Is there any research (including mathematical or computational modelling) regarding how likely it is to infect an organism starting from a single virion entering a single cell?

I am interested in any virus and any multicellular organism (including immunocompromised).


1 Answer 1


This is a great biological question! It asks a lot about how empirical science is done in the field of modern biology! I'm glad we encourage such questions from curious people who want to learn more.

This is called the Independent Action Hypothesis, described here:

The Independent Action Hypothesis (IAH) states that pathogenic individuals (cells, spores, virus particles etc.) behave independently of each other, so that each has an independent probability of causing systemic infection or death.

Zwart et al. (2009) tests this theory, and their results support the hypothesis that a single virus particle can infect a cell:

The ‘independent action hypothesis’ (IAH) states that each pathogen individual has a non-zero probability of causing host death and that pathogen individuals act independently. IAH has not been rigorously tested. In this paper, we (i) develop a probabilistic framework for testing IAH and (ii) demonstrate that, in two out of the six virus–insect pathosystems tested, IAH is supported by the data.

The modeling done in this paper may be worth reviewing.

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    $\begingroup$ See also this paper showing that for influenza in two pigs cages with one contagious it is usually two PFU that caused the infection is the second one, where in a PFU all the virions have (almost) the same genome. The other question is once a viable virus entered the correct cell, what is the probability that it succeeds in finding the right organelles membranes and achieving its replication. The answer is mainly how to translate PFU/ml into number of viruses/ml. $\endgroup$
    – reuns
    Apr 6, 2020 at 10:12

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