Fig 3.

Cross-species inhibition of virus membrane fusion by CHIKV and SFV DIII proteins. Serial dilutions of CHIKV, SFV, or SINV were prebound to BHK cells on ice, and virus fusion was triggered by treatment at 37°C for 1 min at the optimal pH value determined for each virus in Fig. 1 (SFV/CHIKV, pH 5. 5; SINV, pH 5.0). The indicated concentrations of exogenous CHIK or SFV DIII proteins without (A) or with (B) the stem region were included during the 1-min low-pH treatment. Results are expressed as the percentage of fusion in the absence of any added DIII protein. Shown are means and standard deviations from 3 independent experiments.