Modelling herpes simplex virus type 2 and Zika virus replication in mouse vaginal organoids and human vaginal spheroids.

Sexually transmitted viral infections disproportionately affect women and have adverse outcomes on maternal and fetal health. Since they are acquired through the vaginal tract, the vaginal epithelium is an important site to study host-viral interactions. An in vitro model of mouse vaginal epithelial organoids that can be infected by herpes simplex virus was recently established. Here, we used multiple vaginal organoid systems and studied their response to infection by herpes simplex virus type 2 (HSV-2) and Zika virus (ZIKV), both of which can be sexually transmitted and result in adverse effects on maternal and fetal health. We showed that mouse vaginal organoids support the replication of HSV-2 and ZIKV and respond to interferon treatment. We also established human vaginal spheroids from VK2/E6E7 cells that contain distinct apical and basal cell layers and are also susceptible to HSV-2 and ZIKV infection. Acyclovir treatment reduced HSV-2 replication in both mouse organoids and VK2 spheroids. However, ZIKV was restricted by remdesivir in VK2 spheroids but not in mouse organoids, indicating differences in antiviral activity depending on the organoid system. Finally, we established apical-out mouse vaginal organoids that were also susceptible to HSV-2 and ZIKV infection. Altogether, our results show that vaginal organoids and spheroids are useful in vitro models to study vaginal viral infections and effects of antiviral drugs.IMPORTANCEThe vaginal epithelium is the site of acquisition of sexually transmitted viral infections in women but has been historically understudied. 3D vaginal organoids that model the vaginal epithelium can be used to study virus-host interactions and provide novel insights. We demonstrated that vaginal organoids derived from mouse tissues could be infected with herpes simplex virus type 2 (HSV-2) and Zika virus (ZIKV), and these organoids are also capable of expressing immune genes. We then generated "flipped" mouse organoids that better represent the natural orientation of the vaginal epithelial lining. We also developed spheroids from human vaginal epithelial cells and showed that they can also be infected with HSV-2 and ZIKV. Finally, we showed that antiviral drugs reduced viral infection in these vaginal organoid and spheroid models. Our findings show that vaginal organoids and spheroids possess characteristics that make them useful models to study viral infections, as well as to test antiviral drugs.