The original version of this story appears in Quanta Magazine.
Since viruses were discovered in the late 1800s, scientists have distinguished them from the rest of life. Viruses were much smaller than cells, and inside their protein coats they carried little more than genes. They couldn't grow, copy their own genes, or do much of anything. The researchers assumed that each virus was a solitary particle drifting alone across the globe, capable of replicating only if it hit the right cell that could absorb it.
It's this simplicity that has attracted many scientists to viruses, said Marco Vignuzzi, virologist at the Singapore Agency for Infectious Diseases Science, Research and Technology Laboratories. “We were trying to be reductionist.”
This reductionism has borne fruit. Virus studies played a crucial role in the birth of modern biology. Lacking the complexity of cells, they revealed fundamental rules about how genes work. But viral reductionism comes at a cost, Vignuzzi said: By assuming viruses are simple, you blind yourself to the possibility that they might be complicated in ways you don't yet know about.
For example, if we consider viruses as isolated sets of genes, it would be absurd to imagine them having a social life. But Vignuzzi and a new school of like-minded virologists don't think it's absurd at all. Over the past few decades, they have discovered strange features of viruses that make no sense if viruses are solitary particles. Instead, they discover a wonderfully complex social world of viruses. These sociovirologists, as the researchers are sometimes called, believe that viruses only make sense as members of a community.
Certainly, the social life of viruses is not entirely similar to that of other species. Viruses don't post selfies on social media, volunteer at food banks, or commit identity theft like humans do. They do not fight with allies to dominate a troop like baboons; they do not collect nectar to feed their queen like bees; they don't even congeal into sticky mats for their common defense as some bacteria do. However, sociovirologists believe that viruses cheat, cooperate and interact in other ways with their fellow viruses.
The field of sociovirology is still young and limited. The first conference dedicated to the social life of viruses took place in 2022, and the second will take place next June. In total, 50 people will be present. Yet sociovirologists say the implications of their new field could be profound. Illnesses like the flu make no sense if we consider viruses in isolation from each other. And if we can decipher the social lives of viruses, we may be able to harness it to fight the diseases that some of them create.
Under our noses
Some of the most important evidence for the social lives of viruses has been in plain sight for almost a century. After the discovery of the influenza virus in the early 1930s, scientists discovered how to accumulate the virus by injecting it into a chicken egg and allowing it to multiply inside. Researchers could then use the new viruses to infect laboratory animals for research or inject them into new eggs to continue developing new viruses.
In the late 1940s, Danish virologist Preben von Magnus was culturing viruses when he noticed something strange. Many viruses produced in one egg could not replicate when he injected them into another. By the third transmission cycle, only one virus in 10,000 could still replicate. But in the cycles that followed, defective viruses became rarer and those that were replicating bounced back. Von Magnus suspected that viruses that could not replicate had not finished developing and so he called them “incomplete.”