Rapid actin-dependent viral motility in live cells

Area of Science:

• Cell biology
• Virology
• Biophysics

Background:

• Viruses utilize diverse mechanisms for intracellular transport, including diffusion and active transport along cytoskeletal filaments.
• Studying viral motility in complex cellular environments requires advanced analytical tools.

Purpose of the Study:

• To develop and utilize a novel assay for global, unbiased analysis of viral trajectories within live cells.
• To investigate the motility characteristics of poliovirus within host cells.

Main Methods:

• Development of a high-throughput motility assay for analyzing tens of thousands of virus trajectories in live cells.
• Observation of poliovirus movement in various human-derived cell lines.
• Investigation of the dependence of motility on cellular components like microtubules and actin, as well as energy requirements.

Main Results:

• Poliovirus displays anomalously rapid intracellular movement (up to 5 microm/s), independent of microtubules.
• This rapid motility allows poliovirus to explore most cellular regions, excluding the nucleus.
• The movement is energy-dependent and requires an intact actin cytoskeleton, suggesting active transport.
• This actin-dependent motility is significantly faster than previously reported speeds for actin-based transport in animal cells.
• The motility was specific to poliovirus and not observed in other cargo, including a related picornavirus.

Conclusions:

• Poliovirus employs a unique and exceptionally fast active transport mechanism for intracellular movement.
• This mechanism is actin-dependent but microtubule-independent, distinguishing it from typical cellular cargo transport.
• The rapid motility likely facilitates efficient viral dissemination within the host cell.