Multiplicity of Infection

S. T. Abedon*, E. Bartom

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

8 Scopus citations


Multiplicity of infection (MOI) is the ratio of adsorbed, attached, or infecting agents to susceptible targets. This ratio will vary as a function of numbers of infecting agents, how fast those agents attach, how much time is allowed for attachment, and how many targets there are to attach to. Overall, the ratios of infecting agents to targets can be described in terms of Poisson distributions. We discuss three general approaches to MOI determination, arranged in order of increasing precision: estimations based on ratios of agents added to targets (MOIinput), ratios of agents to targets allowing for delays in agent acquisition of targets (MOIactual), and experimental determinations. The conditions under which MOIinput is applicable are fairly narrow, whereas MOIactual, while potentially accurate, should be employed more as an approximation rather than providing high accuracy or precision. Experimental determinations, too, can be prone to error. We additionally discuss an MOI-based means of agent-density determination.

Original languageEnglish (US)
Title of host publicationBrenner's Encyclopedia of Genetics
Subtitle of host publicationSecond Edition
PublisherElsevier Inc
Number of pages2
ISBN (Electronic)9780080961569
ISBN (Print)9780123749840
StatePublished - Feb 27 2013


  • Adsorption
  • Bacteriophage
  • Infection
  • Killing titer
  • Poisson distribution
  • Virus

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Biochemistry, Genetics and Molecular Biology
  • General Medicine


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