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Galleria mellonella immune response to infection with Streptococcus pyogenes

ABSTRACT: The larvae of Galleria mellonella are increasingly popular as infection model organism to study virulence mechanisms and pathogenicity of bacteria and fungi. In this study, the Streptococcus pyogenes-specific immune response of the larvae was investigated using a proteomics approach. Larvae of the greater wax moth G. mellonella were obtained from Bugs-International GmbH (Irsingen, Germany). The larvae were stored and fed in a wheat bran mixture at 37°C. Larvae with a weight of 0.15 – 0.2 g were used in the experiments. S. pyogenes M49 strain 591 was grown overnight in THY, washed twice in a 0.9% NaCl solution, and suspended in 0.9% NaCl to a final concentration of 2.4 – 4 x 108 CFU/mL. Larvae were infected with 2.4 – 4 x 106 CFU/larva in 10 µL 0.9% NaCl. In each experiment, 45 larvae were infected with S. pyogenes and 30 larvae were injected with 0.9 % NaCl (mock control). Hemolymph was extracted after 4 h, 24 h, and 72 h from 15 infected larvae and 10 non-infected larvae per time point. The hemolymph was separated by centrifugation into cell-free hemolymph and hemocytes. Each experiment was performed in three biological replicates. The protein abundance was regulated in the course of the infection. In the early infection phase, four hours post infection (p.i.), proteins responsible for recognition of foreign surfaces were upregulated, e.g. peptidoglycan recognition proteins. After 24 h, sensory proteins, receptors involved in recognition and opsonisation, and antimicrobial peptides were detected with increased amounts compared to the control group. 72 h p.i., proteins involved in development and metabolism were present at reduced levels. Overall, the immune response of larvae showed relative specificity to S. pyogenes infection, high similarity to the mammalian innate immune response, and a greater complexity than appreciated today.

INSTRUMENT(S):

ORGANISM(S): Galleria Mellonella

TISSUE(S): Hemolymph

DISEASE(S): Disease Free

SUBMITTER: Michael Kreutzer

LAB HEAD: Nadja Patenge

PROVIDER: PXD054400 | Pride | 2025-10-06

REPOSITORIES: Pride

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			Action	DRS
	07022023_Hemocytes.DerivedFromSearchd6dcb455-105f-4e50-a67b-f8a7c77e0b73.mgf	Mgf
	07022023_Hemocytes.mzid.gz	Mzid
	07022023_Hemocytes_10_4_noinf_HDMSe_01.raw.zip	Raw
	07022023_Hemocytes_10_4_noinf_HDMSe_02.raw.zip	Raw
	07022023_Hemocytes_11_4_noinf_HDMSe_01.raw.zip	Raw

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Project description:Streptococcus pyogenes is a major causative agent of tonsillitis or pharyngitis in children, which can lead to more invasive infections and noninfectious sequellae. S. pyogenes can persist in tonsils, while one-third of children treated with antibiotics continue to shed streptococci and have recurrent infections. Mouse nasal-associated lymphoid tissue (NALT) is functionally analogous to human oropharangeal lymphoid tissues. The innate immune responses of naïve cells from a mucosal site to S. pyogenes is not well described; therefore, we infected C57BL/6 mice intranasally with 108 CFU S. pyogenes. Transcriptional responses by NALT after S. pyogenes infection were analyzed by Affymetrix microarray and quantitative RT-PCR. Wild-type S. pyogenes induces transcription of both type I and IFN-gamma-responsive genes, pro-inflammatory genes, and acute phase response plasma proteins within 24h after infection. Invasion of NALT and the induction of the interferon response were not dependent on expression of anti-phagocytic M1 protein. However, infection with an attenuated, less invasive mutant indicated that a robust innate response by NALT is significantly influenced by intra-NALT bacterial load. Granulocytic populations of NALT, cervical lymph nodes and spleen were discriminated by characteristic surface and intracellular markers. Intranasal infection induces systemic release of neutrophils and a substantial influx of neutrophils into NALT at 24h, which decline by 48h after infection. Macrophages do not significantly increase in S. pyogenes-infected NALT. Intranasal infection of IFN-gamma -/- (GKO) C57BL/6 mice did not lead to systemic dissemination of wild type S. pyogenes, despite reduced expression of IFN-gamma-responsive mRNAs in NALT. Infected GKO mice had an unregulated influx of neutrophils into NALT compared to immunocompetant mice and mice treated with an anti-IFN-gamma antibody more rapidly cleared S. pyogenes from NALT. Thus, IFN-gamma-induced responses have a suppressive influence on early clearance of this pathogen from NALT. Keywords: disease state analysis

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Galleria mellonella immune response to infection with Streptococcus pyogenes

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