Functional and molecular immune response of Mediterranean mussel (Mytilus galloprovincialis) haemocytes against...

Area of Science:

• Immunology
• Marine Biology
• Microbiology

Background:

• Immune responses in aquatic organisms are crucial for survival.
• Pathogen-associated molecular patterns (PAMPs) are key triggers of innate immunity.
• Understanding immune modulation by bacteria and PAMPs is vital for aquaculture and disease management.

Purpose of the Study:

• To investigate the effects of live bacteria and various PAMPs on immune parameters in vitro and in vivo.
• To analyze the production of toxic radicals and gene expression of antimicrobial peptides and lysozyme.
• To compare the immune responses induced by different bacterial species and PAMPs.

Main Methods:

• In vitro and in vivo experiments using haemocytes.
• Measurement of respiratory burst activity and nitric oxide production.
• Analysis of mytilin B, myticin C, and lysozyme gene expression.
• Exposure to live bacteria (Micrococcus lysodeikticus, Vibrio anguillarum) and PAMPs (poly I:C, zymosan, LPS, LTA, CpG).

Main Results:

• Bacteria significantly increased haemocyte respiratory burst activity and nitric oxide production.
• In vivo responses to M. lysodeikticus were faster than V. anguillarum, but V. anguillarum induced stronger in vitro effects.
• LPS elicited the highest immune response among all tested PAMPs.
• Antimicrobial peptide and lysozyme gene expression peaked at 3 hours post-infection.

Conclusions:

• Live bacteria and PAMPs effectively modulate immune responses in aquatic organisms.
• Different bacterial species and PAMPs activate distinct signaling pathways.
• LPS is a potent immune stimulant, and its role in aquatic immunity warrants further investigation.
• Early induction of antimicrobial peptides and lysozyme suggests rapid defense mechanisms.