INDUCTION KINETICS OF IMMUNE ANTIBACTERIAL PROTEINS IN PUPAE OF GALLERIA-MELLONELLA AND PIERIS-BRASSICAE

1. Pupae of Galleria mellonella and Pieris brassicae given an injectio n with live, non-pathogenic Enterobacter cloacae or abiotic foreign mo lecules induce an acquired immunity that corresponds with the synthesi s of haemolymph proteins of antibacterial activity. 2. This humoral de fensive response which persists for several days, differs quantitative ly between insect species and between the inducers used, although very different foreign bodies induced the same immune proteins in both lep idopteran insects. 3. A stronger and longer lasting response was consi stently noticed in pupae immunized with non-pathogenic bacterium than after sterile nutrient broth injections. 4. A demonstrably elevated ac tivity of haemolymph lysozyme and trace activity of cecropins found in pupae of Galleria treated with saline W, a salt solution physiologica l to moths, disappear soon after 36 hr from injection. 5. In P. brassi cae, however, sterile insect Ringer can give a varying, if present at all, immune response. 6. A mechanical injury (sterile wounding of inse ct body) can occasionally induce a similar but much weaker response. 7 . The antibacterial activity was drastically reduced in Pieris or comp letely depressed in most pupae of Galleria when actinomycin D or cyclo heximide was given at an early time post-immunization with E. cloacae. 8. It is concluded that the de novo synthesis of ribonucleic acid and immune proteins is required for expression of antibacterial activity in pupal haemolymphs. 9. The synthesis of an immune mRNA was completed about 7 hr after the injection of the immunizing bacteria.