scholarly journals The Tat protein of human immunodeficiency virus type 1, a growth factor for AIDS Kaposi sarcoma and cytokine-activated vascular cells, induces adhesion of the same cell types by using integrin receptors recognizing the RGD amino acid sequence.

1993 ◽  
Vol 90 (17) ◽  
pp. 7941-7945 ◽  
Author(s):  
G. Barillari ◽  
R. Gendelman ◽  
R. C. Gallo ◽  
B. Ensoli
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Growth Factor ◽  
Amino Acid Sequence ◽  
Kaposi Sarcoma ◽  
Cell Types ◽  
Tat Protein ◽  
Integrin Receptors ◽  
Immunodeficiency Virus

scholarly journals A Naturally Occurring Substitution in Human Immunodeficiency Virus Tat Increases Expression of the Viral Genome

2003 ◽  
Vol 77 (15) ◽  
pp. 8602-8606 ◽  
Author(s):  
Syed M. Reza ◽  
Lin-Ming Shen ◽  
Rupa Mukhopadhyay ◽  
Mihaela Rosetti ◽  
Tsafi Pe'ery ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Elongation Factor ◽  
Deleterious Mutations ◽  
Tat Protein ◽  
Virulent Strains ◽  
Etiologic Agents ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT A natural amino acid substitution in the human immunodeficiency virus type 1 (HIV-1) transcriptional activator Tat increases its activity and compensates for deleterious mutations elsewhere in the Tat protein. Substitution of asparagine for threonine 23 increases Tat transactivation of the HIV-1 promoter and the binding of Tat to the cellular kinase positive transcription elongation factor b (P-TEFb). Of nine other position 23 mutations tested, only the serine substitution retained wild-type activity. Correspondingly, asparagine is the most frequent amino acid at this position in HIV-1 isolates, followed by threonine and serine. Asparagine is prevalent in Tat proteins of viruses in clades A, C, and D, which are major etiologic agents of AIDS. We suggest that selection for asparagine in position 23 confers an advantage to the virus, since it can compensate for deleterious mutations in Tat. It may also support the replication of otherwise less fit drug-resistant viruses and permit the emergence of virulent strains.

scholarly journals Frequent Detection of Escape from Cytotoxic T-Lymphocyte Recognition in Perinatal Human Immunodeficiency Virus (HIV) Type 1 Transmission: the Ariel Project for the Prevention of Transmission of HIV from Mother to Infant

1999 ◽  
Vol 73 (5) ◽  
pp. 3975-3985 ◽  
Author(s):  
Cara C. Wilson ◽  
R. Clark Brown ◽  
Bette T. Korber ◽  
Barbara M. Wilkes ◽  
Debbie J. Ruhl ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Sequence Variation ◽  
Amino Acid Sequence Variation ◽  
Immunodeficiency Virus ◽  
Immunologic Factors ◽  
Hiv Type 1 ◽  
Hiv 1

ABSTRACT Host immunologic factors, including human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes (CTL), are thought to contribute to the control of HIV type 1 (HIV-1) replication and thus delay disease progression in infected individuals. Host immunologic factors are also likely to influence perinatal transmission of HIV-1 from infected mother to infant. In this study, the potential role of CTL in modulating HIV-1 transmission from mother to infant was examined in 11 HIV-1-infected mothers, 3 of whom transmitted virus to their offspring. Frequencies of HIV-1-specific human leukocyte antigen class I-restricted CTL responses and viral epitope amino acid sequence variation were determined in the mothers and their infected infants. Maternal HIV-1-specific CTL clones were derived from each of the HIV-1-infected pregnant women. Amino acid substitutions within the targeted CTL epitopes were more frequently identified in transmitting mothers than in nontransmitting mothers, and immune escape from CTL recognition was detected in all three transmitting mothers but in only one of eight nontransmitting mothers. The majority of viral sequences obtained from the HIV-1-infected infant blood samples were susceptible to maternal CTL. These findings demonstrate that epitope amino acid sequence variation and escape from CTL recognition occur more frequently in mothers that transmit HIV-1 to their infants than in those who do not. However, the transmitted virus can be a CTL susceptible form, suggesting inadequate in vivo immune control.

scholarly journals Role of the Specific Amino Acid Sequence of the Membrane-Spanning Domain of Human Immunodeficiency Virus Type 1 in Membrane Fusion

