important but not sufficient for antagonism. Finally, as observed previously, the Vpu-like activity in HIV-2 Env can be controlled by single-residue changes in the TM subunit.IMPORTANCELentiviruses such as HIV-1 and HIV-2 encode accessory proteins whose function is to overcome host restriction mechanisms. Vpu is a well-studied HIV-1 accessory protein that enhances virus release by antagonizing the host restriction factor BST-2. HIV-2 does not encode avpugene. Instead, the HIV-2 Env glycoprotein was found to antagonize BST-2 in some isolates. Here, we cloned multiple Env sequences from 7 HIV-2-infected patients and found that about half were able to antagonize BST-2. Importantly, most HIV-2 patients harbored a mixed population of viruses containing or lacking the ability to antagonize BST-2. In fact, in comparing Env sequences from one patient combined with site-directed mutagenesis, we were able to restore BST-2 antagonism to an inactive Env protein by a single-amino-acid change. Our data suggest that targeting BST-2 by HIV-2 Env is a dynamic process that can be regulated by simple changes in the Env sequence.

Download Full-text

Species-specific valid ternary interactions of HIV-1 Env-gp120, CD4, and CCR5 as revealed by an adaptive single-amino acid substitution at the V3 loop tip

Journal of Virology ◽

10.1128/jvi.02177-20 ◽

2021 ◽

Author(s):

Takaaki Koma ◽

Masaru Yokoyama ◽

Osamu Kotani ◽

Naoya Doi ◽

Nina Nakanishi ◽

...

Keyword(s):

Amino Acid ◽

Molecular Interactions ◽

Md Simulations ◽

Single Amino Acid ◽

V3 Loop ◽

Cell Tropism ◽

Binding Ability ◽

Ternary Interactions ◽

Species Specific ◽

Hiv 1

Molecular interactions of the variable envelope gp120 subunit of HIV-1 with two cellular receptors are the first step of viral infection, thereby playing pivotal roles in determining viral infectivity and cell tropism. However, the underlying regulatory mechanisms for interactions under gp120 spontaneous variations largely remain unknown. Here we show an allosteric mechanism in which a single gp120 mutation remotely controls the ternary interactions between gp120 and its receptors for the switch of viral cell tropism. Virological analyses showed that a G310R substitution at the tip of the gp120 V3 loop selectively abolished the viral replication ability in human cells, despite evoking enhancement of viral replication in macaque cells. Molecular dynamics (MD) simulations predicted that the G310R substitution at a site away from the CD4 interaction site selectively impeded the binding ability of gp120 to human CD4. Consistently, virions with the G310R substitution exhibited a reduced binding ability to human lymphocyte cells. Furthermore, the G310R substitution influenced the gp120-CCR5 interaction in a CCR5-type dependent manner as assessed by MD simulations and an infectivity assay using exogenously expressed CCR5s. Interestingly, an I198M mutation in human CCR5 restored the infectivity of the G310R virus in human cells. Finally, MD simulation predicted amino acid interplays that physically connect the V3 loop and gp120 elements for the CD4 and CCR5 interactions. Collectively, these results suggest that the V3 loop tip is a cis-allosteric regulator that remotely controls intra- and inter-molecular interactions of HIV-1 gp120 for balancing ternary interactions with CD4 and CCR5. IMPORTANCE Understanding molecular bases for viral entry into cells leads to the elucidation of one of major viral survival strategies, and thus to the development of new effective antiviral measures. As experimentally shown recently, HIV-1 is highly mutable and adaptable in growth-restrictive cells such as those of macaque origin. HIV-1 initiates its infection by sequential interactions of Env-gp120 with two cell surface receptors, CD4 and CCR5. A recent epoch-making structural study has disclosed that CD4-induced conformation of gp120 is stabilized upon binding of CCR5 to the CD4-gp120 complex, whereas its biological significance remains totally unknown. Here, from a series of mutations found in our extensive studies, we identified a single-amino acid adaptive mutation at the V3 loop tip of Env-gp120 critical for its interaction with both CD4 and CCR5 in a host cell species-specific way. This remarkable finding would certainly provoke and accelerate studies to precisely clarify the HIV-1 entry mechanism.

Download Full-text

S-1153 Inhibits Replication of Known Drug-Resistant Strains of Human Immunodeficiency Virus Type 1

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.42.6.1340 ◽

1998 ◽

Vol 42 (6) ◽

pp. 1340-1345 ◽

Cited By ~ 82

Author(s):

Tamio Fujiwara ◽

Akihiko Sato ◽

Mohamed El-Farrash ◽

Shigeru Miki ◽

Kenji Abe ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Amino Acid ◽

Reverse Transcriptase ◽

Single Amino Acid ◽

Amino Acid Substitutions ◽

Reverse Transcriptase Inhibitors ◽

Human T Cell ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT S-1153 is a new imidazole compound that inhibits human immunodeficiency virus (HIV) type 1 (HIV-1) replication by acting as a nonnucleoside reverse transcriptase inhibitor (NNRTI). This compound inhibits replication of HIV-1 strains that are resistant to nucleoside and nonnucleoside reverse transcriptase inhibitors. S-1153 has a 50% effective concentration in the range of 0.3 to 7 ng/ml for strains with single amino acid substitutions that cause NNRTI resistance, including the Y181C mutant, and also has potent activity against clinical isolates. The emergence of S-1153-resistant variants is slower than that for nevirapine, and S-1153-resistant variants contained at least two amino acid substitutions, including F227L or L234I. S-1153-resistant variants are still sensitive to the nucleoside reverse transcriptase inhibitors zidovudine (AZT) and lamivudine. In a mouse and MT-4 (human T-cell line) in vivo HIV replication model, S-1153 and AZT administered orally showed a marked synergy for the inhibition of HIV-1 replication. S-1153 shows a significant accumulation in lymph nodes, where most HIV-1 infection is thought to occur. S-1153 may be an appropriate candidate for two- to three-drug combination therapy for HIV infection.

Download Full-text