Test your viral titers to obtain correct MOI in cell culture

Irene Ramos
07/27/2018

Multiplicity of infection in virology

In virology, researchers very often need to calculate the multiplicity of infection (MOI) for cell culture experiments, which refers to the number of infectious particles to be added per cell. The concentration of infectious particles in a virus stock is frequently calculated in standard cell types, but sometimes the infectivity varies between those cells and the cell type we want to study, leading to different effective MOIs in the experiments.

Click this link to learn more about MOIs in virology

How this app can help virologists test MOIs?

With this app, you can evaluate if your MOI calculations lead to the expected percentage of infected cells in your cell type of interest according to the poisson distribution (plotted in blue), and adjust the virus dose accordingly.

You just need to type in the left panel the MOIs that you are testing and the experimental percentage of infected cells that you obtain (by flow cytometry or immunofluorescence, for example), which will be plotted in red. You can include up to 5 data pairs.

In this example, the experimental MOI showed lower percentage of infected cells than expected, so it could be adjusted by increasing the virus dose:

-pair 1: 0.2, 5 (0.2 MOI gives 5% of infected cells);
-pair 2: 0.5, 20;
-pair 3: 1, 40;
-pair 4: 3, 70;
-pair 5: 10, 90

plot of chunk unnamed-chunk-1

In this second example, we can see the opposite scenario. The experimental MOI showed higher percentage of infected cells than expected, so it could be adjusted by lowering the virus dose:

-pair 1: 0.2, 40 (0.2 MOI gives 40% of infected cells);
-pair 2: 0.5, 80;
-pair 3: 1, 97;
-pair 4: 3, 99;
-pair 5: 10, 100

plot of chunk unnamed-chunk-2