Identification of Nef-HIV-1 domains involved in p22-phox interaction and superoxide production / Identificación del dominio de Nef-VIH-1 involucrado en la interacción con p22-phox y producción de superoxido

Nef -HIV-1 has been shown to be involved in NADPH complex interaction and superoxide production. The aim of this work was to study the domains involved in the interaction between Nef and p22-phox. Two approaches were used: 1) in silico modelling, to determine the potential binding motifs and design Nef truncated forms and 2) functional assays. The results showed that GFPVT 68-72, FPDW 121-124 and REVLE 179-183 on Nef are critical for p22-phox (RPQIG 142-146 and PGGP 181-184) docking. However, only the region containing FPDW 121-124 on Nef is able to induce superoxide production. Understanding the molecular mechanisms involved in generating oxidative stress during HIV infection, is critical for therapeutic intervention, in order to minimize viral replication and dissemination.

Se ha evidenciado que Nef-VIH-1 está involucrado en la interacción con el complejo NADPH y la producción de superóxido. El objetivo de este trabajo fue identificar los dominios implicados en la interacción entre Nef y p22-phox. Se utilizaron dos estrategias: 1) análisis in silico para determinar los posibles motivos de unión y el diseño Nef formas truncadas y 2) ensayos funcionales. Los resultados mostraron que GFPVT 68-72, FPDW 121 a 124 y 179 a 183 REVLE de Nef son críticos para su unión con p22-phox (RPQIG 142-146 y 181-184 PGGP). Sin embargo, sólo la región que contiene FPDW 121-124 en Nef, es capaz de inducir la producción de superóxido. La comprensión de los mecanismos moleculares implicados en la generación de estrés oxidativo durante la infección por VIH, es crítico para la intervención terapéutica, con el fin de minimizar la replicación y la propagación viral.

Analysis of genetic diversity of HIV-1 nef genes from a patient with AIDS dementia complex / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To study the genetic diversity of HIV-1 nef genes from a patient with AIDS dementia complex(ADC) , so as to research the amino acid variability and the pathogenesis of ADC.</p><p><b>METHODS</b>The nef gene was amplified with PCR from genomic DNA which was extracted from spleen and different brain tissues(basal ganglia, frontal gray matter, meninges, temporal lobe)of a patient who died of ADC. PCR products were cloned into the pMD19-T vector, after transformation and selection by ampicillin and blue/white spotting. Five of positive clones were sequenced and confirmed with BLAST. HIV-1 nef sequences were processed with BioEdit and MEGA4 to do Neighbor-Joining tree, p-Distances, and values of ds/dn.</p><p><b>RESULTS</b>The samples were all identified as HIV-1 B and genetic variation exists in HIV-1 nef gene isolated from different tissues compared with HXB2. In addition,part of the changes were different between periphery and brain.</p><p><b>CONCLUSION</b>Variations exist in the HIV-1 nef gene extracted from the ADC patient and the variations from peripheral and central nerve tissues were different,these variations may change the function of Nef,and it needs more research.</p>

Association between Nef-specific CD8 T-cell responses and disease progression in HIV-1 subtype B infection / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The correlation between HIV-1 Nef-specific CD8 T-cell responses and markers of HIV-1 disease progression still remains unclear. This study analysed and compared the role of HIV-1 Nef-specific CD8 T-cell responses in patients with different disease status.</p><p><b>METHODS</b>Two groups of patients with HIV-1 subtype B infection were selected according to CD4 count and clinical manifestations: long-term nonprogressors (LTNPs, n = 20) and advanced progressors (APs, CD4 count < 500 cells/microl, n = 34). Nef-specific CD8 T-cell responses were studied by interferon-gamma ELISpot assay against 3 pools of HIV-Nef peptides.</p><p><b>RESULTS</b>Nef-specific CD8 T-cell responses did not correlate with viral load or CD4 count in all patients and no significant differences were found in the magnitude of Nef-specific CD8 T-cell responses between groups LTNPs and APs (670 SFC/10(6) peripheral blood mononuclear cells vs 1107 SFC/10(6) peripheral blood mononuclear cells, P = 0.255). Further comparisons showed that there were also no significant correlations observed in group LTNPs, but Nef-specific CD8 T cells correlated negatively with viral load (r = -0.397, P = 0.020) and positively with CD4 count (r = 0.364, P = 0.034) in group APs.</p><p><b>CONCLUSION</b>These data suggest that different correlation patterns between Nef-specific CD8 T-cell responses and disease progression exist in LTNPs and APs. Although a negative association was observed with concurrent plasma HIV RNA in APs, Nef-specific CD8 T-cell responses might fail to play a protective role in different stages of HIV-1 infection.</p>

Biology of the HIV Nef protein.

The accessory Nef protein is expressed by all primate lentiviruses--HIV-1,HIV-2 and simian immune deficiency virus (SIV). Its expression in the early stages of the viral life cycle ensures two basic attributes of HIV infection. These are T-cell activation and the establishment of a persistent state of infection. Nef has a positive effect on viral infection and replication by promoting the survival of infected cells. Its role in HIV persistence is based largely on the ability of Nef to downmodulate the surface levels of important molecules at the immune synapse. These include major histocompatibility complex-I (MHC I) and (MHC II) present on antigen-presenting cells (APCs) and target cells, and CD4 and CD28 present on helper T cells. In this review we present these biological properties of Nef from a mechanistic point of view, and relate them to the structural attributes and interactions of the Nef protein. A brief outline of the limited studies on Nef from Indian subtype C HIV-1 isolates is also presented.

HIV-1 Nef control of cell signalling molecules: multiple strategies to promote virus replication.

HIV-1 has at its disposal numerous proteins encoded by its genome which provide the required arsenal to establish and maintain infection in its host for a considerable number of years. One of the most important and enigmatic of these proteins is Nef. The Nef protein of HIV-1 plays a fundamental role in the virus life cycle. This small protein of approximately 27 kDa is required for maximal virus replication and disease progression. The mechanisms by which it is able to act as a positive factor during virus replication is an area of intense research and although some controversy surrounds Nef much has been gauged as to how it functions. Its ability to modulate the expression of key cellular receptors important for cell activation and control signal transduction elements and events by interacting with numerous cellular kinases and signalling molecules, including members of the Src family kinases, leading to an effect on host cell function is likely to explain at least in part its role during infection and represents a finely tuned mechanism where this protein assists HIV-1 to control its host.