Recent Advances in the Use of Galleria mellonella Model to Study Immune Responses against Human Pathogens

Abstract

The use of invertebrates for in vivo studies in microbiology is well established in the scientific community. Larvae of Galleria mellonella are a widely used model for studying pathogenesis, the efficacy of new antimicrobial compounds, and immune responses. The immune system of G. mellonella larvae is structurally and functionally similar to the innate immune response of mammals, which makes this model suitable for such studies. In this review, cellular responses (hemocytes activity: phagocytosis, nodulation, and encapsulation) and humoral responses (reactions or soluble molecules released in the hemolymph as antimicrobial peptides, melanization, clotting, free radical production, and primary immunization) are discussed, highlighting the use of G. mellonella as a model of immune response to different human pathogenic microorganisms.

Keywords: Galleria mellonella; antimicrobial peptides; clotting; experimental model; free radical production; hemocytes; immune response; in vivo study; melanization; primary immunization.

Figure 1

Schematic representation of G. mellonella immune response. Hemocyte activity links cellular and humoral responses.

Figure 2

Different defense mechanisms employed by hemocytes in Galleria mellonella: (A) nodulation: hemocytes form a layer of cells around a group of microorganisms, this process occurs in the presence of a large number of microorganisms [59]; (B) encapsulation: plasmocytes and granulocytes form a capsule around large pathogens such as protozoa, nematodes and parasitic insect eggs or larvae [76,77,78]; (C) phagocytosis: plasmocytes and granulocytes produce enzymes to destroy the pathogen [1,80].