scholarly journals Genetic and Functional Diversity of Human Immunodeficiency Virus Type 1 Subtype B Nef Primary Isolates

2001 ◽  
Vol 75 (4) ◽  
pp. 1672-1680 ◽  
Author(s):  
John L. Foster ◽  
Rene P. Molina ◽  
Tianci Luo ◽  
Vivek K. Arora ◽  
Yaoxing Huang ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mhc Class I ◽  
Mutational Analysis ◽  
Infected Individual ◽  
Class I ◽  
Structural Basis ◽  
Amino Acid Residues ◽  
Subtype B ◽  
Immunodeficiency Virus ◽  
Hiv Subtypes

ABSTRACT We have characterized the functional integrity of seven primary Nef isolates: five from a long-term nonprogressing human immunodeficiency virus (HIV)-infected individual and one each from two patients with AIDS. One of the seven Nefs was defective for CD4 downregulation, two others were defective for PAK-2 activation, and one Nef was defective for PAK-2 activation and major histocompatibility complex (MHC) class I downregulation. Five of the Nefs were tested and found to be functional for the enhancement of virus particle infectivity. The structural basis for each of the functional defects has been analyzed by constructing a consensus nef, followed by mutational analysis of the variant amino acid residues. Mutations A29V and F193I were deleterious to CD4 downregulation and PAK-2 activation, respectively, while S189R rendered Nef defective for both MHC class I downregulation and PAK-2 activation. A search of the literature identified HIVs from five patients with Nefs predominantly mutated at F193 and from one patient with Nefs predominantly mutated at A29. A29 is highly conserved in all HIV subtypes except for subtype E. F193 is conserved in subtype B (and possibly in the closely related subtype D), but none of the other HIV group M subtypes. Our results suggest that functional distinctions may exist between HIV subtypes.

scholarly journals Dynamic Evolution of the Human Immunodeficiency Virus Type 1 Pathogenic Factor, Nef

2006 ◽  
Vol 80 (3) ◽  
pp. 1311-1320 ◽  
Author(s):  
Eduardo O'Neill ◽  
Lillian S. Kuo ◽  
John F. Krisko ◽  
Diana R. Tomchick ◽  
J. Victor Garcia ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mhc Class I ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Early Gene ◽  
Class I ◽  
Subtype B ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The human immunodeficiency virus type 1 (HIV-1) early gene product Nef is a multifunctional protein that alters numerous pathways of T-cell function, including endocytosis, signal transduction, vesicular trafficking, and immune modulation, and is a major determinant of pathogenesis. Individual Nef functions include PAK-2 activation, CD4 downregulation, major histocompatibility complex (MHC) class I downregulation, and enhancement of viral particle infectivity. How Nef accomplishes its multiple tasks presents a difficult problem of mechanistic analysis because of the complications associated with multiple, overlapping functional domains in the context of significant sequence variability. To address these issues we determined the conservation of each Nef residue based on 1,643 subtype B Nef sequences. Mutational analysis based on conservative substitutions and Nef sequence data allowed us to search for amino acids on the surface of Nef that are specifically required for PAK-2 activation. We found residues 85, 89, and 191 to be highly significant determinants for Nef's PAK-2 activation function but functionally unlinked to CD4 and MHC class I downregulation or enhancement of infectivity. These residues are not conserved across HIV-1 subtypes but are confined to separate sets of surface elements within a subtype. Thus, L85/H89/F191 and F85/F89/R191 are dominant in subtype B and subtype E or C, respectively. Our results provide support for developing subtype-specific interventions in HIV-1 disease.

scholarly journals Nef from a primary isolate of human immunodeficiency virus type 1 lacking the EE155 region shows decreased ability to down-regulate CD4

2004 ◽  
Vol 85 (6) ◽  
pp. 1451-1461 ◽  
Author(s):  
Young-Soon Na ◽  
Keejung Yoon ◽  
Jeong-Gu Nam ◽  
Byeongsun Choi ◽  
Joo-Shil Lee ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mhc Class I ◽  
Infected Individual ◽  
Laboratory Strain ◽  
Class I ◽  
Target Cells ◽  
Down Regulation ◽  
Immunodeficiency Virus ◽  
Infected Cells

The human immunodeficiency virus (HIV) nef gene encodes a 27 kDa myristoylated cytosolic protein that has an important role in the pathogenesis of AIDS. One function of Nef is the down-regulation of CD4 and MHC class I surface molecules in HIV-infected cells. Nef directly isolated from an infected individual (KS2), who could be defined as a long-term non-progressor, was compared with Nef from a standard laboratory strain, HIV-1 NL4-3. KS2 Nef protein was characterized by its lowered ability to down-regulate CD4, while still maintaining the ability to down-regulate MHC class I. The ability of KS2 Nef to down-regulate CD4 was more prominent when CD4 was measured 2–3 days after transfer of the nef gene to the target cells, and also when the effect was measured in CD4+-enriched primary T cells. The amino acid sequence analysis indicated that the most notable feature of KS2 Nef was lack of the two glutamic acids: the EE155 region. When the EE155 region was added to KS2 Nef, the CD4 down-regulation ability was increased almost to the level of NL4-3 Nef. Conversely, when the EE155 region was deleted from NL4-3, its CD4 down-regulation ability was dramatically impaired. These data suggested that the EE155 region plays an important role(s) in the down-regulation of CD4 by Nef protein and also that primary nef sequences could be very useful in identifying the original biological functions of Nef in vivo.

scholarly journals Autoreactive cytotoxic T lymphocytes in human immunodeficiency virus type 1-infected subjects.

