EXECUTIVE SUMMARY

After promising research for a potential herpes vaccine stalled in 2018, scientists are finding new paths for investigation that may lead to a potential candidate. Recently published research by Yale University investigators may offer clues to an effective vaccine option.

  • More than one out of every six people ages 14-49 years has genital herpes. While treatment exists, there is no cure for the sexually transmitted infection.
  • Antiviral medications can help to prevent or shorten outbreaks while the person takes the medication. Daily suppressive therapy for herpes can lower the risk of transmission to partners.

More than one out of every six people ages 14-49 years has genital herpes, according to the CDC.1 While treatment exists to prevent or shorten outbreaks, there is no cure for the sexually transmitted infection (STI).

After promising research for a potential herpes vaccine stalled in 2018, scientists are investigating new paths. Recently published research by Yale University investigators may offer clues to an effective vaccine.2

Researchers conducted several experiments in mice vaccinated against the herpes simplex virus 2 (HSV-2). Results suggest that the HSV-2 antibody the body produces in response to vaccination is not present in the vaginal cavity where it is most needed to protect against infection. Also, researchers found that specialized immune cells, known as memory B cells, are physically drawn to the genital area, where they produce and insert the antibody in the inner vaginal tissue. Investigators concluded that having the HSV-2 antibody circulating in the blood alone is not enough to protect against genital herpes infection. A different strategy is needed to deliver the protective antibody in the future, researchers state.2

HSV-1 and HSV-2 are two of the most common herpes viruses. While both viruses appear similar on a clinical level and are sensitive to the same drug, acyclovir, they are genetically different. HSV-1 most commonly affects the mouth, while HSV-2 usually causes genital lesions. New research found evidence for ongoing recombination between HSV-1 and HSV-2 in humans today, as genital herpes due to HSV-1 is becoming increasingly common.3 Earlier research indicates an increasing proportion of anogenital herpetic infections attributed to HSV-1 infection, which is especially prominent among young women and men seeking sex with other men.4-6

“This could have important implications for HSV vaccine development because it means a live HSV-2 vaccine could recombine with circulating HSV-1 strains, thereby forming an infectious virus,” says Amanda Casto, MD, PhD, lead study author and a senior fellow in infectious diseases at the University of Washington School of Medicine.

Both HSV-1 and HSV-2 can cause incurable, lifelong infections. While both infections can be completely asymptomatic or lead to intermittent symptoms, not much progress has been made in preventing herpes.

“Herpes is one of the most stigmatized diseases out there, and yet it affects billions of people,” notes co-author Alex Greninger, MD, PhD, assistant professor of laboratory medicine at the University of Washington School of Medicine and assistant director of the UW Medicine Clinical Virology Laboratory. “We really need more work to combat this virus.”

Check Treatment Options

While there is no cure for genital herpes, antiviral medications can help to prevent or shorten outbreaks while the person takes the medication. Daily suppressive therapy for herpes can lower the risk of transmission to partners.

Randomized trials have indicated that three antiviral medications provide clinical benefit for genital herpes: acyclovir, valacyclovir, and famciclovir.7-10 While these medications may provide symptomatic relief from outbreaks, they do not cure HSV infection. Although the treatments can partially control the signs and symptoms of genital herpes when used to treat first clinical and recurrent episodes or when used as daily suppressive therapy, none can eradicate latent virus or affect the risk, frequency, or severity of recurrences after the drug is discontinued.

German drug maker AiCuris received fast track-status in August 2017 from the FDA to determine the safety and efficacy of oral pritelivir, the company’s lead candidate for the treatment of acyclovir-resistant mucocutaneous herpes simplex virus infections in immunocompromised adults. (Contraceptive Technology Update reported on pritelivir in its March 2017 article, “Task Force Recommends Against Genital Herpes Screening,” available at: http://bit.ly/2FSAU2U.)

REFERENCES

  1. Centers for Disease Control and Prevention. Genital herpes — CDC Fact sheet. Available at: https://bit.ly/2dxGM2l.
  2. Oh JE, Iijima N, Song E, et al. Migrant memory B cells secrete luminal antibody in the vagina. Nature 2019;doi:10.1038/s41586-019-1285-1.
  3. Casto AM, Roychoudhury P, Xie H, et al. Large, stable, contemporary interspecies recombination events in circulating human herpes simplex viruses. J Infect Dis 2019;doi:10.1093/infdis/jiz199.
  4. Ryder N, Jin F, McNulty AM, et al. Increasing role of herpes simplex virus type 1 in first-episode anogenital herpes in heterosexual women and younger men who have sex with men, 1992-2006. Sex Transm Infect 2009;85:416-419.
  5. Roberts CM, Pfister JR, Spear SJ. Increasing proportion of herpes simplex virus type 1 as a cause of genital herpes infection in college students. Sex Transm Dis 2003;30:797-800.
  6. Bernstein DI, Bellamy AR, Hook EW 3rd, et al. Epidemiology, clinical presentation, and antibody response to primary infection with herpes simplex virus type 1 and type 2 in young women. Clin Infect Dis 2013;56:344-351.
  7. Diaz-Mitoma F, Sibbald RG, Shafran SD, et al. Collaborative Famciclovir Genital Herpes Research Group. Oral famciclovir for the suppression of recurrent genital herpes: A randomized controlled trial. JAMA 1998;280:887-892.
  8. Mertz GJ, Loveless MO, Levin MJ, et al. Collaborative Famciclovir Genital Herpes Research Group. Oral famciclovir for suppression of recurrent genital herpes simplex virus infection in women: A multicenter, double-blind, placebo-controlled trial. Arch Intern Med 1997;157:343-349.
  9. Reitano M, Tyring S, Lang W, et al. International Valaciclovir HSV Study Group. Valaciclovir for the suppression of recurrent genital herpes simplex virus infection: A large-scale dose range-finding study. J Infect Dis 1998;178:603-610.
  10. Romanowski B, Marina RB, Roberts JN, et al. Patients’ preference of valacyclovir once-daily suppressive therapy vs. twice-daily episodic therapy for recurrent genital herpes: A randomized study. Sex Transm Dis 2003;30:226-231.