Fig. (3) ThT fluorescence spectra of different NSP4ΔN72 proteins. The figure insert shows the ThT fluorescence spectra of NSP4ΔN72 from the Vellore symptomatic (N136) and asymptomatic (2KD/851) strains and E158K mutant protein generated from N136. Note that the fluorescence spectrum of the mutant protein is identical to that from the asymptomatic strain 2KD/851.