A Global Neutralization Resistance Phenotype of Human Immunodeficiency Virus Type 1 Is Determined by Distinct Mechanisms Mediating Enhanced Infectivity and Conformational Change of the Envelope Complex

ABSTRACT We have described previously genetic characterization of neutralization-resistant, high-infectivity, and neutralization-sensitive, low-infectivity mutants of human immunodeficiency virus type 1 (HIV-1) MN envelope. The distinct phenotypes of these clones are attributable to six mutations affecting functional interactions between the gp120 C4-V5 regions and the gp41 leucine zipper. In the present study we examined mechanisms responsible for the phenotypic differences between these envelopes using neutralization and immunofluorescence assays (IFA). Most monoclonal antibodies (MAbs) tested against gp120 epitopes (V3, CD4 binding site, and CD4-induced) were 20 to 100 times more efficient at neutralizing pseudovirus expressing sensitive rather than resistant envelope. By IFA cells expressing neutralization sensitive envelope bound MAbs to gp120 epitopes more, but gp41 epitopes less, than neutralization-resistant envelope. This binding difference appeared to reflect conformational change, since it did not correlate with the level of protein expression or gp120-gp41 dissociation. This conformational change was mostly attributable to one mutation, L544P, which contributes to neutralization resistance but not to infectivity enhancement. The V420I mutation, which contributes a major effect to both high infectivity and neutralization resistance, had no apparent effect on conformation. Notably, a conformation-dependent V3 neutralization epitope remained sensitive to neutralization and accessible to binding by MAbs on neutralization-resistant HIV-1 envelope. Sensitivity to sCD4 did not distinguish the clones, suggesting that the phenotypes may be related to post-CD4-binding effects. The results demonstrate that neutralization resistance can be determined by distinguishable effects of mutations, which cause changes in envelope conformation and/or function(s) related to infectivity. A conformation-dependent V3 epitope may be an important target for neutralization of resistant strains of HIV-1.

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Concordant Modulation of Neutralization Resistance and High Infectivity of the Primary Human Immunodeficiency Virus Type 1 MN Strain and Definition of a Potential gp41 Binding Site in gp120

Journal of Virology ◽

10.1128/jvi.77.1.560-570.2003 ◽

2003 ◽

Vol 77 (1) ◽

pp. 560-570 ◽

Cited By ~ 23

Author(s):

Maria Leavitt ◽

Eun Ju Park ◽

Igor A. Sidorov ◽

Dimiter S. Dimitrov ◽

Gerald V. Quinnan,

Keyword(s):

Human Immunodeficiency Virus ◽

Binding Site ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Binding Sites ◽

Leucine Zipper ◽

Immunodeficiency Virus ◽

Hiv 1 ◽

High Infectivity

ABSTRACT Efforts to develop a vaccine against human immunodeficiency virus type 1 (HIV-1) are complicated by resistance of virus to neutralization. The neutralization resistance phenotype of HIV-1 has been linked to high infectivity. We studied the mechanisms determining this phenotype using clones of the T-cell-line-adapted (TCLA) MN strain (MN-TCLA) and the neutralization-resistant, primary MN strain (MN-P). Mutations in the amino- and carboxy-terminal halves of gp120 and the carboxy terminus of gp41 contributed to the neutralization resistance, high-infectivity phenotype but depended upon sequences in the leucine zipper (LZ) domain of gp41. Among 23 clones constructed to map the contributing mutations, there was a very strong correlation between infectivity and neutralization resistance (R 2 = 0.81; P < 0.0001). Mutations that distinguished the gp120s of MN-P and MN-TCLA clones were clustered in or near the CD4 and coreceptor binding sites and in regions distant from those binding sites. To test the hypothesis that some of these distant mutations may interact with gp41, we determined which of them contributed to high infectivity and whether those mutations modulated gp120-gp41 association in the context of MN-P LZ sequences. In one clone, six mutations in the amino terminus of gp120, at least four of which clustered closely on the inner domain, modulated infectivity. This clone had a gp120-gp41 association phenotype like MN-P: in comparison to MN-TCLA, spontaneous dissociation was low, and dissociation induced by soluble CD4 binding was high. These results identify a region of the gp120 inner domain that may be a binding site for gp41. Our studies clarify mechanisms of primary virus neutralization resistance.

