Lentiviral MOI & Titre Calculator
Poisson transduction probability and viral stock volumes for a target multiplicity of infection.
How it works
Transduction is modelled as a Poisson process. At multiplicity of infection m, the probability a cell receives at least one viral particle is 1 − e^(−m), which is why an MOI of 1 transduces about 63% of cells rather than all of them. Required virus volume follows from the target MOI, cell number and titre.
Frequently asked questions
What MOI should I use for lentiviral transduction?
For single-copy integration — needed for pooled screens — use an MOI of 0.3 or lower, which transduces roughly 25% of cells and makes multiple integrations per cell unlikely. For simple overexpression or knockdown where copy number does not matter, an MOI of 1–5 gives high transduction. Higher MOI increases toxicity and the chance of confounding multi-copy effects.
Why does an MOI of 1 not transduce every cell?
Viral particles distribute across cells randomly, following a Poisson distribution. At MOI 1 the average cell meets one particle, but by chance some meet none and others meet several. The fraction receiving at least one is 1 − e^(−1), about 63%. Reaching 99% requires an MOI near 5, at which most transduced cells carry multiple integrations.