Survival rate is too high in Jurkat transduced with lentivirus

[Camilla Bragonzi]

Hi everyone, 

I am experiencing a very high survival rate when using Jurkat (suspension leukemia T cell line) for CRISPR screening using 3rd generation lentivirus. 

I calculated the MOI (=0.3) to use by a titration in a 12 well plate, and I am now performing the screening in T175 flasks. 

The issue is that differently to plates, in flasks the cell survival (with the same lentiviral dilution) is much higher, making me question about the number of integrants per cell. 

My hypothesis are these: 

1. cell transduction efficiency is somehow higher in flasks compared to plates, so more cells get transduced/cells get transduced with more than an integrant. 

2. cell transduction efficiency is the same, but Jurkat multiplication rate in flasks is higher

There might of course be other reasons that didn't come to my mind. 

Does anyone have some or similar experiences, and how did you solve this problem? 

Any suggestions are welcome!!! 

Many thanks, 

Camilla