Most of our normal skin-resident viruses reside in our skin bacteria, but may affect health via their influence on the microbiome.
More than 90 percent of skin-based viruses represent “dark matter,” meaning it has viral genetic features but no taxonomic classification, according to a new study by University of Pennsylvania (Penn) scientists, published October 2015 in the open-access journal mBio.
“Skin viral communities and their relationships with their hosts remain poorly understood despite their potential to modulate states of cutaneous health and disease,” according to the study’s abstract.
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Researchers from Penn’s Perelman School of Medicine collected samples from 16 subjects, at eight body sites, during a period of a month. In their survey of the skin's virus population, or virome, they found human papilloma virus to be the most abundant skin-cell infecting virus, but most of the DNA they detected from virus-like particles did not match documented viral genomes.
The study’s findings clearly link the skin virome to the skin microbiome, according to a Penn press release.
Most of the viral DNA detected seemed to belong to phage viruses, which infect and often live for long periods within bacteria. The researchers found that the microenvironment and natural skin occlusion were strongly associated with skin virome community composition, according to the study.
“Although the results suggest that most of our normal skin-resident viruses are in fact resident in our skin bacteria, such viruses can still affect our health via their influence on the microbiome. The Penn researchers found evidence in the phage DNA of genes that could make host bacteria more resistant to antibiotics, for example, or more likely to cause a harmful infection,” according to the release.
Skin virome varies depending on where it is on the body. Senior author Elizabeth A. Grice, Ph.D., an assistant professor of Dermatology at Penn Medicine, and colleagues analyzed subjects’ palms, foreheads, armpits, navels and elsewhere, but found virome was most diverse in the crook of the arm.
The research sets a foundation for future investigations of the normal, healthy skin virome and how it changes with disease. Scientists who want to pursue such studies can freely use a set of virome analysis tools, developed by the Penn researchers, which are available in the paper’s supplemental information.
"There has been a real need for a better understanding of these viruses, given their potential effects on our skin cells as well as on our resident bacteria," said senior author Elizabeth A. Grice, PhD, an assistant professor of Dermatology at Penn Medicine. "Until now, relatively little work has been done in this area, in part because of the technical challenges involved."
Reference: Hannigan GD, Meisel JS, Tyldsley AS, Zheng Q, Hodkinson BP, SanMiguel AJ, Minot S, Bushman FD, Grice EA. The Human Skin Double-Stranded DNA Virome: Topographical and Temporal Diversity, Genetic Enrichment, and Dynamic Associations with the Host Microbiome. MBio. 2015 Oct 20;6(5). http://www.ncbi.nlm.nih.gov/pubmed/26489866