What Is MOI? Understanding Multiplicity of Infection

MOI (Multiplicity of Infection) refers to the number of viral particles added per target cell. It is one of the most important parameters in viral transduction experiments.

Why MOI Matters

If the MOI is too low, transduction efficiency may be poor. If it is too high, cells may experience toxicity or unwanted off-target effects. Selecting the right MOI is essential for reproducible results.

How MOI Is Calculated

MOI is typically determined using the viral titer and the number of target cells. Accurate AAV titer measurement or lentivirus quantification is therefore a critical first step.

Experimental Considerations

  • Cell type-specific susceptibility
  • Vector system used
  • Culture conditions
  • Potential cytotoxicity

Conclusion

MOI is not just a calculation. It is a key variable that influences both gene delivery performance and cell health.

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