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Tetherin does not significantly restrict dendritic cell-mediated HIV-1 transmission and its expression is upregulated by newly synthesized HIV-1 Nef.

Coleman CM, Spearman P, Wu L - Retrovirology (2011)

Bottom Line: High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs.Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.

ABSTRACT

Background: Dendritic cells (DCs) are among the first cells to encounter HIV-1 and play important roles in viral transmission and pathogenesis. Immature DCs allow productive HIV-1 replication and long-term viral dissemination. The pro-inflammatory factor lipopolysaccharide (LPS) induces DC maturation and enhances the efficiency of DC-mediated HIV-1 transmission. Type I interferon (IFN) partially inhibits HIV-1 replication and cell-cell transmission in CD4+ T cells and macrophages. Tetherin is a type I IFN-inducible restriction factor that blocks HIV-1 release and modulates CD4+ T cell-mediated cell-to-cell transmission of HIV-1. However, the role of type I IFN and tetherin in HIV-1 infection of DCs and DC-mediated viral transmission remains unknown.

Results: We demonstrated that IFN-alpha (IFNα)-induced mature DCs restricted HIV-1 replication and trans-infection of CD4+ T cells. Tetherin expression in monocyte-derived immature DCs was undetectable or very low. High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs. Knockdown of induced tetherin in LPS- or IFNα-matured DCs modestly enhanced HIV-1 transmission to CD4+ T cells, but had no significant effect on wild-type HIV-1 replication in mature DCs. Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.

Conclusions: The restriction of HIV-1 replication and transmission in IFNα-induced mature DCs indicates a potent anti-HIV-1 response; however, high levels of tetherin induced in mature DCs cannot significantly restrict wild-type HIV-1 release and DC-mediated HIV-1 transmission. Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

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HIV-1 replication in iDCs upregulates tetherin independently of Vpu. (A) Supernatants from DCs infected with WT HIV-1 NL(AD8) or NL(AD8)ΔVpu were assessed for p24 concentration to quantify HIV-1 release. Cell lysates from iDC (B), mDC-LPS (C), and mDC-IFNα (D) infected with HIV-1 or mock infected were detected by immunoblotting for the expression of HIV-1 Gag (p55 and p24), tetherin, and GAPDH at 2 h, 3, 5 and 7 days post-infection (dpi). M, mock infection; W, WT NL(AD8); Δ, NL(AD8)ΔVpu. (E) Flow cytometry analyses of cell surface tetherin expression in iDCs infected with WT NL(AD8), NL(AD8)ΔVpu or mock infected at 3 and 5 dpi. Similar results have been observed in at least three independent experiments using DCs from different donors.
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Figure 7: HIV-1 replication in iDCs upregulates tetherin independently of Vpu. (A) Supernatants from DCs infected with WT HIV-1 NL(AD8) or NL(AD8)ΔVpu were assessed for p24 concentration to quantify HIV-1 release. Cell lysates from iDC (B), mDC-LPS (C), and mDC-IFNα (D) infected with HIV-1 or mock infected were detected by immunoblotting for the expression of HIV-1 Gag (p55 and p24), tetherin, and GAPDH at 2 h, 3, 5 and 7 days post-infection (dpi). M, mock infection; W, WT NL(AD8); Δ, NL(AD8)ΔVpu. (E) Flow cytometry analyses of cell surface tetherin expression in iDCs infected with WT NL(AD8), NL(AD8)ΔVpu or mock infected at 3 and 5 dpi. Similar results have been observed in at least three independent experiments using DCs from different donors.

Mentions: To examine the role of Vpu and tetherin interactions in HIV-1 infection of DCs, DCs were separately infected with WT NL(AD8) and ΔVpu HIV-1, and viral replication was assessed by p24 production in the supernatants over a time course. There was no significant defect in p24 production from infected iDCs and mDC-IFNα when Vpu was absent (Figure 7A). A 40% decrease of p24 release was observed from mDC-LPS at 7 dpi in the absence of Vpu (Figure 7A), suggesting that Vpu could partially counteract tetherin-mediated restriction of HIV-1 release.


