CELLULAR DEFENSE IN AN ARTHROPOD IN RESPONSE TO INFECTION WITH A SALMONELLA TYPHIMURIUM STRAIN

Larvae of Galleria mellonella L. when injected with cells of Salmonella typhimurium strain LT 2 responded by cellular defense: their hemocytes gathered and formed a pseudo-tissue by which the bacteria were encapsulated. In contrast, S. typhimurium strain 7 Suc LL caused lysis of about 64% of the hemocytes and cellular defense against this strain was lacking. This explains the difference in the mortality rate of the larvae which was 10% after intracoelomic injection with 2×104 cells of strain LT 2 and 48% with the same number of cells of strain 7 Suc LL. After injection of strain 7 Suc LL, lysis of hemocytes preceded proliferation of bacteria; moreover such lysis also occurred after injection of cell-free culture filtrate of this strain. This suggests that lysis is due to either a toxic substance or a proteolytic enzyme produced by strain 7 Suc LL. © 1969 Swets & Zeitlinger.