Cultivated Human Vaginal Microbiome Communities Impact Zika and Herpes Simplex Virus Replication in ex vivo Vaginal Mucosal Cultures

Abstract

The human vaginal microbiome (VMB) is a complex bacterial community that interacts closely with vaginal epithelial cells (VECs) impacting the mucosal phenotype and its responses to pathogenic insults. The VMB and VEC relationship includes nutrient exchange and regulation of signaling molecules that controls numerous host functions and defends against invading pathogens. To better understand infection and replication of sexually transmitted viral pathogens in the human vaginal mucosa we used our ex vivo VEC multilayer culture system. We tested the hypothesis that selected VMB communities could be identified that alter the replication of sexually transmitted viruses consistent with reported clinical associations. Sterile VEC multilayer cultures or those colonized with VMB dominated by specific Lactobacillus spp., or VMB lacking lactobacilli, were infected with Zika virus, (ZIKV) a single stranded RNA virus, or Herpes Simplex Virus type 2 (HSV-2), a double stranded DNA virus. The virus was added to the apical surface of the cultured VEC multilayer to model transmission during vaginal intercourse. Viral replication was measured 48 h later by qPCR. The results indicated that VEC cultures colonized by VMB containing Staphylococcus spp., previously reported as inflammatory, significantly reduced the quantity of viral genomes produced by ZIKV. HSV-2 titers were decreased by nearly every VMB tested relative to the sterile control, although Lactobacillus spp.-dominated VMBs caused the greatest reduction in HSV-2 titer consistent with clinical observations. To explore the mechanism for reduced ZIKV titers, we investigated inflammation created by ZIKV infection, VMB colonization or pre-exposure to selected TLR agonists. Finally, expression levels of human beta defensins 1–3 were quantified in cultures infected by ZIKV and those colonized by VMBs that impacted ZIKV titers. Human beta defensins 1–3 produced by the VEC showed no association with ZIKV titers. The data presented expands the utility of this ex vivo model system providing controlled and reproducible methods to study the VMB impact on STIs and indicated an association between viral replication and specific bacterial species within the VMB.

Novel Ex Vivo Model to Examine the Mechanism and Relationship of Esophageal Microbiota and Disease

“…Primary and immortalized cell lines have been created previously by our lab using nasal and vaginal mucosa [ 27 , 28 , 29 ]. To create esophageal cell lines, immortalized cell lines were derived from human esophageal mucosal biopsies transformed with human papilloma virus E6E7.…”

Is the ZIKV Congenital Syndrome and Microcephaly Due to Syndemism with Latent Virus Coinfection?

“…Cases of ZIKV/HSV-2 coinfections have already been described in pregnancy in several prospective studies [ 52 ]. In addition, one comparative study showed that HSV-2 infection induces cytotoxic and inflammatory effects in the sterile vaginal system, while ZIKV infection alone does not result in obvious epithelial destruction [ 152 ].…”

“…HSV-2 induces immunomodulation and proinflammatory cytokine production (including interleukins IL-8 and IL1β) making it an ideal antagonistic or synergetic partner in enhancing ZIKV pathogenicity in pregnancy ( Figure 4 : Pathogenesis changes) [ 152 ]. ZIKV RNA accumulation in the placenta of pregnant C57BL/6 mice exposed to HSV-2 at day E8.5 (equivalent to the first trimester in humans) and then infected with ZIKV at day E11.5 was significantly higher compared to pregnant mice monoinfected with ZIKV alone (Replication promotion).…”

Histologic features, pathogenesis, and long-term effects of viral oophoritis

“…In humans, ZIKV RNA was identified in the oocytes, but not in follicular fluid or cumulus cells, of a woman infected with ZIKV undergoing in vitro fertilization (IVF) (42). In addition, ZIKV has been shown to infect cells of other female reproductive organs, including cultured endometrial stromal cells and vaginal epithelial cells collected from humans (43,44). While Zika infection appeared cytotoxic in endometrial cells, it did not induce significant cytotoxicity or inflammation in the vaginal epithelial cells (43,44).…”