MULTIPLICITY OF INFECTION

(Prepared by: Srushti Bhoite, 20220901003)

                                             Source: https://i.ytimg.com/vi/rfw_rcP5XOA/maxresdefault.jpg

It is defined as the ratio of infectious virions to cells in a culture. When the MOI is high the cell is infected with multiple viruses but when MOI is low the cell is infected with only one virus. In recombining viruses if MOI is higher it would lead to higher recombination and eventually it will lead to more efficient selection, removal of deleterious alleles and emergence of strains with more virulent phenotype.

It may have contrary effects like inferior genotypes are rescued and maintained in population. Complementation at high MOI leads to multiplication of defective particles. High MOI also leads to multiple genomic copies of same gene in one infected cell. In phage if copy number is one it will be lytic and kill the host cell and if it exceeds one it becomes lysogenic and host cell remains alive.

The number of phage infecting each bacterium could be calculated from Poisson equation: P(n) = (m*n × e^-m)/n! where P(n) is the probability that the cell will be infected with exactly “n” phage and “m” is the average number of phage per cell (that is MOI). 

High MOI leads to complex effects on genome selection Distribution of viral particles at different sites of an infection are unknown and will affect MOI and efficiency of selection. The population with highest fitness in the original host does not adapt well in new hosts whereas low frequency genotypes from original host may adapt well in new host. Different types of viruses will be affected differently by MOI.  [1], [2]

     

           Source: https://kb.10xgenomics.com/hc/article_attachments/360043450932/MOI.png

References

[1]      [1]  P. Shabram and E. Aguilar-Cordova, “Multiplicity of infection/multiplicity of confusion,” Molecular Therapy, vol. 2, no. 5. pp. 420–421, 2000. doi: 10.1006/mthe.2000.0212.
[2]  A. Stern and R. Andino, “Viral Evolution: It is All About Mutations,” in Viral Pathogenesis: From Basics to Systems Biology: Third Edition, Elsevier Inc., 2016, pp. 233–240. doi:10.1016/B978-0-12-800964-2.00017-3.