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. 2018 Aug 7;10(8):413. doi: 10.3390/v10080413

Figure 1.

Figure 1

Ectopic expression of IFITM proteins inhibits entry of HIV-1 CXCR4 (X4) and CCR5 (R5) strains at equivalent efficiency independent of co-receptor usage. (A) FLAG-tagged IFITM1, 2, 3 expression levels in U87.CD4.CXCR4 and U87.CD4.CCR5 stable cell lines were examined by immunoblotting using an anti-FLAG antibody. β-actin served as loading control. (B,C) One-round pLenti-GFP HIV-1 infection assay was performed by infecting indicated cells with pLenti-GFP pseudotypes bearing Env of interest and percentages of GFP+ cells were quantified by flow cytometry. Relative entry efficiency was calculated by comparing the percentages of HIV-1 GFP+ cells expressing IFITMs with that of pQCXIH vector controls. Note that CXCR4 tropic viruses NL4.3 and HXB2 and dual tropic virus 89.6 were examined in U87.CD4.CXCR4 cells (B); CCR5 tropic viruses AD8 and JRFL and dual tropic 89.6 were examined in U87.CD4.CCR5 cells (C). (D,E) Single-round infection of HIV-1 NL4.3, AD8 and 89.6 and MLV 10A1 was measured by using HIV-inGLuc reporter pseudotypes in U87.CD4.CXCR4 (D) or U87.CD4.CCR5 cells (E). See detailed methods in the text. All data are presented as mean ± SD of at least three independent experiments; * p < 0.05, ** p < 0.01, *** p < 0.001.