One Step Burst Yield

Estimate background-subtracted infectious progeny per infected cell from a single-step growth plateau.

Description

Subtract baseline infectious titer from a growth plateau and divide the net yield by infected cells on the same volume basis.

A one-step growth experiment can summarize infectious output after a defined infection period. Burst yield describes progeny per infected cell, while rise timing describes when production becomes observable. Those quantities require different measurements and should retain the experimental conditions that define them.^[1]

Plaque-forming units, or PFU, quantify plaque-forming infectivity under the assay conditions. A plateau titer can include infectious background remaining from the inoculum. Subtracting a supplied baseline estimates net progeny PFU before dividing by the density of infected cells.

One Step Burst Yield returns net progeny PFU/mL and PFU per infected cell. Numerator and denominator use the same milliliter basis, allowing the volume unit to cancel.

When to estimate background-subtracted infectious yield

Use the tool after selecting a suitable plateau and measuring or estimating the infectious baseline and infected-cell density. Put all measurements on a consistent volume basis before entry.

Separate infectious background from a plateau PFU measurement.
Calculate average PFU yield per infected cell.
Compare calculations from matched experiments while preserving assay and cell-density definitions.

How to enter plateau data and calculate burst yield

Enter nonnegative Plateau pfu per ml and Baseline pfu per ml, with plateau at least as large as baseline.
Enter positive Infected cells per ml for the infected population on the same volume basis.
Run the calculation and read Net progeny pfu per ml and Burst pfu per infected cell.
Retain the plateau time, baseline definition, infection design, and infectivity assay with the result.

netProgenyPfuPerMl = plateauPfuPerMl − baselinePfuPerMl; burstPfuPerInfectedCell = netProgenyPfuPerMl/infectedCellsPerMl

The implementation subtracts the baseline directly and divides by the supplied density. It neither estimates the infected fraction nor rounds the result to whole particles.

json

{
  "input": {
    "plateauPfuPerMl": 1100,
    "baselinePfuPerMl": 100,
    "infectedCellsPerMl": 10
  },
  "output": {
    "netProgenyPfuPerMl": 1000,
    "burstPfuPerInfectedCell": 100
  }
}

Equal plateau and baseline return zero net yield and zero burst yield. A plateau below baseline is rejected rather than clipped to zero. Positive fractional cell densities are accepted because the input is a density, not an integer cell count. Zero infected-cell density and invalid numeric inputs produce errors.

Limitations of an average infectious burst estimate

PFU measure infectious assay output, not physical particle production or genome-copy yield.
The denominator must represent infected cells. Using all exposed cells without an infected-fraction correction changes the result.
No single-cycle design, cell lysis, reinfection, plateau selection, or baseline comparability is verified.
The quotient gives an average with no uncertainty interval or distribution of individual-cell burst sizes. Different measurement volumes require prior normalization.

Alternative or Complementary titer and onset calculations

Calculate plaque titers from counts, dilutions, and inoculated volumes before using them as baseline or plateau inputs. Inspect a time series separately when the first sampled rise is also needed; a plateau quotient contains no timing information.

References

The Growth of Bacteriophage — Journal of General Physiology; E. L. Ellis and M. Delbrück (1939)

Similar or alternative tools

Replicate Plaque Assay Titer
Calculate per-plate and pooled PFU/mL for baseline or plateau plaque measurements.
One Step Rise Onset
Locate the first sampled titer at or above a supplied baseline-fold threshold.