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. 2024 Jan 5;34(2):140–150. doi: 10.1038/s41422-023-00917-w

Fig. 3. LDLR is essential for CCHFV binding to cells.

Fig. 3

a Effects of LDLR on CCHFV attachment and internalization. The control (gNC), LDLR-deficient (gLDLR-C1) or LDLRAP1-deficient (gLDLRAP1) SW13 cells were incubated with CCHFV at 4 °C for 1 h (for binding assay), or followed with incubation at 37 °C for 1 h (for internalization assay). The cells were collected and CCHFV S mRNA level was measured by RT-qPCR. Data are normalized to the CCHFV S mRNA level in the control gRNA-edited cells. b Effects of LDLR blocking antibodies on CCHFV infection. SW13, Huh7, Vero E6, primary human PBMCs and HUVECs, and mouse Hepa1-6 cells were pre-incubated with a rabbit anti-hLDLR mAb (R301), a goat anti-hLDLR pAb (#AF2148), a rabbit anti-mLDLR mAb (R004), or their respective control IgGs as indicated for 1 h before CCHFV infection (MOI = 0.05). Twenty-four hours after infection, the cells were collected for RT-qPCR analysis for CCHFV S mRNA level. Data are normalized to that of cells treated with the respective control IgG at 0 μg/mL. c Effects of LDLR blocking antibodies on the entry of RVFV, EBIV and VSV. SW13 cells were pre-incubated with the indicated concentrations of a control rIgG or a rabbit anti-hLDLR mAb (R301) for 1 h before infection RVFV, EBIV or VSV. Twenty-four hours after infection, mRNA levels of RVFV M segment, EBIV S segment, or VSV L gene were measured by RT-qPCR analysis. Data are normalized to that of cells treated with the respective control IgG at 0 μg/mL. d LDL inhibits CCHFV infection. SW13 cells (left) and HUVEC cells (right) were pre-treated with the indicated concentrations of LDL for 1 h and then left uninfected or infected with CCHFV (MOI = 0.05). Twenty-four hours post infection, CCHFV S mRNA level was analyzed by RT-qPCR. Data are normalized to that of CCHFV infected cells without LDL treatment. e The soluble human LDLR-Fc fustion protein (sohLDLR-Fc) inhibits CCHFV infection. CCHFV (MOI = 0.05) was pre-incubated with the indicated concentrations of Fc or sohLDLR-Fc for 1 h before infection of SW13 and Huh7 cells. Twenty-four hours post infection, CCHFV S mRNA level was analyzed by RT-qPCR. Data are normalized to that of cells infected with un-pretreated viruses. f Effects of sohLDLR-Fc on RVFV, EBIV and VSV infection in SW13 cells. RVFV (MOI = 0.1), EBIV (MOI = 0.5) or VSV (MOI = 0.1) were pre-incubated with the indicated concentrations of sohLDLR-Fc or Fc for 1 h before infection of SW13 cells. Twenty-four hours post infection, mRNA levels of RVFV M segment, EBIV S segment, or VSV L gene were measured by RT-qPCR analysis. Data are normalized to that of cells infected with the respective un-pretreated viruses. Data are represented as mean ± SD. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.