Like the Hindu god, Shiva, enigmatic viruses –not living, yet not dead–help create, protect and transform the universe. Viruses have had a huge impact on the history of all life on Earth. It was in the oceans that cover 2/3s of our planet, that life got its start. The oldest traces of life are fossils of marine microbes dating back almost 3.5 billion years.
“It was in the oceans,” point out Carl Zimmer in is classic 2011 summary, Planet of Viruses, “that multicellular organisms evolved; their oldest fossils date back to about 2 billion years ago. In fact, our own ancestors did not crawl onto land until about 400 million years ago.”
“The Ebola virus, once limited to small flare-ups in remote parts of Africa, exploded into a massive outbreak in cities like Freetown and Conakry, and, for the first time, spread to other continents,” writes Zimmer. New viruses, he observed, like MERS, leapt from animals to humans.
Fast forward to today, with our world locked down by the coronavirus pandemic believed to have been horizontally transferred by bats to humans, Mother Nature is in her nuanced way of educating us. Following a century of scientific and technological advances that triggered unprecedented economic growth, our civilization perceived its superiority over nature as undisputed, writes Harvard astrophysicist Avi Loeb.
“Like corrections to irrationally exuberant stock markets, however, COVID-19 is a correction to human hubris,” he concludes.” Nature is teaching all humans, rich and poor, to be humble. Although we thought we can manipulate nature at our will, here comes a primitive coronavirus with negligible information content relative to our brain, threatening to kill us and wreck our economy, causing as much damage from the side effects triggered by our societal reaction to it as from its direct medical impact.”
We are all painfully aware that we are living in what Zimmer coined as an “unimaginably vast” virosphere where virologists have officially named 6,828 species. Yet scientists have discovered hundreds of thousands of un-named new species, with perhaps even trillions of species waiting to be found.
“Suffice to say that we have only sampled a minuscule fraction of the virosphere,” observes Edward Holmes of the University of Sydney.
“Right now, we are in the exponential phase,” said Dr. Jens H. Kuhn, the lead virologist at the Integrated Research Facility at Fort Detrick in Maryland. “If someone gives me a million dollars and I go out and sample sea cucumbers, I will present you with 10,000 new viruses.”
Matthew Sullivan, a virologist and head of the Sullivan Lab at The Ohio State University –that investigates the roles of marine viruses in regulating microbial communities through mortality, horizontal gene transfer, and metabolic reprogramming– has used this method to search for viruses that infect life in the ocean by analyzing genetic material in seawater collected on scientific voyages around the world. Some genes belonged to species already known to science. But many were new. In 2016, Sullivan and his colleagues reported over 15,000 viruses, each representing a new species.
In 1986 a graduate student at the State University of New York at Stony Brook named Lita Proctor traveled to the Caribbean and the Sargasso Sea, sampling seawater along the way in what may have been the first ever exploration of the number of viruses living in Earth’ s oceans. What Proctor discovered was astounding: every liter of seawater contained up to one hundred billion viruses. when other scientists followed up on her work and carried out their own surveys, they estimated that there are somewhere in the neighborhood of 10,000,000,000,000,000,000,000,000,000,000 per liter –If you lined up all the viruses in the ocean, Zimmer summarized they would stretch out from Earth for 42 million light years.
In short, marine viruses have a massive influence on the planet, influencing the ecology of the world’s oceans. the Earth’s global climate. They have been playing a crucial part in the evolution of life for billions of years. They are, observes Zimmer, biology’s living matrix, being powerful because they are so infectious.
“They invade a new microbe host ten trillion times a second, and they kill between 15 and 40 percent of all bacteria in the world’s oceans every single day,” according to Zimmer “By killing these hosts, they create swarms of new viruses. Every liter of seawater generates up to 100 billion new viruses every day—viruses that can promptly infect new hosts. Their lethal efficiency keeps their hosts in check, and we humans often benefit from their deadliness. Cholera, for example, is caused by blooms of waterborne bacteria called Vibrio. But Vibrio are host to a number of phages. When the population of Vibrio explodes and causes a cholera epidemic, the phages multiply. The virus population rises so quickly that it kills Vibrio faster than the microbes can reproduce. The bacterial boom subsides, and the cholera epidemic fades away.”
As the novel corona virus illustrates, doctors are grappling with a growing number of bacteria that have evolved resistance to most of the antibiotics available today. This week, Scientists say the now-dominant strain of the coronavirus appears to be more contagious than original. An early draft of a study from researchers at Los Alamos National Laboratory — which has not been published or peer-reviewed yet — suggests that the coronavirus mutated over the past few months. They concluded that the strain of the virus that has afflicted most people in the US is the newer version.
The trillions of marine viruses that inhabit the world’s oceans, says Ohio State’s Matt Sullivan, could be mobilized in the fight against climate change. New studies suggest that manipulating the viruses that infect most of the bacteria in the oceans enables the microbes to absorb more carbon dioxide from the atmosphere, which could be employed to tackle global warming.
Viruses, known as phages, influence many aspects of their bacterial hosts’ behavior, including the amount of carbon dioxide they absorb. This affects climate because bacteria in the oceans are an important “carbon sink”, removing warming gas from the atmosphere.
“We have been asking which organisms drive carbon export into the oceans,” said Sullivan. “It turns out viruses best predict carbon absorption into the deep sea. We have been asking which organisms drive carbon export into the oceans. It turns out viruses best predict carbon absorption into the deep sea.”
Before the Ohio team began investigating the effect of phage infection on marine microbes, it was assumed that viruses reduced the uptake of carbon dioxide in bacteria. The latest research shows that, on the contrary, infected bacteria absorb more carbon, which then sinks to the ocean floor.
The earth has already warmed about 1C since pre-industrial times, and almost all the countries in the world have pledged to limit global warming to less than 2C — a level that would require drastically cutting back on carbon dioxide emissions. If the oceans that cover 70 per cent of the earth’s surface can be harnessed to suck carbon dioxide out of the atmosphere it could help to slow down the warming process.
“There is already talk of developing bioreactors to grow suitable viruses and seed the oceans with them to increase carbon uptake,” Sullivan told the annual meeting of the American Association for the Advancement of Science in Washington. “People are thinking about the engineering that would be needed to do this at scale. But first we need to make sure we understand the cell-virus interactions.”
Image credit top of page: With thanks to artist Michel Rento, Art Station.