Elucidating the Interactions between Heparanase and Heparanase 2 During a Herpes Simplex 2 Infection

Herpes simplex virus 2 (HSV-2) can productively infect many different cell types of human and nonhuman origin. Nucleoside analogs such as acyclovir (ACV) are currently prescribed clinically to curb this infection. Here we demonstrate interconnected roles for host enzymes, heparanase (HPSE), heparanase 2 (HPSE 2) and cathepsin L (Cath L), in HSV-2 release and inhibition in cells. In vaginal epithelial cells, HSV-2 causes heparan sulfate shedding and upregulation in HPSE, HPSE 2 and, Cath L protein levels during the productive phase of infection. Furthermore, inhibition of HPSE dramatically reduces HSV-2 release from vaginal epithelial cells, while HPSE 2 inhibition also show markedly less infection. Overexpression of HPSE leads to an increase in viral progeny, interestingly overexpression of HPSE 2 leads to less virus production. This work proposes that the HPSE increase after infection is mediated by an increased NF-_B nuclear localization and a resultant activation of HPSE transcription. Together these mechanisms contribute to the removal of heparan sulfate from the cell surface and thus facilitate virus release from cells. For HPSE 2 it’s proposed that the increase after infection is a response to the clearing of HS that can lead to some inhibition of infection, though more work is needed on this. Finally, also studied was a small molecule inhibitor, BX795, as a new and alternative solution to reduce HSV burden in humans. This work reported evidence for strong antiviral efficacy of BX795 on HSV-2 infection in vaginal epithelial cells in vitro at 10 µM and in vivo at 50 µM. Additionally, through biochemical assays in vitro and histopathology in vivo, it was showed that the tolerability of BX795 in vaginal epithelial cells at concentrations as high as 80 µM. Finally, using a murine model of vaginal infection, it was shown that topical therapy using 50 µM BX795 is well tolerated and efficacious in controlling HSV-2 replication.