Study may aid herpes cure

In a world where where the potential to acquire sexually transmitted diseases has grown, a discovery by Yale School of Medicine researchers may be the first step in a cure for one of the most common: genital herpes.

Immunobiology professor Akiko Iwasaki published a study this month discussing the response of the body’s immune system to invasion by the herpes simplex virus, or HSV. The study isolated one type of herpes virus — HSV-1 — and tested the responses of two key immune receptors known as TLR2 and TLR9. The research project found that only a very small percentage of the herpes patients studied carried a form of HSV-1 that instigates an immune response in TLR2, while all forms of HSV-1 isolated in patients trigger TLR9.

“What was interesting was … that for the HSV-1 variant that triggered TLR2, full activation of dendritic cells also required TLR9, suggesting that there is a sequential activation of these two receptors within the same dendritic cell,” Iwasaki said in a statement.

Dendritic cells are immune cells such as those present in the skin or the lining of the lungs that come in contact with external environments and work to shape the immune response when activated.

Iwasaki also said that the research results indicate the possibility for a means of HSV treatment.

“This study has implications on the possible treatment options for herpes encephalitis by controlling inflammatory pathways induced through these Toll-like receptors,” she said.

Herpes, which is currently incurable, is a significant presence on college campuses, Director of Yale University Health Services Paul Genecin said in an e-mail. But its tendency to remain latent means that its prevalence is often underestimated in clinical studies, he said.

“HSV continues to be a prevalent disease,” he said. “In college health, we are seeing an increase in concern about HSV — and this leads to more serologic testing. That, of course, leads to more cases identified. We do not track cases year to year, but prevalence certainly isn’t decreasing.”

Because a cure for HSV does not yet exist, Yale’s Peer Health Educators focus on prevention when talking to students, Axel Schmidt ’09 said in an e-mail.

Members of Peer Health teach safe sex procedures and advocate testing if a student believes him or herself to be at risk of having contracted a sexually transmitted infection, he said.

“We spend a good deal of time talking about [STIs],” Schmidt said. “STI testing and treatment is available to students at YUHS. Because STIs can have serious long-term consequences, getting tested [if you are at risk] is the responsible thing to do.”

While the study raises interesting questions about the activation of TLR2 or lack thereof, Iwasaki said, the test sample size was too small to draw any statistical conclusions. Iwasaki also said there were no distinguishing symptoms in patients with the rare TLR2-responsive form of the virus as opposed to those with the more common form.

Genecin also said the process of developing pharmaceuticals is a long and arduous one and can require decades. Still, he said, such research has an enormous impact on medical practice.

“This is an extremely important field of research because HSV and related viruses are [significant] causes of morbidity and mortality,” he said.

Schmidt said he hopes that one day a preventative vaccination can be developed with the help of research projects such as this one.

“The biggest impact will occur if a vaccine can be produced against herpes,” he said. “Just recently, a safe and effective HPV vaccine was released, and that is a huge step forward in battle against viral STIs.”

Iwasaki’s co-authors included postdoctoral fellow Ayuko Sato and research associate Melissa Linehan.

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