If antibiotics, benzoyl peroxide or old-fashioned soap aren’t any help in conquering your pimples, scientists think they could add another acne remedy to the medicine cabinet: viruses.

In a paper published on Tuesday in the journal mBio, researchers from the University of Pittsburgh and UCLA examined the genomes of 11 phage viruses that prey on the acne-causing bacterium Propionibacterium acnes, which causes skin flareups when it multiplies rapidly deep within the pores and follicles of the skin.

The scientists found that the 11 phages – isolated from both laboratory strains and the noses of human volunteers – were extremely genetically similar. 85% of the DNA was shared amongst the viral genomes, which is unheard of, the authors say. Bacteriophages usually diverge quite quickly in order to surmount new antiviral defenses that evolve in bacteria.

According to the authors, the similarity amongst the various phages means that it’s less likely that P. acnes will develop resistance to a virus-based treatment.

"There are two fairly obvious potential directions that could exploit this kind of research," author and University of Pittsburgh researcher Graham Hatfull of the University of Pittsburgh said in a statement Tuesday. "The first is the possibility of using the phages directly as a therapy for acne. The second is the opportunity to use phage-derived components for their activities."

One explanation for the lack of genetic diversity among the P. acnes-targeting viruses may be due to the fact that the acne-causing bacterium is adapted to a very specific niche. P. acnes lives solely in the deep in the follicles and pores of human skin, where it feeds on sebum and bits of cellular trash. In the follicle, P. acnes doesn’t have much competition, unlike bacteria in the gut, which have to deal with a virtual rainforest of diverse fellow microbes.

“The unexpected but striking limited diversity of these phages… likely reflects the coevolution of virus and bacteria in a distinct and restricted microenvironment,” the authors wrote in their paper.

Hatfull and his colleagues also found that the 11 viruses they studied carry a gene for the enzyme endolysin, which can degrade bacterial cell walls. If using the viruses themselves to fight acne proves unwieldy, the thinking goes, perhaps isolating the enzyme from the viruses could be the basis for a topical treatment.

"This work has given us very useful information about the diversity of that set of enzymes and helps pave the way for thinking about potential applications," Hatfull said.

SOURCE: Marinelli et al. “Propionibacterium acnes Bacteriophages Display Limited Genetic Diversity and Broad Killing Activity against Bacterial Skin Isolates.” mBio 5: e00279-12, 25 September 2012.

Medicine