Fig 5.

Definition of the stem requirement for inhibition of virus fusion by CHIKV DIII proteins. (A) Alignment of the SFV and CHIKV stem sequences, with the E1 residue numbers indicated above. Below the sequences, “HDIII” indicates the C-terminal boundary of DIII, and the numbers indicate C-terminal residues of the DIII proteins used in panel B. HDIIIS contains the complete stem and is truncated after residue 412 as shown. (B) Inhibition of CHIKV and SFV fusion by CHIKV DIII proteins was monitored by the fusion assay described in Fig. 1. Cells with bound virus were treated at pH 5.5 in the presence of 10 μM the indicated CHIKV DIII protein or the control dengue virus E HDIIIS protein (C). Data were calculated as the percentage of fusion compared to that of the control. Shown are means and standard deviations from 3 independent experiments. Significant differences compared to control samples (P ≤ 0.001) were observed for SFV and CHIKV with 392, 397, and HDIIIS constructs and for CHIKV with the 388 construct.