Tiny giants in a big ocean.

Prasinoviruses infect some of the most abundant photosynthetic eukaryotes in the ocean, shaping microbial dynamics and playing a major role in nutrient cycling. Despite their ecological significance, they have only been explored in a few marine systems. In a recent study, A. B. de Silva, S. W. Polson, C. R. Schvarcz, G. F. Steward, and K. F. Edwards (Microbiol Spectr 13:e02583-24, 2025, https://doi.org/10.1128/spectrum.02583-24) describe four new prasinoviruses isolated from the tropical North Pacific. The comparative analyses highlighted the placement of these viruses within known prasinovirus lineages while also revealing novel genetic features. To assess their ecological reach, the authors mapped metagenomic reads from global data sets, demonstrating that these viruses are not confined to the Pacific but are globally distributed. These findings expand our understanding of prasinovirus diversity and evolution and highlight their widespread occurrence across oceanic regions.