To investigate the role of gK/pUL20 in gD and gH/gL localisation in the context of infection, single deletion viruses lacking the expression of functional gK or pUL20 were created by inserting three tandem in-frame stop codons into the genes UL53 (after codon 53), and UL20 (after codon 19) respectively (KOS ΔgK and ΔpUL20; Figure 2). The gene discussed is GK; the disease is infection.