Apparent cooperativity between human CMV virions introduces errors in conventional methods of calculating multiplicity of infection.

Apparent cooperativity between human CMV virions causes overestimation of infection rates, challenging traditional methods of calculating multiplicity of infection.

• Why it matters: Understanding whether virions infect cells independently or cooperatively is crucial for accurate virus quantification and infection modeling, impacting disease research and treatment strategies.
• What they did: The study titrated three HCMV strains on fibroblasts and epithelial cells, using flow cytometry to measure infection frequency across various inoculum concentrations, and employed mathematical and stochastic models to analyze cooperativity.
• The result: Findings reveal that apparent cooperativity arises from factors beyond virion heterogeneity or aggregation, emphasizing the need for refined methods to accurately assess infection dynamics and multiplicity of infection.