Nef Is Required for Efficient HIV-1 Replication in Cocultures of Dendritic Cells and Lymphocytes

Petit, Caroline; Buseyne, Florence; Boccaccio, Claire; Abastado, Jean-Pierre; Heard, Jean‐Michel; Schwartz, Olivier

doi:10.1006/viro.2001.0984

Cited by 66 publications

(61 citation statements)

References 72 publications

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“…The production and use of WT and mutant HIV (from NL4.3 or NLAD8 strains) have been described (77,78). For HIV replication experiments, freshly prepared PBMCs were exposed to the indicated virus stocks (viral input ranging from 20 to 0.02 ng of p24/10 6 cells) for 2 h 30 min, washed twice with phosphate-buffered saline, and cultured in 96-well plates (2 ϫ 10 5 cells/well, in triplicates).…”

Section: Methodsmentioning

confidence: 99%

The Effects of HIV-1 Nef on CD4 Surface Expression and Viral Infectivity in Lymphoid Cells Are Independent of Rafts

Sol‐Foulon¹,

Esnault²,

Percherancier

et al. 2004

Journal of Biological Chemistry

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The HIV-1 Nef protein is a critical virulence factor that exerts multiple effects during viral replication. Nef modulates surface expression of various cellular proteins including CD4 and MHC-I, enhances viral infectivity, and affects signal transduction pathways. Nef has been shown to partially associate with rafts, where it can prime T cells for activation. The contribution of rafts during Nef-induced CD4 down-regulation and enhancement of viral replication remains poorly understood. We show here that Nef does not modify the palmitoylation state of CD4 or its partition within rafts. Moreover, CD4 mutants lacking palmitoylation or unable to associate with rafts are efficiently down-regulated by Nef. In HIV-infected cells, viral assembly and budding occurs from rafts, and Nef has been suggested to increase this process. However, using T cells acutely infected with wild-type or nef-deleted HIV, we did not observe any impact of Nef on raft segregation of viral structural proteins. We have also designed a palmitoylated mutant of Nef (NefG3C), which significantly accumulates in rafts. Interestingly, the efficiency of NefG3C to down-regulate CD4 and MHC-I, and to promote viral replication was not increased when compared with the wild-type protein. Altogether, these results strongly suggest that rafts are not a key element involved in the effects of Nef on trafficking of cellular proteins and on viral replication.

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Section: Methodsmentioning

confidence: 99%

The Effects of HIV-1 Nef on CD4 Surface Expression and Viral Infectivity in Lymphoid Cells Are Independent of Rafts

Sol‐Foulon¹,

Esnault²,

Percherancier

et al. 2004

Journal of Biological Chemistry

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“…Incoming virions are rapidly degraded in DCs and in DC-SIGN ϩ cells (43,57). There is thus an apparent discrepancy between the short halflife of incoming virions (Ͻ3 h) and the ability of DCs and DC-SIGN ϩ cell lines to retain and transmit the infection to T cells, which has been observed up to 6 days after viral exposure (19,45,54).…”

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confidence: 99%

“…DCs express low levels of CD4 and coreceptors CCR5 or CXCR4. It has been reported that R5, but not X4, HIV-1 strains replicate in immature monocyte-derived DCs (21,45,47). However, both R5 and X4 viruses readily enter DCs and are able to perform reverse transcription (RT) in these cells (3,9,14,(22)(23)(24).…”

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confidence: 99%

“…However, both R5 and X4 viruses readily enter DCs and are able to perform reverse transcription (RT) in these cells (3,9,14,(22)(23)(24). Of note, both X4 and R5 strains are efficiently transmitted, even a few days after viral exposure, from DCs to lymphocytes (19,45). However, with R5 strains, which replicate in DCs, viral progeny (but not incoming virions) are transmitted after a few hours (57).…”

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confidence: 99%

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Covert Human Immunodeficiency Virus Replication in Dendritic Cells and in DC-SIGN-Expressing Cells Promotes Long-Term Transmission to Lymphocytes

