The Human Virome Program, supported by $171 million in federal funding, unites five universities in an effort to understand how viruses affect health. Scientists estimate that "tens of trillions of viruses live inside of us," with only a fraction identified. The five-year program will gather samples including "saliva, stool, blood, milk and other samples from thousands of volunteers" and inspect them with artificial intelligence systems.
Frederic Bushman, a microbiologist at the University of Pennsylvania and a program leader, stated, "I think it will swamp the data that we've had up until now." Early research, over a century ago, identified phages in stool samples, which could infect bacteria in the gut. Later discoveries revealed viruses infecting human cells without major symptoms, such as cytomegaloviruses, which can colonize almost every organ. Genetic sequencing in the early 2000s led to the discovery of more viruses in "saliva, blood and stool," allowing scientists to estimate viral numbers. "Each gram of stool," was found to contain billions of phages.
Evelien Adriaenssens, a phage biologist at the Quadram Institute in Norwich, England, anticipates discovering "tens of millions of species." In 1997, researchers in Japan found a new virus family, anelloviruses. A recent study revealed over 800 new species, bringing the total to over 6,800. Some studies question the definition of a virus, as scientists find "exquisitely tiny rings of free-floating RNA" in our bodies.
Dr. Pardis Sabeti, a computational biologist at Harvard T.H. Chan School of Public Health, notes that "totally new tools are going to have to come in." Her team is developing an artificial intelligence system for the Human Virome Program to identify subtle viral gene features. Research suggests phages and bacteria may have a partnership, not just a predator-prey relationship.
Colin Hill, a microbiologist at APC Microbiome Ireland, stated, "They're not in a fight to the death. They're in a partnership." Studies suggest phages distribute defensive genes to hosts, and cytomegaloviruses might defend against skin cancer.
Dr. Shadmehr Demehri, a Harvard cancer immunologist, found cytomegaloviruses activate in sun-damaged skin cells, attracting immune cells to attack damaged cells, preventing cancer. Dr. Demehri's studies also indicate human papillomaviruses can destroy tumor-prone skin cells. "It's a paradigm shift in how we think of viruses in general," said Dr. Demehri.