While everybody has heard of the cold virus and many others that infect people, there are a number of viruses lurking out there in other animals. Other animals, Megan Gannon at LiveScience notes, have been the source of viruses like HIV, SARS, and West Nile that are fairly new to infecting people.
Researchers from Columbia University, the EcoHealth Alliance, and elsewhere report in mBio this week that there are at least 320,000 mammalian viruses waiting to be uncovered.
To arrive at this estimate, the researchers repeatedly sampled the Indian Flying Fox, Pteropus giganteus, a known host of emerging viruses. Using degenerate viral family-level PCR primers, the investigators uncovered and analyzed the occurrence patterns of the viruses, and then, using a statistical calculation, they determined that the total viral richness of those nine viral families was 58 viruses. From that, they extrapolated that there are 320,000 viruses from those nine families waiting to be uncovered in other mammals, assuming that other mammalian species harbor similar numbers of viruses as the flying bat.
"What we currently know about viruses is very much biased towards those that have already spilled over into humans or animals and emerged as diseases," Columbia's Simon Anthony, said in a statement, adding that "the pool of all viruses in wildlife, including many potential threats to humans, is actually much deeper."