Herpesviruses exemplified by herpes simplex virus-1 (HSV-1) attach to cell surface heparan sulfate (HS) for entry into host cells. However, during a productive infection the HS moieties on parent cells can trap newly exiting viral progenies and inhibit their release. Here, we demonstrate that a HS-degrading enzyme of the host, heparanase (HPSE), is upregulated through NF-kB and translocated to the cell surface upon HSV-1 infection for the removal of HS to facilitate viral release. We also find a significant increase in HPSE release in vivo during infection of murine corneas and that knockdown of HPSE in vivo inhibits virus shedding. Overall, we propose that HPSE acts as a molecular switch for turning a virus-permissive “attachment mode” of host cells to a virus-deterring “detachment mode”. Since many human viruses use HS as an attachment receptor, the HPSE-HS interplay may delineate a common mechanism for virus release.

The attachment of Herpes simplex virus type-2 (HSV-2) to a target cell requires ionic interactions between negatively charged cell surface co-receptor heparan sulfate (HS) and positively charged residues on viral envelop glycoproteins, gB and gC. Effective blocking of this first step of HSV-2 pathogenesis demonstrates significant prophylactic effects against the viral disease; any in vitro therapeutic effects of blocking this interaction, however, are not clear. Here, we provide new evidence that zinc oxide tetrapod micro-nanostructures synthesized by flame transport approach significantly block HSV-2 entry into target cells and, in addition, demonstrate the potential to stop the spread of the virus among already infected cells. The zinc oxide tetrapods (ZnOTs) also exhibit the ability to neutralize HSV-2 virions. Natural target cells such as human vaginal epithelial and HeLa cells showed highly reduced infectivity when infected with HSV-2 virions that were pre-incubated with the ZnOTs. The mechanism behind the ability of ZnOTs to prevent, neutralize or reduce HSV-2 infection relies on their ability to bind the HSV-2 virions. We used fluorescently labeled ZnOTs and GFP-expressing HSV-2 virions to demonstrate the binding of the ZnOTs with HSV-2. We also show that the binding and hence, the anti-viral effects of ZnOTs can be enhanced by illuminating the ZnOTs with UV light. Our results provide new insights into the anti-HSV-2 effects of ZnOT and rationalize their development as a HSV-2 trapping agent for the prevention and/or treatment of infection. The observed results also demonstrate that blocking HSV-2 attachment can have prophylactic as well as therapeutic applications.

Virtually all efforts to generate an effective protection against the life-long, recurrent genital infections caused by Herpes simplex virus-2 (HSV-2) have failed. Apart from sexual transmission, the virus can also be transmitted from mothers to neonates, and is a key facilitator of HIV co-acquisition. Here, we uncover a nanoimmunotherapy using specially designed Zinc Oxide Tetrapod Nanoparticles (ZOTEN) with engineered oxygen vacancies. We demonstrate that ZOTEN, when used intravaginally as a microbicide, is an effective suppressor of HSV-2 genital infection in female BALB/c mice. The strong HSV-2 trapping ability of ZOTEN significantly reduced the clinical signs of vaginal infection and effectively decreased animal mortality. In parallel, ZOTEN promoted the presentation of bound HSV-2 virions to mucosal antigen presenting cells, enhancing T cell- mediated and antibody-mediated responses to the infection, and thereby, suppressing a re-infection. We also found that ZOTEN exhibits strong adjuvant-like properties, which is highly comparable to alum, a commonly used adjuvant. Overall, our study provides very first evidence for the protective efficacy of an intravaginal microbicide/vaccine or microbivac platform against primary and secondary female genital herpes infections.