The Role of Anti-Viral Effector Molecules in Mollusc Hemolymph.

Molluscs are major contributors to the international and Australian aquaculture industries, however, their immune systems remain poorly understood due to limited access to draft genomes and evidence of divergences from model organisms. As invertebrates, molluscs lack adaptive immune systems or 'memory', and rely solely on innate immunity for antimicrobial defence. Hemolymph, the circulatory fluid of invertebrates, contains hemocytes which secrete effector molecules with immune regulatory functions. Interactions between mollusc effector molecules and bacterial and fungal pathogens have been well documented, however, there is limited knowledge of their roles against viruses, which cause high mortality and significant production losses in these species. Of the major effector molecules, only the direct acting protein dicer-2 and the antimicrobial peptides (AMPs) hemocyanin and myticin-C have shown antiviral activity. A better understanding of these effector molecules may allow for the manipulation of mollusc proteomes to enhance antiviral and overall antimicrobial defence to prevent future outbreaks and minimize economic outbreaks. Moreover, effector molecule research may yield the description and production of novel antimicrobial treatments for a broad host range of animal species.

Immune Control of Herpesvirus Infection in Molluscs.

Molluscan herpesviruses that are capable of infecting economically important species of abalone and oysters have caused significant losses in production due to the high mortality rate of infected animals. Current methods in preventing and controlling herpesviruses in the aquacultural industry are based around biosecurity measures which are impractical and do not contain the virus as farms source their water from oceans. Due to the lack of an adaptive immune system in molluscs, vaccine related therapies are not a viable option; therefore, a novel preventative strategy known as immune priming was recently explored. Immune priming has been shown to provide direct protection in oysters from Ostreid herpesvirus-1, as well as to their progeny through trans-generational immune priming. The mechanisms of these processes are not completely understood, however advancements in the characterisation of the oyster immune response has assisted in formulating potential hypotheses. Limited literature has explored the immune response of abalone infected with Haliotid herpesvirus as well as the potential for immune priming in these species, therefore, more research is required in this area to determine whether this is a practical solution for control of molluscan herpesviruses in an aquaculture setting.