Overview of the recombinant bacmids used in this study. Two SeMNPV WT (G25 WT and SeBac10 WT) viruses were used: G25 WT is a naturally occurring strain and SeBac10 WT is a bacmid derived from the SeMNPV US1 strain. Using the SeBac10 WT bacmid, two SeMNPV mutants (Δegt-ORF and Δegt-ATG) were made: in Δegt-ORF, a major part of the egt ORF was replaced by a fragment containing a mutant loxP site (used to create the deletion); in Δegt-ATG, only the start codon was replaced by the fragment with the loxP site. An egt-repair bacmid was also constructed. For all bacmid-derived viruses (which lack the original polyhedrin gene), the Se-polh gene and a gentamicin resistance gene (Gm R) were inserted into the genomes between the left and right insertion sites, indicated as Tn7L and Tn7R, present in the bacmid. Positions of neighbouring genes (ptp2: protein tyrosine phosphatase 2 and ORF28) of egt are indicated.