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Genital HSV Vaccine Provides Powerful Protection in Preclinical Trials

JAN 27, 2017 | KRISTI ROSA

To test the new vaccine, the researchers teamed up with the Tulane National Primate Center in Louisiana to see how the vaccine would fare in macaque monkeys, because their immune system is similar to that of a human’s. Dr. Friedman and his team administered the trivalent vaccine “three times at monthly intervals” and found that it induced a strong immune response against all three of the glycoproteins in both blood and vaginal secretions. When analyzed in a lab dish, the researchers found that the antibodies were able to neutralize the virus, preventing its spread throughout the cells. In addition, the researchers noted a “sharp rise in CD4 T-cells, whose job it is to mobilize the antibody response and other immune elements against viral infections.” Furthermore, they found that the antibodies were able to neutralize four HSV2 isolates that are from sub-Saharan Africa.

The study authors noted that although it is not typical for macaques to develop genital lesions as a result of HSV2 infection, some of the monkeys that did not receive the vaccine did exhibit minor vaginal inflammation. In contrast, the macaques that were vaccinated did not present with any vaginal inflammation.

Taking it a step further, the researchers decided to test the vaccine on guinea pigs, which, according to the press release, are prone to develop a more severe bout of genital lesions when infected with HSV2. Their findings? The vaccine prevented genital lesions in the guinea pigs. Although they noted that the vaginal swabs did present with a “small amount of viral DNA,” they found that “only a tiny fraction” of it would be able to replicate, according to the press release.

The study’s lead author, Sita Awasthi, PhD, research associate professor of Infectious Diseases at Penn said in the press release, “We are pleased to have demonstrated such a potent and durable immune response to the vaccine. If found effective in clinical trials, the vaccine will have a huge impact on reducing the overall prevalence of genital herpes infections and could reduce new HIV infections as well, especially in high-burden regions of sub-Saharan Africa."

Dr. Friedman added, “If the vaccine behaves like this in people, it would limit lesions to appearing only about one day in 100, and the virus would be potentially contagious only about two in every 1,000 days.” This means that, “in principle,” it would potentially prevent HSV2 from spreading throughout the population. He told Contagion®, "We won't know how good it will be in humans. We hope to test our trivalent vaccine in humans to find out."

Dr. Friedman is currently in the process of discussing with pharmaceutical companies the possibility of taking the promising vaccine to clinical trials.
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