1996 ◽  
Vol 183 (6) ◽  
pp. 2509-2516 ◽  
Author(s):  
F di Marzo Veronese ◽  
D Arnott ◽  
V Barnaba ◽  
D J Loftus ◽  
K Sakaguchi ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Lymphocytes ◽  
Mhc Class I ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Class I ◽  
Immunodeficiency Virus ◽  
Hla A2.1 ◽  
Hiv 1

A subtractive analysis of peptides eluted from major histocompatibility complex (MHC) class I human histocompatibility leukocyte antigen (HLA)-A2.1 molecules purified from either human immunodeficiency virus type-1 (HIV-1)-infected or uninfected cells was performed using micro high-performance liquid chromatography and mass spectrometry. Three peptides unique to infected cells were identified and found to derive from a single protein, human vinculin, a structural protein not known to be involved in viral pathogenesis. Molecular and cytofluorometric analyses revealed vinculin mRNA and vinculin protein overexpression in B and T lymphocytes from HIV-1-infected individuals. Vinculin peptide-specific CTL activity was readily elicited from peripheral blood lymphocytes of the majority of HLA-A2.1+, HIV+ patients tested. Our observations suggest that atypical vinculin expression and MHC class I-mediated presentation of vinculin-derived peptides accompany HIV infection of lymphoid cells in vivo, with a resultant induction of antivinculin CTL in a significant portion of HIV+ (HLA-A2.1+) individuals.

scholarly journals Vaccine-Elicited Memory Cytotoxic T Lymphocytes Contribute to Mamu-A*01-Associated Control of Simian/Human Immunodeficiency Virus 89.6P Replication in Rhesus Monkeys

2005 ◽  
Vol 79 (8) ◽  
pp. 4580-4588 ◽  
Author(s):  
Michael S. Seaman ◽  
Sampa Santra ◽  
Michael H. Newberg ◽  
Valerie Philippon ◽  
Kelledy Manson ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mhc Class I ◽  
T Lymphocyte ◽  
Rhesus Monkeys ◽  
Cytotoxic T Lymphocyte ◽  
Class I ◽  
Immunodeficiency Virus ◽  
Memory Cytotoxic T Lymphocytes ◽  
The Impact ◽  
Ctl Responses

ABSTRACT The expression of particular major histocompatibility complex (MHC) class I alleles can influence the rate of disease progression following lentiviral infections. This effect is a presumed consequence of potent cytotoxic T-lymphocyte (CTL) responses that are restricted by these MHC class I molecules. The present studies have examined the impact of the MHC class I allele Mamu-A*01 on simian/human immunodeficiency virus 89.6P (SHIV-89.6P) infection in unvaccinated and vaccinated rhesus monkeys by exploring the contribution of dominant-epitope specific CTL in this setting. Expression of Mamu-A*01 in immunologically naive monkeys was not associated with improved control of viral replication, CD4+ T-lymphocyte loss, or survival. In contrast, Mamu-A*01 + monkeys that had received heterologous prime/boost immunizations prior to challenge maintained higher CD4+ T-lymphocyte levels and better control of SHIV-89.6P replication than Mamu-A*01 − monkeys. This protection was associated with the evolution of high-frequency anamnestic CTL responses specific for a dominant Mamu-A*01-restricted Gag epitope following infection. These data indicate that specific MHC class I alleles can confer protection in the setting of a pathogenic SHIV infection by their ability to elicit memory CTL following vaccination.

scholarly journals Mutation of a Conserved Residue (D123) Required for Oligomerization of Human Immunodeficiency Virus Type 1 Nef Protein Abolishes Interaction with Human Thioesterase and Results in Impairment of Nef Biological Functions

2000 ◽  
Vol 74 (11) ◽  
pp. 5310-5319 ◽  
Author(s):  
Lang Xia Liu ◽  
Nikolaus Heveker ◽  
Oliver T. Fackler ◽  
Stefan Arold ◽  
Sylvie Le Gall ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mhc Class I ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
T Cell Activation ◽  
Class I ◽  
Viral Infectivity ◽  
Immunodeficiency Virus ◽  
Conserved Residue

