In order to capture diatom host-virus interactions in a natural diatom assemblage, and as part of the ERC project, we have conducted several targeted field sampling campaigns tracking diatom community dynamics within the spring bloom in the Gulf of Aqaba, Northern Red Sea and additionally, had the opportunity to conduct parallel sampling in the seasonal upwelling plumes in the northeast Pacific. Using a combination of quantitative microeukaryote metatranscriptomics and targeted virus quantification within the peak of a diatom bloom event in the Red Sea, we were able to track dynamic transitions in diatom taxa and corresponding transitions in several distinct RNA viruses, suggesting active virus infection and possibly virus-mediated diatom succession within a single bloom event. To explore these dynamics more broadly and elucidate how viruses interface with diatom communities over environmental gradients, we recently completed a two month-long sampling of the spring bloom in the Red Sea, paired with a series of short-term microcosm, incubation experiments. In parallel, using a combination of physiological, molecular, biogeochemical and 'omics-based techniques, we are working with model diatom and virus isolates in a series of controlled, laboratory-based experiments to better understand how diverse environmental conditions shape host-virus dynamics in diatoms. Since the beginning of the InterDIVE project we found: a) rapid RNA virus population turnover within the aforementioned diatom bloom in the Red Sea, b) unique transcriptomic reprogramming of diatoms infected by RNA viruses, c) a subset of putative biomarker genes and antiviral genes related to RNA virus infection in diatoms and d) a shift in virus life history traits and transient resistance to virus-mediated infection across gradients of macronutrient availability.
