Fig. 4.

Y box binding protein-1 is an essential host-required factor.

(a and b) CD4⁺ T cells were transfected with 300 nmol/l of a negative control small interfering RNA (siRNA), siRNA against Signal Transducer and Activator of Transcription-1 (STAT-1), Myxovirus Resistance Protein-1 (MX-1), WARS, or Y box binding protein-1 (YB-1), and then infected with pseudotyped HIV (HIV-LUC-V). The infected cells were cultured for 48 h, and then luciferase activity was measured. The results show means ± standard errors from three independent assay. (c) CD4⁺ T cells were transfected with a negative control siRNA or a siRNA against Y box binding protein-1, and the expression of Y box binding protein-1 protein in each cell was compared by western blot. (d and e) The siRNA-transfected CD4⁺ T cells were infected with VSV-G-pseudotyped HIV-luciferase virus. HIV reverse transcription products [the early reverse transcription product (R-U5) and the late reverse transcription product (U5-Gag)] in each cell were quantitated by real-time PCR.