Fluorescence biosensor for real-time interaction dynamics of host proteins with HIV-1 capsid tubes

The human immunodeficiency virus 1 (HIV-1) capsid serves as a binding platform for proteins and small molecules from the host cell that regulate various steps in the virus life cycle. However, there are currently no quantitative methods that use assembled capsid lattices for measuring host-pathogen interaction dynamics. Here we developed a single molecule fluorescence biosensor using self-assembled capsid tubes as biorecognition elements and imaged capsid binders using total internal reflection fluorescence microscopy in a microfluidic setup. The method is highly sensitive in its ability to observe and quantify binding, obtain dissociation constants, extract kinetics with an extended application of using more complex analytes that can accelerate characterisation of novel capsid binders.