Characterization of the vaginal DNA virome in health and dysbiosis: an opening study in patients with non-female factor infertility

Background: Bacterial vaginosis (BV) is characterised by a reduction in Lactobacillus spp. abundance and increased abundance of facultative anaerobes, like Gardnerella vaginalis. BV aetiology is not fully understood, but bacteriophages could play a pivotal role causing perturbation of the vaginal bacterial community. Here we investigate the vaginal viral community, including bacteriophages, and its association to the bacterial community and BV-status. Methods: Vaginal samples from 48 patients undergoing IVF treatment for non-female factor infertility were subjected to metagenomic sequencing of purified virus-like particles. The vaginal viral community was characterized and correlated with BV-status, bacterial community structure and presence of key vaginal bacterial species. Results: The majority of identified vaginal viruses belonged to the class of double-stranded DNA bacteriophages, with eukaryotic viruses constituting 4% of total reads. Clear links between viral community composition and BV (q = 0.006, R = 0.26) as well as presence of L. crispatus (q = 0.001, R = 0.43), L. iners, Gardnerella vaginalis and Atopobium vaginae were found (q 0.15). Interestingly, also the eukaryotic viral community was correlated with BV-status (q = 0.018, R = 0.20). Conclusions: The vaginal virome is clearly linked with bacterial community structure and BV-status. Clinical Trials Registration: NCT02042352. Keywords: Vaginal microbiome; Vaginal virome; Bacteriophages; Bacterial vaginosis; Dysbiosis.