HES1 and Epstein-Barr virus infection: Two days post infection, known EBNA2-induced genes CD21 and HES1 [27,40] were not induced by E2KO, but were induced normally by the EBNA-LP mutants (Fig 6B and 6C), suggesting that EBNA-LP does not enhance the transcription of these genes by EBNA2 in the context of EBV infection.