Cells For Inoculum MOI
Solve the target cell count for a specified infectious stock, inoculum volume, dilution, and MOI; physical particles are not substituted for PFU.
Description
Calculate the cell count implied by a PFU inoculum and a target nominal multiplicity of infection.
Multiplicity of infection, or MOI, expresses the input infectious-unit-to-cell ratio for an infection experiment. A nominal MOI describes how much inoculum is applied; the fraction of cells actually infected also depends on adsorption, susceptibility, and the distribution of infectious events.1
Plaque-forming units, or PFU, are assay-defined infectious units rather than a count of physical particles. The tool multiplies a stock PFU concentration by inoculum volume and a dilution fraction to obtain delivered PFU, then divides by the requested MOI.
The dilution fraction is the retained stock concentration: a tenfold dilution is 0.1, not 10. Stock concentration uses PFU/mL, volume uses mL, and target MOI uses PFU per cell. The calculated cell count is left unrounded.
When to use Cells For Inoculum MOI
Use it to check the nominal cell number compatible with an already chosen inoculum, or to compare stock dilution scenarios while holding the target PFU-to-cell ratio fixed.
How to use Cells For Inoculum MOI and interpret its calculation
- Enter nonnegative stockPfuPerMl, positive inoculumVolumeMl, and dilutionFraction from 0 to 1.
- Enter a positive targetMoi and run the calculation.
- Read deliveredPfu and targetCellCount. If an integer cell count is needed, choose a practical count and recalculate the resulting ratio separately.
delivered PFU = stock PFU/mL × volume mL × dilution fraction; target cells = delivered PFU / target MOI Both outputs are nominal quantities based on the supplied plaque titer.
The implementation performs the two arithmetic operations directly. It does not subtract unadsorbed inoculum or infer a Poisson infection fraction.
{
"input": {
"stockPfuPerMl": 1000000,
"inoculumVolumeMl": 0.1,
"dilutionFraction": 0.5,
"targetMoi": 2
},
"output": {
"targetCellCount": 25000,
"deliveredPfu": 50000
}
}Zero stock titer or zero dilution fraction is accepted and returns zero delivered PFU and zero target cells. This is an arithmetic boundary, not a feasible positive-MOI infection well. Zero volume or zero target MOI is rejected.
Limitations and assumptions
The calculation assumes the supplied titer remains applicable after dilution and handling. It does not model losses, adsorption time, target-cell susceptibility, or assay-to-assay titer differences.
A fractional target cell count is possible. No rounding policy, viable-cell correction, infection probability, or uncertainty interval is supplied, and physical particle concentration cannot be substituted for PFU without an appropriate conversion.
Alternative or Complementary methods
Estimate an infectious titer from plaque observations before using it as a concentration input. To relate a target infected-cell fraction to MOI, use a separate model with explicitly stated distribution assumptions.
References
Similar or alternative tools
- Replicate Plaque Assay Titer
Calculate PFU titer from supplied replicate plaque observations.
- Target Transduction MOI
Calculate MOI for a target transduction fraction under its specified model.