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Human Immunodeficiency Virus Type 1 Nucleocapsid p1 Confers ESCRT Pathway Dependence

Journal of Virology ◽

10.1128/jvi.00035-10 ◽

2010 ◽

Vol 84 (13) ◽

pp. 6590-6597 ◽

Cited By ~ 22

Author(s):

Elena Popova ◽

Sergei Popov ◽

Heinrich G. Göttlinger

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Leucine Zipper ◽

Particle Production ◽

Dominant Negative ◽

Dimerization Domain ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT To facilitate the release of infectious progeny virions, human immunodeficiency virus type 1 (HIV-1) exploits the Endosomal Sorting Complex Required for Transport (ESCRT) pathway by engaging Tsg101 and ALIX through late assembly (L) domains in the C-terminal p6 domain of Gag. However, the L domains in p6 are known to be dispensable for efficient particle production by certain HIV-1 Gag constructs that have the nucleocapsid (NC) domain replaced by a foreign dimerization domain to substitute for the assembly function of NC. We now show that one such L domain-independent HIV-1 Gag construct (termed ZWT) that has NC-p1-p6 replaced by a leucine zipper domain is resistant to dominant-negative inhibitors of the ESCRT pathway that block HIV-1 particle production. However, ZWT became dependent on the presence of an L domain when NC-p1-p6 was restored to its C terminus. Furthermore, when the NC domain was replaced by a leucine zipper, the p1-p6 region, but not p6 alone, conferred sensitivity to inhibition of the ESCRT pathway. In an authentic HIV-1 Gag context, the effect of an inhibitor of the ESCRT pathway on particle production could be alleviated by deleting a portion of the NC domain together with p1. Together, these results indicate that the ESCRT pathway dependence of HIV-1 budding is determined, at least in part, by the NC-p1 region of Gag.

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Efficient Particle Production by Minimal Gag Constructs Which Retain the Carboxy-Terminal Domain of Human Immunodeficiency Virus Type 1 Capsid-p2 and a Late Assembly Domain

Journal of Virology ◽

10.1128/jvi.74.12.5395-5402.2000 ◽

2000 ◽

Vol 74 (12) ◽

pp. 5395-5402 ◽

Cited By ~ 230

Author(s):

Molly A. Accola ◽

Bettina Strack ◽

Heinrich G. Göttlinger

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Leucine Zipper ◽

Particle Production ◽

Immunodeficiency Virus ◽

Carboxy Terminal ◽

Late Assembly Domain ◽

Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) Gag precursor Pr55 gag by itself is capable of assembling into retrovirus-like particles (VLP). In the present study, we attempted to identify the minimal Gag sequences required for the formation of VLP. Our results show that about 80% of Pr55 gag can be either deleted or replaced by heterologous sequences without significantly compromising VLP production. The smallest chimeric molecule still able to efficiently form VLP was only about 16 kDa. This minimal Gag construct contained the leucine zipper domain of the yeast transcription factor GCN4 to substitute for the assembly function of nucleocapsid (NC), followed by a P-P-P-P-Y motif to provide late budding (L) domain function, and retained only the myristylation signal and the C-terminal capsid-p2 domain of Pr55 gag . We also show that the L domain function of HIV-1 p6 gag is not dependent on the presence of an active viral protease and that the NC domain of Pr55 gag is dispensable for the incorporation of Vpr into VLP.

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Both Neutralization Resistance and High Infectivity Phenotypes Are Caused by Mutations of Interacting Residues in the Human Immunodeficiency Virus Type 1 gp41 Leucine Zipper and the gp120 Receptor- and Coreceptor-Binding Domains

Journal of Virology ◽

10.1128/jvi.73.7.5707-5713.1999 ◽

1999 ◽

Vol 73 (7) ◽

pp. 5707-5713 ◽

Cited By ~ 29

Author(s):

Eun Ju Park ◽

Gerald V. Quinnan

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Leucine Zipper ◽

Vaccine Development ◽

Viral Envelope ◽

C Terminus ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT Neutralization resistance of human immunodeficiency virus type 1 (HIV-1) is a major impediment to vaccine development. We have found that residues of HIV-1 MN strain in the C terminus of gp120 and the leucine zipper (LZ) region of gp41 viral envelope proteins interact cooperatively to determine neutralization resistance and modulate infectivity. Further, results demonstrate that this interaction, by which regions of gp120 are assembled onto the LZ, involves amino acid residues intimately related to those which participate in the binding of the envelope to its receptor and coreceptor. Variations in this critical assembly structure determine the concordant, interdependent evolution of increased infectivity efficiency and neutralization resistance phenotypes of the envelopes. The results elucidate important structure-function relationships among epitopes that are important targets of vaccine development.

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