Physical stress primes the immune response of Galleria mellonella larvae to infection by Candida albicans

Abstract

Larvae of the greater wax moth (Galleria mellonella) that had been subjected to physical stress by shaking in cupped hands for 2 min showed reduced susceptibility to infection by Candida albicans when infected 24 h after the stress event. Physically stressed larvae demonstrated an increase in haemocyte density and elevated mRNA levels of galiomicin and an inducible metalloproteinase inhibitor (IMPI ) but not transferrin or gallerimycin. In contrast, previous work has demonstrated that microbial priming of larvae resulted in the induction of all four genes. Examination of the expression of proteins in the insect haemolymph using 2D electrophoresis and MALDI TOF analysis revealed an increase in the intensity of a number of peptides showing some similarities with proteins associated with the insect immune response to infection. This study demonstrates that non-lethal physical stress primes the immune response of G. mellonella and this is mediated by elevated haemocyte numbers, increased mRNA levels of genes coding for two antimicrobial peptides and the appearance of novel peptides in the haemolymph. This work demonstrates that physical priming increases the insect immune response but the mechanism of this priming is different to that induced by low level exposure to microbial pathogens.

Decreased expression of 14-3-3 inParacoccidioides brasiliensisconfirms its involvement in fungal pathogenesis

“…Several studies have established G. mellonella as a useful model for evaluating fungal virulence, 52-56 including for P. lutzii, another species belonging to the Paracoccidioides species complex, 57 with the advantage that the innate immune response is highly similar between insects and mammals, 58,59 60 including antimicrobial peptides and cells with phagocytic activity in hemolymph that function in a manner similar to human phagocytes. [61][62][63] Decreased expression of Pb14-3-3 resulted in a significant reduction of the virulence phenotype as reflected in the survival curve and CFU experiment with G. mellonella model. There was a reduction in the fungal burden in the larvae infected with the silenced strain, probably due to difficulty in the establishment in the host, leading to a lower resistance to killing by the host's immune system.…”

Effect of nutrient deprivation on the susceptibility ofGalleria mellonellalarvae to infection

“…It has previously been documented that G. mellonella larvae display the ability to alter their immune response when exposed to microbial cell wall components, 11 fungal cells, 12 physical stress 13 or thermal variation. 14 It was postulated that a reduction or elimination of food could also alter the immune response of insects since food provides energy for maintaining homeostasis and immune function.…”

Pre-exposure ofGalleria mellonellalarvae to different doses ofAspergillus fumigatusconidia causes differential activation of cellular and humoral immune responses

“…Prior exposure of larvae of Galleria mellonella to non-lethal doses of yeast cells provokes an immune response, which increases their resistance to a subsequent lethal inoculum. 9 Administration of microbial cell wall components 10 or stress (physical or thermal) 11,12 induce a similar protective response. The elevated immune response subsequent to the initial challenge is mediated by an increase in the hemocyte density and the elevated expression of antimicrobial peptides.…”