2005 ◽  
Vol 79 (8) ◽  
pp. 4720-4729 ◽  
Author(s):  
Kosuke Miyauchi ◽  
Jun Komano ◽  
Yoshiyuki Yokomaku ◽  
Wataru Sugiura ◽  
Naoki Yamamoto ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Membrane Fusion ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Specific Amino Acid ◽  
Immunodeficiency Virus ◽  
Membrane Spanning

ABSTRACT Fusion between cell and virus membranes mediated by gp41 initiates the life cycle of human immunodeficiency virus type 1. In contrast to the many studies that have elucidated the structure-function relationship of the ectodomain, the study of the membrane-spanning domain (MSD) has been rather limited. In particular, the role that the MSD's specific amino acid sequences may have in membrane fusion as well as other gp41 functions is not well understood. The MSD of gp41 contains well-conserved glycine residues that form the GXXXG motif (G, glycine; X, other amino acid residues), a motif often found at the helix-helix interface of membrane spanning α-helices. Here we examined the role that the specific amino acid sequence of the gp41 MSD has in gp41 function, particularly in membrane fusion, by making two types of MSD mutants: (i) glycine substitution mutants in which glycine residues of the MSD were mutated to alanine or leucine residues, and (ii) replacement mutants in which the entire MSD was replaced with one derived from glycophorin A or from vesicular stomatitis virus G. The substitution of glycines did not affect gp41 function. MSD-replacement mutants, however, showed severely impaired fusion activity. The assay using the Env expression vector revealed defects in membrane fusion after CD4 binding steps in the MSD-replacement mutants. In addition, the change in Env processing was noted for MSD-replacement mutants. These results suggest that the MSD of gp41 has a relatively wide but not unlimited tolerance for mutations and plays a critical role in membrane fusion as well as in other steps of Env biogenesis.

Activation of transcription factor NF-kappaB by the Tat protein of human immunodeficiency virus type 1.

1996 ◽  
Vol 70 (7) ◽  
pp. 4427-4437 ◽  
Author(s):  
F Demarchi ◽  
F d'Adda di Fagagna ◽  
A Falaschi ◽  
M Giacca
Keyword(s):  
Human Immunodeficiency Virus ◽  
Transcription Factor ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Tat Protein ◽  
Activation Of Transcription ◽  
Immunodeficiency Virus ◽  
Nf Kappab

scholarly journals Human Immunodeficiency Virus Type 1 Replication in the Absence of Integrase-Mediated DNA Recombination: Definition of Permissive and Nonpermissive T-Cell Lines

2001 ◽  
Vol 75 (17) ◽  
pp. 7944-7955 ◽  
Author(s):  
Noriko Nakajima ◽  
Richard Lu ◽  
Alan Engelman
Keyword(s):  
Human Immunodeficiency Virus ◽  
Cell Lines ◽  
Dna Recombination ◽  
Cell Types ◽  
Class Ii ◽  
Class I ◽  
Immunodeficiency Virus ◽  
T Cell Lines ◽  
Hiv 1

ABSTRACT Functional retroviral integrase protein is thought to be essential for productive viral replication. Yet, previous studies differed on the extent to which integrase mutant viruses expressed human immunodeficiency virus type 1 (HIV-1) genes from unintegrated DNA. Although one reason for this difference was that class II integrase mutations pleiotropically affected the viral life cycle, another reason apparently depended on the identity of the infected cell. Here, we analyzed integrase mutant viral infectivities in a variety of cell types. Single-round infectivity of class I integration-specific mutant HIV-1 ranged from <0.03 to 0.3% of that of the wild type (WT) across four different T-cell lines. Based on this approximately 10-fold influence of cell type on mutant gene expression, we examined class I and class II mutant replication kinetics in seven different cell lines and two primary cell types. Unexpectedly, some cell lines supported productive class I mutant viral replication under conditions that restricted class II mutant growth. Cells were defined as permissive, semipermissive, or nonpermissive based on their ability to support the continual passage of class I integration-defective HIV-1. Mutant infectivity in semipermissive and permissive cells as quantified by 50% tissue culture infectious doses, however, was only 0.0006 to 0.005% of that of WT. Since the frequencies of mutant DNA recombination in these lines ranged from 0.023 to <0.093% of the WT, we conclude that productive replication in the absence of integrase function most likely required the illegitimate integration of HIV-1 into host chromosomes by cellular DNA recombination enzymes.

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