How do I determine MOI?

MOI stands for Multiplicity of Infection which refers to the number of viral particles per cell. To calculate, take the number of viral particles used per well then divide by the number of cells originally seeded in the well. This equals the MOI. An MOI of 5 indicates that there are five transducing units for every cell in the well. It is important to note that different cell types may require different MOIs for successful transduction and knockdown of the target gene. For instance, HEK293T cells are highly susceptible to lentiviral transduction (MOI of 5-20) while neuronal cells such as SHSY5Y often require higher MOIs of 10-50.