Ultimately, both Merlin-RL13tetO-UL74stop and Merlin-RL13tetO-UL128stop formed foci of infected cells, whereas the dual mutants yielded only single-standing infected cells that expressed IE antigens and late antigens but could not spread the infection, indicated by lack of IE antigens in neighbouring cells (Fig. 5b). The gene discussed is NF2; the disease is infection.