Deadly winds – Death comes from above

Marine viruses are a key participant in global ocean processes. Viruses are known to infect all forms of cellular life. Hence, they have a significant impact on oceanic nutrient cycles.

The study by Sharoni et al. (2015) focuses on the link between the Emiliania huxleyi virus (EhV) and the common, bloom-forming phytoplankton E. huxleyi in the North Atlantic. Furthermore it examines the dispersal mechanisms. It is shown that aerosolized EhV can be carried on the wind and still be infective.

It is known that virus dispersal can occur in different ways, such as diffusion, mixing, advection, currents and throughout the food web. This paper proves the hypothesis that virus dispersal is not limited to the water body only.

To proof that hypothesis, an aerosolization by wind-induced bubble bursting was simulated in the laboratory. In the first step E. huxleyi was cultivated and infected with EhV. Measuring the concentration of EhV in the air showed that the distribution of EhV in the air grew proportional with the viral production in the water.

To verify that the EhV is still infective, the outflow of the system was linked to another set up with a susceptible strain and a resistant strain of E. huxleyi. As expected, the resistant strain showed no infection whilst the susceptible strain showed viral infection.

In the next step the decay rate of airborne EhV was tested. Using a probable number method (MPN) for calculations of viral infectivity and comparing it to previous studies about the decay rate of viruses it became apparent that EhV can remain infective for several hours.

To compare the results of the laboratory experiment with the natural events, aerosol samples were collected during the E. huxleyi spring bloom in the North Atlantic. Analysis of collected aerosol samples contained virus like particles. Further examination of the DNA signature verified the presumption that the virus like particles was the EhV.

In my opinion the work of Sharoni et al. (2015) contributes to a better understanding of the marine viral dispersal and its impact on oceanic processes. Even though it is known that natural aerosol transmission of viruses is natural, this paper gives a new insight into viral infection and dispersal in the marine environment. For instance to understand the extent of the collapse of E. huxleyi blooms caused by EhV, it is important to know how viral dispersal is working. Not only chemical, physical or biological processes in the water body play a role in the understanding of phytoplankton blooms and their consequences, such as DMSP release caused by viral lysis. Additionally meterological processes and regional climate impacts must be considered for further studies.

Shlomit Sharoni, Miri Trainic, Daniella Schatz, Yoav Lehahn, Michel J. Flores, Kay D. Bidle, Shifra Ben-Dor, Yinon Rudich, Ilan Koren, and Assaf Vardi (2015)

Infection of phytoplankton by aerosolized marine viruses

PNAS 2015 112 (21) 6643-6647;doi:10.1073/pnas.1423667112

http://www.pnas.org/content/112/21/6643.full