Efficient compartmentalization in insect bacteriomes protects symbiotic bacteria from host immune system

Area of Science:

• Insect-microbe interactions
• Innate immunity
• Symbiosis

Background:

• Insects host symbiotic bacteria (endosymbionts) in specialized bacteriomes for nutrient acquisition.
• Bacteriome immunity can be activated against pathogens, potentially impacting endosymbionts.
• Understanding endosymbiont protection during immune challenges is crucial.

Purpose of the Study:

• To investigate molecular determinants of endosymbiont protection during immune challenges.
• To analyze the transcriptomic response of the bacteriome to immunogenic stimuli.

Main Methods:

• Dual transcriptomic analysis of the cereal weevil Sitophilus oryzae bacteriome.
• Exposure to immunogenic peptidoglycan fragments to simulate an immune challenge.
• Immunohistochemistry to localize antimicrobial peptides.

Main Results:

• The bacteriome mounts an innate immune response, inducing antimicrobial peptides (AMPs).
• Endosymbionts show no transcriptomic changes, indicating they are unaffected by the immune response.
• Induced AMPs are localized outside the bacteriome, preventing contact with endosymbionts.

Conclusions:

• Endosymbiont protection relies on physical confinement within bacteriomes.
• Bacteriomes provide a barrier, separating the host's systemic immune response from endosymbionts.
• Efficient bacteriome structure ensures endosymbiont survival during host immune activation.