Double stranded RNA is processed differently in two oyster species

Area of Science:

• * Marine biology
• * Immunology
• * Oyster aquaculture

Background:

• * Ostreid herpesvirus causes significant mortality in Pacific oysters (Crassostrea gigas) but not Sydney Rock Oysters (Saccostrea glomerata).
• * Double-stranded RNA (dsRNA) can mimic viral infections and trigger innate immune responses via Toll-like receptors, leading to interferon and cytokine production.
• * Understanding differential immune responses is crucial for managing oyster diseases and improving aquaculture sustainability.

Purpose of the Study:

• * To investigate the differences in dsRNA uptake, processing, and immune response between *C. gigas* and *S. glomerata*.
• * To identify specific tissues involved in dsRNA recognition and immune activation in oysters.
• * To elucidate the mechanisms underlying differential susceptibility to Ostreid herpesvirus.

Main Methods:

• * Injection of fluorochrome-labeled poly (I:C) dsRNA into *C. gigas* and *S. glomerata*.
• * Tracking dsRNA uptake and clearance in gill and mantle tissues using fluorescence microscopy.
• * Quantifying immune gene expression (interferon and cytokines) via real-time PCR.

Main Results:

• * Significant differences observed in dsRNA tissue uptake and clearance rates between the two oyster species.
• * *S. glomerata* demonstrated more efficient dsRNA processing compared to *C. gigas*.
• * Gill tissue identified as a primary site for dsRNA processing and immune response activation in both species, with differential activity observed.

Conclusions:

• * *S. glomerata* possesses a more robust innate immune response to dsRNA compared to *C. gigas*, contributing to its resistance against Ostreid herpesvirus.
• * Gill tissue plays a critical role in initiating antiviral immune responses in oysters.
• * These findings provide insights into species-specific disease resistance mechanisms and inform strategies for oyster health management.