Viruses, the most abundant biological entities on earth, are a scourge on humanity, causing both chronic infections and global pandemics that can kill millions. Yet, the true extent of viruses that infect humans remains completely unknown. Some newly discovered viruses are recognized because of the sudden appearance of a new disease, such as SARS in 2003, or even HIV/AIDS in the early 1980s. New techniques, however, now enable scientists to identify viruses by directly studying RNA or DNA sequences in genetic material associated with humans, enabling detection of whole populations of viruses—termed the virome—including those that may not cause acutely recognizable disease. However, identifying novel types of viruses is difficult as their genetic sequences may have little in common with already known viral genomes that are available in reference databases.
* This article was originally published here