A newly discovered viral particle known as PelV-1 possesses the longest tail ever observed on a virus, measuring an astonishing 2.3 micrometers. This giant virus was found infecting dinoflagellate plankton in the Pacific Ocean and uses its elongated tail to attach itself to its host while injecting its genetic material. Researchers from Cornell University, led by oceanographer Andrian Gajigan, suggest that this remarkable appendage may also assist the virus in locating its often sparsely distributed hosts, the Pelagodinium plankton, which inhabit the upper layers of ocean waters.
The discovery of PelV-1 is significant, as it surpasses the tail length of previously known viruses. Most viral tails measure in nanometers, but PelV-1’s tail exceeds the 875 nanometers of the longest known phage, P74-26, which infects Thermus thermophilus. Another giant virus, Tupanvirus, has a tail ranging from 0.55 to 1.85 micrometers. Gajigan and his team noted that while PelV-1’s tail is considerably longer, the ratio between its tail and head mirrors that of P74-26. They questioned whether this similarity is coincidental or if an underlying mechanism dictates this ratio across different virus taxa.
Since the initial discovery of giant viruses in 2003, these entities have continuously defied expectations. Some are larger than bacteria, while others reveal insights into cellular structures and challenge the definitions of life. Dinoflagellates, the primary hosts for PelV-1, play a crucial role in global ecosystems. They are vital for producing oxygen and cycling essential nutrients like carbon throughout the planet. Additionally, these organisms can trigger harmful algal blooms, which adversely affect aquatic environments and the species that depend on them, including wildlife and fisheries.
Despite the significance of viruses in dinoflagellate ecology, the understanding of their influence remains limited. Gajigan’s team pointed out that only a handful of viruses have been isolated from plankton so far, indicating a wealth of undiscovered viral diversity yet to be explored. The research findings, which are still awaiting peer review, have been made available on the preprint platform bioRxiv.
As investigations into the interactions between these giant viruses and their hosts continue, further discoveries may reshape our understanding of marine ecosystems and the intricate relationships within them.
