Virus suspensions at the targeted concentrations of salt, protein, and surfactant were prepared right before experiments were conducted. Virus stock and the working solutions were mixed at a ratio of 1:100. Specifically, 50 μL of virus stock was diluted with 4.95 mL of the working solution of interest in 15 mL centrifuge tubes and vortexed for 30 seconds. Virus stock and ultrapure water, which had an initial pH of 5.5, were mixed at the same ratio. The pH of the mixture was adjusted to 4.0, 7.0, or 10.0 with 0.1 M hydrochloric acid or 0.1 M sodium hydroxide and was measured using a pH meter (Orion Versa Star; Thermo). To avoid introducing excessive ions to the mixture, no pH buffer was added after the pH was adjusted to the target value in the mixture. The amount of ions introduced to the solutions to adjust the pH, shown in Table 1, was much lower than that used to make the 1 g/L NaCl working solution. Thus, the change in ionic strength due to pH adjustment should have a negligible effect on virus inactivation.