multiplicity of infection

multiplicity of infection

The ratio of viral or phage particles to cells in a system to infection targets (e.g., cells in a defined volume).

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multiplicity of infection (MOI)

(virology) the ratio of infectious virus particles to susceptible CELLS. A high MOI indicates that a lot of virus particles (VIRIONS) are present in the system, relative to susceptible cells.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005