Vaccine has potential to prevent genital herpes

The conventional thinking is that an effective HSV-2 vaccine must stimulate the body to produce neutralizing antibodies, particularly against the viral protein glycoprotein D (gD-2) through which HSV-2 accesses human cells. Researchers in the past have focused on “sub-unit” herpes vaccines that rely primarily on gD-2 as the antigen to stimulate the body’s antibody response. None of these, however, has prevented HSV-2 infection in humans.

Using a non-traditional approach, a research team at the Albert Einstein College of Medicine, Bronx, N.Y research team-headed by Betsy Herold, M.D., and William Jacobs Jr., Ph.D.-developed a vaccine that prevented active and latent infections caused by herpes simplex virus type 2 (HSV-2) from occurring in mice and published their findings.¹

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According to Dr. Jacobs, professor and Leo and Julia Forchheimer chair in microbiology and immunology at Einstein, the team took an approach that runs counter to what most scientists take. “We took a completely different approach and deleted glycoprotein D from the virus,” Dr. Herold, vice chair for research at Einstein, told Dermatology Times. “The deleted strain, which is markedly attenuated and cannot spread, is completely safe and provided 100% protection against both HSV-1 and HSV-2, and prevented the establishment of latency in different mouse models, including a model of skin infection.”

When the vaccine, called delta-gD-2, was given to mice, it provided complete protection against subsequent infection with normal HSV-2. No virus was detected in vaginal or skin tissue of vaccinated mice or in neural tissue, where HSV-2 often lays latent. When unvaccinated mice were challenged with HSV-2, all showed evidence of the virus in the three tissue sites, and all succumbed to the disease. Initial tests suggest that the vaccine is also effective against HSV-1, though further evaluation is needed to confirm this.

NEXT: Safety of vaccine

The new vaccine also appears to be safe. The researchers calculated the number of viruses needed to kill mice, then administered 1,000 times that number of delta-g D-2 viruses to mice that lacked immune systems. The result: The mice survived and didn’t develop herpes.

“For the first time in history, we have successfully developed a vaccine that prevents HSV-1 and HSV-2, using an approach that experts thought was doomed to fail,” Dr. Jacobs says. “If this vaccine protects humans as it does mice, herpes could be eradicated.”

The Einstein team plans to begin clinical trials on humans within a few years.

“We hope that this vaccine candidate, which elicits a different type of immune response than prior vaccines, will prove equally protective in clinical studies,” Dr. Herold tells Dermatology Times. “We are planning to conduct the pre-clinical studies required by the Food and Drug Administration to allow us to move this vaccine into a Phase I clinical trial.”

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NEXT: References

Disclosures:

The Albert Einstein College of Medicine has filed patent applications related to this research and is seeking licensing partners able to further develop and commercialize this technology.

References:

1.   Petro C, González PA, Cheshenko N, et al. Herpes simplex type 2 virus deleted in glycoprotein D protects against vaginal, skin and neural disease. Elife. 2015;4