Tetherin does not significantly restrict dendritic cell-mediated HIV-1 transmission and its expression is upregulated by newly synthesized HIV-1 Nef.

Coleman CM, Spearman P, Wu L - Retrovirology (2011)

HIV-1 replication in iDCs upregulates tetherin independently of Vpu. (A) Supernatants from DCs infected with WT HIV-1 NL(AD8) or NL(AD8)ΔVpu were assessed for p24 concentration to quantify HIV-1 release. Cell lysates from iDC (B), mDC-LPS (C), and mDC-IFNα (D) infected with HIV-1 or mock infected were detected by immunoblotting for the expression of HIV-1 Gag (p55 and p24), tetherin, and GAPDH at 2 h, 3, 5 and 7 days post-infection (dpi). M, mock infection; W, WT NL(AD8); Δ, NL(AD8)ΔVpu. (E) Flow cytometry analyses of cell surface tetherin expression in iDCs infected with WT NL(AD8), NL(AD8)ΔVpu or mock infected at 3 and 5 dpi. Similar results have been observed in at least three independent experiments using DCs from different donors.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 7: HIV-1 replication in iDCs upregulates tetherin independently of Vpu. (A) Supernatants from DCs infected with WT HIV-1 NL(AD8) or NL(AD8)ΔVpu were assessed for p24 concentration to quantify HIV-1 release. Cell lysates from iDC (B), mDC-LPS (C), and mDC-IFNα (D) infected with HIV-1 or mock infected were detected by immunoblotting for the expression of HIV-1 Gag (p55 and p24), tetherin, and GAPDH at 2 h, 3, 5 and 7 days post-infection (dpi). M, mock infection; W, WT NL(AD8); Δ, NL(AD8)ΔVpu. (E) Flow cytometry analyses of cell surface tetherin expression in iDCs infected with WT NL(AD8), NL(AD8)ΔVpu or mock infected at 3 and 5 dpi. Similar results have been observed in at least three independent experiments using DCs from different donors.
Mentions: To examine the role of Vpu and tetherin interactions in HIV-1 infection of DCs, DCs were separately infected with WT NL(AD8) and ΔVpu HIV-1, and viral replication was assessed by p24 production in the supernatants over a time course. There was no significant defect in p24 production from infected iDCs and mDC-IFNα when Vpu was absent (Figure 7A). A 40% decrease of p24 release was observed from mDC-LPS at 7 dpi in the absence of Vpu (Figure 7A), suggesting that Vpu could partially counteract tetherin-mediated restriction of HIV-1 release.

Bottom Line: High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs.Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.

ABSTRACT

Background: Dendritic cells (DCs) are among the first cells to encounter HIV-1 and play important roles in viral transmission and pathogenesis. Immature DCs allow productive HIV-1 replication and long-term viral dissemination. The pro-inflammatory factor lipopolysaccharide (LPS) induces DC maturation and enhances the efficiency of DC-mediated HIV-1 transmission. Type I interferon (IFN) partially inhibits HIV-1 replication and cell-cell transmission in CD4+ T cells and macrophages. Tetherin is a type I IFN-inducible restriction factor that blocks HIV-1 release and modulates CD4+ T cell-mediated cell-to-cell transmission of HIV-1. However, the role of type I IFN and tetherin in HIV-1 infection of DCs and DC-mediated viral transmission remains unknown.

Results: We demonstrated that IFN-alpha (IFNα)-induced mature DCs restricted HIV-1 replication and trans-infection of CD4+ T cells. Tetherin expression in monocyte-derived immature DCs was undetectable or very low. High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs. Knockdown of induced tetherin in LPS- or IFNα-matured DCs modestly enhanced HIV-1 transmission to CD4+ T cells, but had no significant effect on wild-type HIV-1 replication in mature DCs. Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.

Conclusions: The restriction of HIV-1 replication and transmission in IFNα-induced mature DCs indicates a potent anti-HIV-1 response; however, high levels of tetherin induced in mature DCs cannot significantly restrict wild-type HIV-1 release and DC-mediated HIV-1 transmission. Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

Show MeSH
Related in: MedlinePlus