Viruses have dominated the microscopic world of the oceans for billions of years and researchers find it difficult to track and isolate their activities because they are invisible to the naked eye.
But science has finally caught up with these tiny vectors of change, says Marine researcher, Dr Karen Weynburg, a Synthetic Biology Fellow at the CSIRO and the University of Queensland.
“For some people, it’s just not on their radar that viruses are so central to everything in life” Weynburg says.
In the paper: Marine prasinoviruses and their tiny plankton hosts: a review, research led by Weynburg reported viruses co-evolved with their hosts and are immersed in a constant battle of survival to outwit and outplay for control.
“Recently there’s been a discovery that probably what happened was that all life was RNA” Weynburg says. Viruses probably existed before cells, says Weynburg, and were the precursors of life. Viruses switched from RNA to DNA to avoid their genomes being attacked and removed by the host cell.
Viruses are not regarded by science as a real organism because they cannot reproduce or metabolise without a host cell. Traditionally, they are classified according to the host they infect, be it an animal, a plant or prokaryotic bacteria.
“The jury’s still out on whether viruses are living or not, because they don’t fulfill all the requirements of a living organism, but they have a sort of key if you like, the way they outwit hosts, they’re clever players in the oceans of the world” says Weynburg.
“In terms of the marine environment, in one teaspoon of sea water you’re going to have as many as ten million viruses, but those viruses will again, not just be abundant, they’ll be hugely diverse, because they’re affecting so many different hosts.”
What Weynburg finds intriguing about viruses is they can be vectors for disease or work as part of an organisms’ immune system. A good example is when the activity of coral specific viral communities control the threat of bacterial pathogens, suggesting bacterial and viral communities have co-evolved with their coral hosts.
“I don’t think it’s a straight forward black and white situation where they’re all good, they’re all bad. It’s quite complicated and there’s a lot of dynamics and interactions going on” Weynburg says. “Viruses have to be very specific, very intimate with their host and therefore they’ve fine-tuned a strategy over millions of years.”
Innovative technology is assisting researchers like Weynburg to understand just who and what viruses are and their interaction with the environment.
“People are beginning to realise they’re playing a really crucial role and we have to start including them in future marine models and what’s actually happening in the oceans in terms of biological dynamics.”
Microscopic marine cyanobacteria drove the oxygenation of Earth 2.5 billion years ago and they continue to generate 50 percent of atmospheric oxygen and primary production in the oceans. Every week viruses spearhead a massive turnover of microbes in the world’s oceans by initiating a new generation.
“If you took all the viruses out of the ocean today, there would be no life in it tomorrow” Weynburg says.
“Everything would grind to a halt because viruses keep the system ticking over. They keep the whole energetics and dynamics in the oceans going.”
With climate change a reality, Weynburg says it is hard to predict how viruses will survive exposure to higher levels of UV and warmer ocean temperatures.
“We need more biological modelers to come in and really start plugging the data that we generate into models of what might happen in terms of climate change. We really don’t have the answer yet” Weynburg says.
In her research paper, Weynburg refers to how a virus’ selective behaviour during infection is geared toward protecting its survival in the environment, for example, holding onto heat shock proteins to survive heat stress.
“Virus’ only keep the bits of DNA that work for them” Weynburg says. “They don’t carry junk DNA like we do in our genomes. So, if they hold onto something like a heat-shock protein, it’s going to be playing an important role in their infection.”
Weynburg says viruses free up energy and nutrients for growing new cells by infecting and releasing the contents wrapped up in microscopic cells of marine microbes at the end of their lifetime.
These viruses also vicariously influence cloud formation by controlling blooms of cocolithophores in the sea and contribute to the recycling of iron crucial to biological processes in nutrient poor oceans.
“The blooms of the cocolithophores that you can see from space are huge and end up causing these cloud formations. The end of the blooms are actually only caused by two or three different strains of virus, which is quite fascinating” says Weynberg.
Management of climate is just one part of the viral power play. Since the mid 1970’s there has been an enormous leap in our understanding of marine virology. Weynburg’s research currently aims to mimic how viruses capture DNA segments and use this method to create whole genomes or existing genes.
“I’m sure down the line, viruses will have a myriad of roles that we can exploit if we think cleverly about it and we understand the system well enough” says Weynburg.
Questions about the ethics of applying synthetic biology tools are already being considered by researchers long before “the horse has bolted” says Weynburg. The synthesised genomes can be targeted to treat disease and aimed to be delivered by viral infection.
“Some people have already used virus captures to deliver proteins that will target cancer cells” she says. “If you think that you could use a virus to deliver something that would specifically attack a rogue cell, that is really exciting. We’re on that brink of discovery now. It’s real cutting edge technology.”
Report by Gabrielle Ahern
My interview with Dr Karen Weynburg will feature in an upcoming podcast episode of NOISEMAKERS published via SoundCloud and iTunes @saltywaveblue, so stay tuned.
The paper Marine prasinoviruses and their tiny plankton hosts: a review is published by the journal – Viruses.
Images of marine microbes along with many other ecology themed boards on my Pinterest site: @saltywave