The use of pseudoviral delivered CRE and floxed reporter
distinguished genes associated with lentiviral reporter expression.
In addition to increased sensitivity for detecting genes associated with
entry when using the CRE reporter, we also found that the use of the CRE
reporter bypassed genes influencing retro-transcription. Specifically,
EP300 was a top hit in both the Spike-mNG and VSVG-mNG screen but not in
the VSVG-CRE screen (Figure 3D and 3E). EP300 is an acetyltransferase
that acetylates HIV-1 integrase to facilitate integration of viral
genome into host genome (Cereseto et al., 2005). In the VSVG-CRE screen,
however, this gene is not detected indicating that direct delivery of
the CRE protein bypassed the steps required for lentiviral reporter
expression. This finding, in conjunction with the strong detection of
LDLR as the known VSV-G receptor, highlights the benefits of using the
CRE to closely link to viral entry with reporter activation without
introducing complexities arising from other viral functions, including
retroviral reporters.