Nathan MORANDI

The VIRPAV Project

Viruses infesting phytoplanktonic algae are known to trigger and/or accelerate the end of blooms of these algae in the wild (Flynn et al. 2022). Knowledge of these viruses is very patchy, and their diversitý seems to be more extensive than imagined even a few years ago. In addition to the host-virus specificitý which has not been proven, the infestation mechanisms and modes of action of the viruses remain very poorly documented. Recent observations (Véron et al. 2023) highlight the presence of viral particles in cells within a new group of algae, the Pavlovophyceae, previously deemed uninfested by viruses (Sandaa et al. 2022). These unicellular algae are cultivated for feeding young larval stages of molluscs (Ponis et al. 2006a,b). Biomass production crops can also be used to extract molecules of interest, but it is rarely possible to maintain a stationary phase of growth over periods of several months, forcing professionals to rotate crops discontinuously and ultimately leading to erratic production, resulting in higher costs and production uncertainties. Furthermore, correlations are beginning to emerge between warming water masses and viral infestation of phytoplankton cells. This last point remains to be linked to the revealed effects of global warming on marine viruses (Danovaro et al. 2011, Demory et al. 2017).