ABSTRACT Nef is a myristoylated protein of 27 to 35 kDa that is conserved in primate lentiviruses. In vivo, Nef is required for high viral load and full pathological effects. In vitro, Nef has at least four activities: induction of CD4 and major histocompatibility complex (MHC) class I downregulation, enhancement of viral infectivity, and alteration of T-cell activation pathways. We previously reported that the Nef protein from human immunodeficiency virus type 1 interacts with a novel human thioesterase (hTE). In the present study, by mutational analysis, we identified a region of the Nef core, extending from the residues D108 to W124, that is involved both in Nef-hTE interaction and in Nef-induced CD4 downregulation. This region of Nef is located on the oligomer interface and is in close proximity to the putative CD4 binding site. One of the mutants carrying a mutation in this region, targeted to the conserved residue D123, was also found to be defective in two other functions of Nef, MHC class I downmodulation and enhancement of viral infectivity. Furthermore, mutation of this residue affected the ability of Nef to form dimers, suggesting that the oligomerization of Nef may be critical for its multiple functions.

scholarly journals Mamu-A*01 Allele-Mediated Attenuation of Disease Progression in Simian-Human Immunodeficiency Virus Infection

2002 ◽  
Vol 76 (24) ◽  
pp. 12845-12854 ◽  
Author(s):  
Zhi-Qiang Zhang ◽  
Tong-Ming Fu ◽  
Danilo R. Casimiro ◽  
Mary-Ellen Davies ◽  
Xiaoping Liang ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Virus Infection ◽  
Disease Progression ◽  
Mhc Class I ◽  
Cytotoxic T Lymphocyte ◽  
Class I ◽  
Aids Vaccine ◽  
Immunodeficiency Virus ◽  
Shiv Infection

ABSTRACT Expression of several major histocompatibility complex (MHC) class I alleles is associated with a protective effect against disease progression in both human immunodeficiency virus type 1 and simian immunodeficiency virus infection. To understand the mechanism underlying this effect, we investigated the expression of the MHC class I allele Mamu-A*01 in simian-human immunodeficiency virus (SHIV) infection, one of the major models for evaluation of AIDS vaccine candidates. We found that disease progression was significantly delayed in Mamu-A∗01-positive rhesus monkeys infected with the highly pathogenic SHIV 89.6P. The delay corresponded not only to a noted Mamu-A∗01-restricted dominant cytotoxic T-lymphocyte (CTL) response but also to a lower viral load in lymph nodes (LN) and, importantly, to minimal destruction of LN structure during early infection. In contrast, Mamu-A∗01-negative monkeys exhibited massive destruction of LN structure with accompanying rapid disease progression. These data indicate that MHC class I allele-restricted CTL responses may play an important role in preservation of lymphoid tissue structure, thereby resulting in attenuation of disease progression in immunodeficiency virus infection.

scholarly journals Human Immunodeficiency Virus Type 1 Nef-Mediated Downregulation of CD4 Correlates with Nef Enhancement of Viral Pathogenesis

2003 ◽  
Vol 77 (3) ◽  
pp. 2124-2133 ◽  
Author(s):  
Cheryl A. Stoddart ◽  
Romas Geleziunas ◽  
Sharon Ferrell ◽  
Valerie Linquist-Stepps ◽  
Mary E. Moreno ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Mhc Class I ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Class I ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The nef gene products encoded by human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus type 1 (SIV-1) increase viral loads in infected hosts and accelerate clinical progression to AIDS. Nef exhibits a spectrum of biological activities, including the ability to downregulate surface expression of CD4 and major histocompatibility complex (MHC) class I antigens, to alter the state of T-cell activation, and to enhance the infectivity of viral particles. To determine which of these in vitro functions most closely correlates with the pathogenic effects of Nef in vivo, we constructed recombinant HIV-1 NL4-3 viruses carrying mutations within the nef gene that selectively impair these functions. These mutant viruses were evaluated for pathogenic potential in severe combined immunodeficiency (SCID) mice implanted with human fetal thymus and liver (SCID-hu Thy/Liv mice), in which virus-mediated depletion of thymocytes is known to be Nef dependent. Disruption of the polyproline type II helix (Pxx)4 within Nef (required for binding of Hck and p21-activated kinase-like kinases, downregulation of MHC class I, and enhancement of HIV-1 infectivity in vitro but dispensable for CD4 downregulation) did not impair thymocyte depletion in virus-infected Thy/Liv human thymus implants. Conversely, three separate point mutations in Nef that compromised its ability to downregulate CD4 attenuated thymocyte depletion while not diminishing viral replication. These findings indicate that the functional ability of Nef to downregulate CD4 and not MHC class I downregulation, Hck or PAK binding, or (Pxx)4-associated enhancement of infectivity most closely correlates with Nef-mediated enhancement of HIV-1 pathogenicity in vivo. Nef-mediated CD4 downregulation merits consideration as a new target for the development of small-molecule inhibitors.

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