NECTIN1 and infection: To confirm if HSV1 spreads cell-to-cell in nectin1 KO cells, low multiplicity infections of Wt, ΔgE, ΔgIGFP together with ΔgI were carried out in nTERT and KO cells in the presence of human serum, a well-utilised technique to neutralize extracellularly released virus, thereby eliminating extracellular spread and allowing virus spread only by direct transfer between cells in contact [15].