In a new study, Efrem Lim and his colleagues examine an often-overlooked subset of the vaginal microbiome -- the viruses. Lim is a researcher with the ASU Biodesign Center for Fundamental and Applied Microbiomics, and an assistant professor at the ASU School of Life Sciences. The research demonstrates that crucial changes in the vast community of viruses or virome may enable persistent HPV infection and progression to cancer. The viral alterations appear to be associated with changes in bacterial composition and genital inflammation.

"Microbes maintain a delicate balance in our body to promote health," Lim says. "Viruses can tip the scale towards a worse health outcome."

The research appears in the current issue of the journalmSystems.

Cervical cancer is one of the most common cancers among women. In 2020, more than 600,000 cases and 340,000 deaths were reported worldwide. In addition to infection with the HPV virus, known risk factors for cervical cancer include immunodeficiency, smoking and oral contraceptive use.

Recent studies have explored the relationship of the vaginal microbiome to cervical cancer, though the viral component has often been neglected. Viruses interact with both human cells and the vast profusion of bacteria present in the genital tract. The new study uses next-generation gene sequencing to get a clearer read on the community of viruses present in vaginal microbiome samples from women in the Phoenix, Arizona metropolitan area.

The results highlight an association between genital inflammation and low abundance of the bacterial species Lactobacillus with reduction in virome diversity. Lactobacillus bacteria are known to be important mediators of genital health. Further, conditions conducive to persistent HPV infection were also associated with the abundance of a group of viruses that infect bacteria -- known as bacteriophages. The findings further emphasize the importance of studies of the virome and its complex interactions with other constituents of the human microbiome.