Researchers at Yale School of Medicine announced on June 22 a significant advance in the development of a genital herpes vaccine that, in preclinical models, prevented infection. The new approach, described in a study published June 19 in Science Immunology, uses a two-part vaccination strategy combining an intramuscular injection with localized delivery of nanoparticles to the vagina.
The method begins with a typical intramuscular shot to "prime" the immune system. This is followed by introducing nanoparticles—called BEACON (Bioactive Enhanced Adjuvant Chemokine Oligonucleotide Nanoparticles)—to the vaginal area where herpes infection typically occurs in women. The combination aims to direct immune activity precisely to where it is needed most.
Previous efforts found that standard intramuscular vaccines did not create strong immune cell populations or antibodies at the vaginal lining, limiting their effectiveness against herpes virus introduction. To address this challenge, researchers first tried using chemokines to attract immune cells locally but found only partial protection since necessary B cells were not engaged. Another attempt used immunostimulating DNA molecules but resulted in inflammation.
Sachin Bhagchandani, lead author and postdoctoral researcher in Iwasaki's lab, said, "We had these two really promising strategies in the lab, but each had some shortcoming. So we set out to formulate a particle that could overcome those shortcomings." The resulting BEACON nanoparticle links immunostimulating DNA with chemokines for stability and targeted effect.
In tests with female mice primed by an intramuscular vaccine and then treated with BEACON plus viral antigen applied intravaginally, strong local immune responses were established that lasted at least six months. Mice receiving both treatments showed 80% resistance to infection over six months compared to just 40% for those given only the injection. Iwasaki said, "This formulation is quite remarkable in that way." Bhagchandani added, "That showed us that this approach could be profoundly impactful, establishing local immune responses for a significantly long period of time."
The research team is now exploring whether this method can also treat existing infections and considering how it might be adapted for human use—including collaboration on creating translatable formulations such as vaginal suppositories or nasal applications suitable for men. Looking ahead toward human clinical trials, Iwasaki said, "A lot of the suffering patients go through is not just physical; it's mental and societal... We hope that this kind of strategy will prevent diseases that affect people in a profound way."
