Virus-like Particles (VLPs), derived from viral structural proteins, self-assemble to mimic native virus morphology. VLPs emerged as a robust platform for targeted theranostic applications, owing to their non-infectious, biocompatible and biodegradable nature. Herein, we truncated the N- and C-termini of the Human Papillomavirus type 16 (HPV16) L1 capsid protein to obtain bioengineered, rationally designed VLPs. Truncations in the L1 protein enhanced soluble expression in an Escherichia coli expression system. Purified truncated L1 capsid protein (55 kDa) was conjugated with fluorescent dye (Alexa Fluor 610-X-NHS ester) to generate structurally stable protein with preserved native folding. Truncated protein retained structural integrity even after conjugation and self-assembled into 40-60 nm VLPs in vitro . Internalization of fluorescent VLPs demonstrated that conjugation did not compromise capsid stability/uptake and preserved their morphological and functional integrity in biological environment. Fluorescent VLPs (red fluorescence) were primarily distributed in cytoplasm and frequently clustered in the perinuclear region. Accumulation of VLPs in specific cellular compartments confirmed that these particles mimic native HPV internalization. Furthermore, 3D spatial analysis highlighted their ability to traverse cellular barriers to enter cellular compartments, a feature critical for drug delivery. Taken together, fluorescent VLPs offer promising potential as a next-generation, multifunctional, trackable nanoplatform integrating drug delivery with simultaneous bioimaging for theranostic applications. Such fluorescent viral nano-platforms will facilitate precise drug delivery and real-time tracking within living systems, enabling observation and control over the efficacy of therapeutic interventions.
Kumar et al. (Sat,) studied this question.