Genital herpes is a sexually transmitted disease (STD). This disease causes herpetic sores, which are painful blisters (fluid-filled bumps) that can break open and ooze fluid. Around 417 million people globally have this STD.
Herpes simplex virus (HSV) type 2, which causes genital herpes, is prevalent. Almost all infected people develop recurrences, either recurrent lesions or even more recurrent shedding in the absence of lesions. There’s no cure, and efforts to develop a vaccine have had limited success.
In a recent study, Yale scientists have shown that a combination of a vaccine and a medicated cream is a promising strategy to diminish the recurrence of genital herpes drastically. Scientists tested a new vaccine strategy called prime and pull in guinea pigs infected with genital herpes.
The prime and pull strategy relies on two steps: (1) conventional parenteral vaccination to elicit systemic T-cell responses (prime), followed by 2) recruitment of activated T cells via topical administration of a T cell attractant (pull), where such T cells establish long-term protective immunity.
The ‘prime’ involves a vaccine that generates a response to the virus from T cells, highly specialized immune cells. The ‘pull’ consists of a cream containing imiquimod, a medication commonly used to treat genital warts.
Applied to the affected area, the cream attacks key immune cells at the site of infection, where they can block the virus from spreading and causing herpes lesions. After three rounds of treatment to the animals, scientists noted that the strategy worked rapidly, beginning with the first round.
Co-corresponding author Akiko Iwasaki, the Waldemar Von Zedtwitz Professor of Immunobiology at Yale School of Medicine, said, “The study showed that the effect of the combination therapy was far greater than either the vaccine or cream alone. It’s the first time that a study has shown that prime-and-pull strategy can block existing recurrent disease.”
David Bernstein, professor of pediatrics and former director of the Division of Infectious Diseases at Cincinnati Children’s Hospital, said, “Development of a therapeutic HSV vaccine is a high priority. Our exciting results have encouraged us and, hopefully, others to pursue this strategy with more vaccines.”
Iwasaki said, “This strategy if developed into a therapy for humans, could be a game-changer for individuals with recurrent infections or resistance to standard antiviral treatment. Active herpes infection causes painful lesions that are physically and emotionally harmful to affected people.”
The study, conducted in collaboration between scientists at the University of Pennsylvania and University of Cincinnati Children’s Hospital Medical Center, is published in the journal npj Vaccines.