Immunization with Herpes Simplex Virus Nanoparticles Targeting Both Attachment and Fusion Protect Against Infection.

Area of Science:

• Virology
• Immunology
• Nanotechnology
• Vaccine Development

Background:

• Herpes simplex virus 2 (HSV-2) causes significant health issues, including genital ulcers, neonatal encephalitis, and increased HIV risk.
• Currently, no licensed vaccine is available to prevent HSV-2 infection and its associated complications.
• Developing an effective HSV-2 vaccine is a critical unmet medical need.

Purpose of the Study:

• To develop and evaluate a novel nanoparticle-based vaccine strategy targeting key HSV-2 proteins.
• To assess the immunogenicity and protective efficacy of the candidate vaccine in preclinical models.
• To investigate the mechanisms of protection induced by the vaccine, including antibody responses and fusion-blocking activity.

Main Methods:

• Engineered nanoparticles displaying HSV-2 attachment protein (gD) and fusion mediation complex (gH/gL).
• Immunized mice and non-human primates to assess antibody responses, including neutralization and fusion-blocking activity.
• Challenged vaccinated mice with HSV-2 to evaluate protection against disease, infection, and viral shedding.

Main Results:

• Nanoparticle immunization elicited high levels of neutralizing antibodies against HSV-2.
• Vaccination conferred robust protection in mice, preventing disease and significantly reducing infection and shedding.
• While gD induced high neutralization titers, gH/gL contributed substantially to protection via fusion-blocking responses, highlighting limitations of neutralization assays.

Conclusions:

• Targeting both HSV-2 attachment (gD) and fusion (gH/gL) proteins elicits complementary protective mechanisms.
• Fusion-blocking activity is a critical correlate of protection, underscoring the need to assess beyond standard neutralization assays.
• This nanoparticle-based vaccine strategy represents an innovative approach for developing a much-needed HSV-2 vaccine.