DNMT3B and lentivirus infection: To assess the effect of E6 and E7 gene silencing on the protein expression levels of the DNA methyltransferase, we examined the expression of these 4 proteins at 48 and 96 h after lentivirus infection using antibodies specific for DNMT1, DNMT3A, DNMT3B and DNMT3L by immunoblotting.