90 percent of skin-based viruses on healthy human skin represent viral 'dark matter', researchers.
Most DNA viruses on healthy human skin are viral 'dark matter' that have never been described before, according to researchers who used state-of-the-art techniques to survey the skin's virus population, or 'virome'.
The research also includes the development of a set of virome analysis tools that are now available to researchers for further investigations.
Researchers and the public are increasingly aware that microbes living on and inside us - our "microbiomes" - can be crucial in maintaining good health, or in causing disease. Skin-resident bacteria are no exception.
Ideally they help ward off harmful infections, and maintain proper skin immunity and wound-healing, but under certain circumstances they can do the opposite.
Previous mapping attempts used databases of known viral genes to recognise some of this viral genetic material amid all of the bacteria and human DNA. But such an approach tends to overlook the many viruses not already catalogued in databases.
Their analysis of samples from 16 healthy individuals revealed some results that were expected. The most abundant skin-cell infecting virus was Human Papilloma Virus (HPV), which causes common warts and has been linked to skin cancers.
However, most of the detected DNA from the virus-like particles virus-like particles (VLPs) did not match viral genes in existing databases.
"More than 90 percent was what we call viral dark matter - it had features of viral genetic material but no taxonomic classification," said senior author Elizabeth A Grice, an assistant professor of Dermatology at the University of Pennsylvania School of Medicine.
That came as a surprise, although of course it highlighted the importance of mapping this unexplored territory.
When Grice and colleagues sequenced skin bacterial DNA from the same 16 subjects, they found that it often contained tell-tale marks - called CRISPR spacers - of prior invasion by the same phage viruses.
The study was published in the journal mBio.
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