How many viruses on Earth?

How many different viruses are there on planet Earth? Twenty years ago Stephen Morse suggested that there were about one million viruses of vertebrates (he arrived at this calculation by assuming ~20 different viruses in each of the 50,000 vertebrates on the planet). The results of a new study suggest that at least 320,000 different viruses infect mammals. To estimate unknown viral diversity in mammals, 1,897 samples (urine, throat swabs, feces, roost urine) were collected from the Indian flying fox, Pteropus giganteus, and analyzed for viral sequences by consensus polymerase chain reaction. This bat species was selected for the study because it is known to harbor zoonotic pathogens such as Nipah virus. PCR assays were designed to detect viruses from nine viral families. A total of 985 viral sequences from members of 7 viral families were obtained. These included 11 paramyxoviruses (including Nipah virus and 10 new viruses), 14 adenoviruses (13 novel), 8 novel astroviruses, 4 distinct coronaviruses, 3 novel polyomaviruses, 2 bocaviruses, and many new herpesviruses. Statistical methods were then used to estimate that P. giganteus likely harbor 58 different viruses, of which 55 were identified in this study. If the 5,486 known mammalian species each harbor 58 viruses, there would be ~320,000 unknown viruses that infect mammals. This is likely to be un under-estimate as only 9 viral families were targeted by the study. In addition, the PCR approach only detects viruses similar t...
Source: virology blog - Category: Virology Authors: Tags: Basic virology Information bat discovery Indian flying fox PCR polymerase chain reaction Pteropus giganteus viral virus zoonosis Source Type: blogs