Analyzing the factors affecting virus invasion by quantitative single-particle analysis

Area of Science:

• Virology
• Cell Biology
• Infectious Diseases

Background:

• Viral diseases pose significant public health threats.
• Understanding viral invasion mechanisms is crucial for developing antiviral strategies.
• Most viruses exhibit low plaque-forming unit (PFU)-to-particle ratios, necessitating investigation into underlying factors.

Purpose of the Study:

• To quantitatively analyze the efficiencies of different stages of viral invasion for Semliki Forest virus (SFV), Japanese encephalitis virus (JEV), and influenza A virus (IAV).
• To identify the rate-limiting steps in the invasion process for each virus.
• To investigate the influence of virus purification methods on invasion efficiency.

Main Methods:

• Quantitative single-particle analysis was employed.
• The study analyzed key invasion steps: attachment, entry, intracellular transport, and endosomal fusion.
• Parallel analysis was conducted for SFV, JEV, and IAV.

Main Results:

• SFV infection was limited by an entry efficiency of approximately 31%.
• JEV infection was limited by attachment (27%) and entry (10%) efficiencies.
• IAV infection was significantly limited by attachment (5%), entry (9%), and fusion (53%) efficiencies.
• Significant variations in attachment efficiencies were observed among the viruses.
• The study also examined the impact of virus purification methods on invasion.

Conclusions:

• Viruses with differing infectivities exhibit distinct rate-limiting steps during invasion.
• Attachment efficiency plays a pivotal role in viral invasion.
• This research provides the first quantitative report on the efficiencies of various viral invasion stages.
• A protocol for quantitatively analyzing virus invasion efficiency has been established.