Nef promotes evasion of human immunodeficiency virus type 1-infected cells from the CTLA-4-mediated inhibition of T-cell activation.
J Gen Virol
; 96(Pt 6): 1463-1477, 2015 Jun.
Article
em En
| MEDLINE
| ID: mdl-25626682
ABSTRACT
CTLA-4 is a negative regulator of T-cell receptor-mediated CD4(+) T-cell activation and function. Upregulation of CTLA-4 during human immunodeficiency virus type 1 (HIV-1) infection on activated T cells, particularly on HIV-specific CD4(+) T cells, correlates with immune dysfunction and disease progression. As HIV-1 infects and replicates in activated CD4(+) T cells, we investigated mechanisms by which HIV-1 modulates CTLA-4 expression to establish productive viral infection in these cells. Here, we demonstrate that HIV-1 infection in activated CD4(+) T cells was followed by Nef-mediated downregulation of CTLA-4. This was associated with a decreased T-cell activation threshold and significant resistance to CTLA-4 triggering. In line with these in vitro results, quantification of pro-viral HIV DNA from treatment-naive HIV-infected subjects demonstrated a preferential infection of memory CD4(+)CTLA-4(+) T cells, thus identifying CTLA-4 as a biomarker for HIV-infected cells in vivo. As transcriptionally active HIV-1 and Nef expression in vivo were previously shown to take place mainly in the CD3(+)CD4(-)CD8(-) [double-negative (DN)] cells, we further quantified HIV DNA in the CTLA-4(+) and CTLA-4(-) subpopulations of these cells. Our results showed that DN T cells lacking CTLA-4 expression were enriched in HIV DNA compared with DN CTLA-4(+) cells. Together, these results suggested that HIV-1 preferential infection of CD4(+)CTLA-4(+) T cells in vivo was followed by Nef-mediated concomitant downregulation of both CD4 and CTLA-4 upon transition to productive infection. This also highlights the propensity of HIV-1 to evade restriction of the key negative immune regulator CTLA-4 on cell activation and viral replication, and therefore contributes to the overall HIV-1 pathogenesis.
Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Linfócitos T Citotóxicos
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Linfócitos T CD4-Positivos
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HIV-1
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Produtos do Gene nef do Vírus da Imunodeficiência Humana
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Interações Hospedeiro-Patógeno
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Evasão da Resposta Imune
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Antígeno CTLA-4
Limite:
Adult
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Female
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Humans
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Male
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article