Bactericidal Activity of the Blood of Actively Immunized Wax Moth Larvae

Abstract

The blood of normal wax moth larvae is not bactericidal for Pseudonzo?tas aerzrginosa. The blood becomes moderately bactericidal when larvae are actively immunized against P. aerzrginosa. This activity was measured b y a modification of Nagington's technique for the estimation of typhoid antibody. Bactericidal activity appears t o be the only measurable type of antibody response against P. aerrrginosa. Cell-free blood was as active as whole blood; 0.02 ml of immune serum kills about 1000 organisms. The blood of normal wax moth larvae is bactericidal for Shigella dysenteriue but the blood of insects immunized against either this organism or P . aerrrginosa shows no increase in activity against S . dysenteriae. A number of non-specific agents, both protein and non-protein, did not stimulate bactericidal activity in serum after their injection into normal larvae. Immune sera prepared against some strains of P. aeruginosa were not active against other strains. Storage a t 37' C or absorption with zymosan both result in blackening of immune blood and loss of bactericidal activity. Bactericidal activity is evident only during the immune state of the insect, i.e. from about 18 hours until the third day after vaccination; it develops a t the same time that inhibition of melanization was observed in the blood from vaccinated larvae.

Prior infection of Manduca sexta with non-pathogenic Escherichia coli elicits immunity to pathogenic Photorhabdus luminescens: Roles of immune-related proteins shown by RNA interference

“…1). Reduced susceptibility to Photorhabdus appeared rapidly, within a few hours, and persisted for at least 48 h. This is consistent with previous observations (Stephens, 1959(Stephens, , 1962 in which immunity was induced within hours of exposure to microbial pattern molecules. There was no sign in our experiments of any decline in immunity during the 48 h period of the experiment.…”

“…We considered it inappropriate to extend the duration of the experiment beyond this time, because at later times the control insects would be preparing to pupate, when new immune defences begin to appear according to a developmental programme (Dunn et al, 1994). In previous work with Galleria mellonella larvae (Stephens, 1959(Stephens, , 1962 immunity induced by injection of killed P. aeruginosa cells was found to decline after about 24 h. The possibility that the progressive loss of immunity with time seen in Stephens' experiment was due to the onset of pupation cannot be excluded. Further work is required to define more precisely the duration of the protection afforded by pre-infection.…”

“…Given that the induced immunity to infection of preinfected insects has long been known to be accompanied by the presence of microbicidal activity in haemolymph (Stephens, 1962) and that insects are now known to secrete both recognition proteins and antimicrobial effectors into the haemolymph (Kanost et al, 2004), we examined the rate of growth of the Photorhabdus pathogen in the cell-free plasma of haemolymph bled from treated insects. The results (Fig.…”

“…But it has been recognised for many years that 'immunisation' with killed bacteria (e.g. with Pseudomonas aeruginosa -Stephens, 1959-Stephens, , 1962 or prior infection with living bacteria (e.g. with Enterobacter cloacae- Boman et al, 1972Boman et al, , 1974 can induce in insects a temporary state of markedly enhanced resistance to subsequent infection, either to the same bacterium or a different one.…”

Reactions of Tenebrio molitor and Galleria mellonella to MS2 bacteriophage and Pseudomonas aeruginosa

“…Since Stephens (46,47) had reported that immunization was accompanied by a loss of the ability of the hemolymph to melanize I decided to see if rnelanization times could be used as an index of immunity. This should be possible if the inverse relationship described by Stephens (46,47) and by Taylor (49) is a result of immunization.…”