Infection with axenic nematodes for 12 h strongly downregulated the genes CG34424 (5-formyltetrahydrofolate cyclo-ligase), CG13071 (unknown), CG33264 (Or69a), CG31748 (Gr36c), whereas infection with symbiotic nematodes mostly downregulated genes with unknown function such as CG43184, CG7327, CG8960 and CG42755. Similarly, Photorhabdus infection caused downregulation of several unknown genes, such as CG13427, CG42367 (insect cuticular protein) and CG13711. A complete list of the 25 most strongly downregulated genes upon infection with the two pathogens is shown in Additional file 1: Figure S5. This evidence concerns the gene MTHFS and infection.