Symbionts shape host innate immunity in honeybees

Area of Science:

• Microbiology
• Immunology
• Animal Science

Background:

• The honeybee gut microbiome is crucial for host health, influencing nutrition and immunity.
• The interaction between honeybee immune systems and gut symbionts remains largely unexplored.
• Understanding these interactions is vital for bee health and colony survival.

Purpose of the Study:

• To investigate how the gut symbiont Snodgrassella alvi influences honeybee immune gene expression.
• To determine the protective effects of S. alvi against the pathogen Serratia marcescens.
• To elucidate the specific immune pathways modulated by S. alvi colonization.

Main Methods:

• Exposure of honeybees to live and heat-killed S. alvi.
• Analysis of honeybee immune gene expression, focusing on antimicrobial peptides.
• Comparison of immune responses mediated by the Toll and Imd pathways.
• Assessment of S. marcescens load in honeybee guts post-treatment.

Main Results:

• Both live and heat-killed S. alvi conferred protection against S. marcescens.
• S. alvi induced the expression of host antimicrobial peptides.
• Heat-killed S. alvi elicited a more pronounced immune gene expression response than live S. alvi.
• The Toll pathway was preferentially upregulated over the Imd pathway by S. alvi.
• Live S. alvi facilitated the clearance of S. marcescens from the honeybee gut.

Conclusions:

• Colonization by S. alvi triggers a consistent immune response in honeybees.
• This immune response may benefit both the host and symbiont by managing gut microbial populations.
• S. alvi plays a role in colonization resistance, preventing pathogen invasion and overgrowth.