Responses of Mytilus galloprovincialis to challenge with the emerging marine pathogen Vibrio coralliilyticus

Abstract

Vibrio coralliilyticus (V.c.) has emerged as a coral pathogen of concern throughout the Indo-Pacific reef. The interest towards understanding its ecology and pathogenic potential has increased since V.c. was shown to be strongly virulent also for other species; in particular, it represents a serious threat for bivalve aquaculture, being one of the most important emerging pathogen responsible for oyster larval mortalities worldwide. V.c. has a tightly regulated temperature-dependent virulence and it has been related to mass mortalities events of benthic invertebrates also in the temperate northwestern Mediterranean Sea. However, no data are available on the effects of V.c. in the mussel Mytilus galloprovincialis, the most abundant aquacultured species in this area. In this work, responses of M. galloprovincialis to challenge with V.c. (ATCC BAA-450) were investigated. In vitro, short term responses of mussel hemocytes were evaluated in terms of lysosomal membrane stability, bactericidal activity, lysozyme release, ROS and NO production, and ultrastructural changes, evaluated by TEM. In vivo, hemolymph parameters were measured in mussels challenged with V.c. at 24h p.i. Moreover, the effects of V.c. on mussel early embryo development (at 48 hpf) were evaluated. The results show that both in vitro and in vivo, mussels were unable to activate immune response towards V.c., and that challenge mainly induced lysosomal stress in the hemocytes. Moreover, V.c. showed a strong and concentration-dependent embryotoxicity. Overall, the results indicate that, although M. galloprovincialis is considered a resistant species to vibrio infections, the emerging pathogen V.c. can represent a potential threat to mussel aquaculture.

Mechanistic molecular responses of the giant clam Tridacna crocea to Vibrio coralliilyticus challenge

“…In a global warming scenario, an increase in the seawater temperature could promote the potential disease outbreaks associated with V. coralliilyticus in mollusks [44]. In the present study, we demonstrated that V. coralliilyticus could cause acute mortalities of adult T. crocea when previous work was mainly focused on mortalities of shellfish larvae caused by V. coralliilyticus [12,45].…”

Temperature elevation and Vibrio cyclitrophicus infection reduce the diversity of haemolymph microbiome of the mussel Mytilus coruscus

“…V . coralliilyticus has been reported as a threat to mass mortality of bivalve associated with vibriosis outbreaks 22 . Vibriosis infection events frequently occurred in larval rearing stage of shellfish production hatcheries in the United States, Canada and Mexico, leading to shortages in seed oysters 23,24 .…”

The evolution of the metazoan Toll receptor family and its expression during protostome development

“…Immune roles of the TLRs during ontogeny should not be underestimated: Many marine invertebrate embryos and larvae live in environments rich in microbial pathogens [132,133]. Pathogens cause mortality of embryos and larvae but also provoke anomalies during development [134,135]. Therefore, these embryos and larvae need immune defenses to ght pathogens [133].…”