Breakthrough Vaccine May Protect Against Herpes Virus

Researchers have created the first vaccine that is effective against two common forms of herpes virus, HSV-1 and HSV-2, according to a recent report.

“We have a very promising new candidate for herpes,” said William Jacobs, PhD, an HHMI investigator at the Albert Einstein College of Medicine.

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In the past, researchers have tried to construct herpes vaccinations based on a glucoprotein called gD—located inside the outer envelope of the virus—that enables the virus to spread from cell to cell. This approach has never proven effective.  

“It was necessary to shake the field up and go another route,” according to Betsy Herold, of the Albert Einstein College of Medicine and co-study leader.

For a separate ongoing study, Jacobs was asked to create a mutated version of the herpes virus that was missing gD altogether.

Though it was not their original intention, once researchers had this mutated strain of herpes virus, “it was a logical, scientifically driven hypothesis to say, ‘This strain would be 100 percent safe and might elicit a very different immune response than the gD subunit vaccines that have been tried.’”

In order to test the viablility of the mutated strain as a vaccine, researchers grew the virus in a cell line that displays the HSV-1 version of gD within the HSV-2 cells.

After researchers introduced the cells into a mouse, HSV-2 used the HSV1 gD to enter the mouse’s cells and replicate, but because the new cells were unable to produce gD, the virus could not spread from cell to cell. This caused infected cells to continue to produce harmless viral proteins that, in turn, caused the immune system to produce antibodies against the infection.

Overall, protection against HSV-1 and HSV-2 was demonstrated, and 4 days after the experiment, no virus could be located, even within mice with severely compromised immune systems.

The potential success of the vaccine could have significant implications for other infections as well, the researchers concluded.

“It’s possible we could clone into this HSV vector pieces of other viruses, such as HIV, and maybe the immune system would produce the same types of [antibody-dependent cell-mediated cytotoxicity] antibodies for those viruses.”

Reference:

Howard Hughes Medical Institute. Radical vaccine design effective against herpes viruses. March 7, 2015. www.hhmi.org/news/radical-vaccine-design-effective-against-herpes-viruses. Accessed March 12, 2015.