How do you determine titer?

There is a titering protocol in the GIPZ, TRIPZ, Precision LentiORF and Trans-Lentiviral Packaging System technical manuals for titering virus intended for customers who make their own virus (Protocol – Titering). There is also a protocol for determining relative transduction efficiency (Protocol – Determining Relative Transduction Efficiency). This is for customers who know the titer in HEK293T - either because the virus was purchased from us or because the customer titered it themselves in HEK293T cells and want to figure out how much virus to use in another cell line.