Nobile

Petit

Moris

et al. 2005

J Virol

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129

139

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HIV-1 virions are efficiently captured by monocyte-derived immature dendritic cells (iDCs), as well as by cell lines expressing the lectin DC-SIGN. Viral infectivity can be retained for several days, and even enhanced, before transmission to CD4 ؉ lymphocytes. The role of DC-SIGN in viral retention and enhancement of infection is not fully understood and varies according to the cell line expressing the lectin. We studied here the mechanisms underlying this process. We focused our study on X4-tropic human immunodeficiency virus (HIV) strains, since they were widely believed not to replicate in iDCs. However, we first show that X4 HIV replicates covertly and slowly in iDCs. This is also the case in Raji-DC-SIGN cells, which are classically used to study HIV transmission. We used either single-cycle or replicative HIV and measured viral RT and replication to further demonstrate that transfer of incoming virions from iDCs or DC-SIGN ؉ cells occurs only on the short-term (i.e., a few hours after viral exposure). There is no long-term storage of original HIV particles in these cells. A few days after viral exposure, replicative viruses, and not single-cycle virions, are transmitted to CD4؉ cells. The cell-type-dependent activity of DC-SIGN reflects the ability of HIV to replicate covertly in some cells, and not in others.

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“…SIV (27) and HIV (28) replication in immature DC-T cell cocultures is dependent on the presence of nef. Yet mature DCs readily promote SIV delta nef (delta nef) growth (27), suggesting that when a mature DC encounters the virus it somehow overrides the need for nef.…”

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confidence: 99%

Endogenously Expressed nef Uncouples Cytokine and Chemokine Production from Membrane Phenotypic Maturation in Dendritic Cells

Messmer

Jacqué

Santisteban

et al. 2002

The Journal of Immunology

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Immature dendritic cells (DCs), unlike mature DCs, require the viral determinant nef to drive immunodeficiency virus (SIV and HIV) replication in coculture with CD4+ T cells. Since immature DCs may capture and get infected by virus during mucosal transmission, we hypothesized that Nef associated with the virus or produced during early replication might modulate DCs to augment virus dissemination. Adenovirus vectors expressing nef were used to introduce nef into DCs in the absence of other immunodeficiency virus determinants to examine Nef-induced changes that might activate immature DCs to acquire properties of mature DCs and drive virus replication. Nef expression by immature human and macaque DCs triggered IL-6, IL-12, TNF-α, CXCL8, CCL3, and CCL4 release, but without up-regulating costimulatory and other molecules characteristic of mature DCs. Coincident with this, nef-expressing immature DCs stimulated stronger autologous CD4+ T cell responses. Both SIV and HIV nef-expressing DCs complemented defective SIVmac239 delta nef, driving replication in autologous immature DC-T cell cultures. In contrast, if DCs were activated after capturing delta nef, virus growth was not exacerbated. This highlights one way in which nef-defective virus-bearing immature DCs that mature while migrating to draining lymph nodes could induce stronger immune responses in the absence of overwhelming productive infection (unlike nef-containing wild-type virus). Therefore, Nef expressed in immature DCs signals a distinct activation program that promotes virus replication and T cell recruitment but without complete DC maturation, thereby lessening the likelihood that wild-type virus-infected immature DCs would activate virus-specific immunity, but facilitating virus dissemination.

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Nef Is Required for Efficient HIV-1 Replication in Cocultures of Dendritic Cells and Lymphocytes

Cited by 66 publications

References 72 publications

The Effects of HIV-1 Nef on CD4 Surface Expression and Viral Infectivity in Lymphoid Cells Are Independent of Rafts

The Effects of HIV-1 Nef on CD4 Surface Expression and Viral Infectivity in Lymphoid Cells Are Independent of Rafts

Covert Human Immunodeficiency Virus Replication in Dendritic Cells and in DC-SIGN-Expressing Cells Promotes Long-Term Transmission to Lymphocytes

Endogenously Expressed nef Uncouples Cytokine and Chemokine Production from Membrane Phenotypic Maturation in Dendritic Cells

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