New information about HSV-2 Vaccinations

(Montana State University (2006, October 16). Research Holds Promise For Herpes Vaccine. ScienceDaily. Retrieved March 20, 2008, from http://www.sciencedaily.com/releases/2006/10/061013201826.htm)

Research done by Montana State University poses a new possibility in the development of a vaccination for HSV-2 and other diseases that are related to the herpes simplex virus.

MSU virologist William Halford found that mice vaccinated with a live, genetically-altered strain of HSV-1 showed no signs of disease 30 days after being subjected to a lethal "wild-type" strain of the virus. His findings were published earlier this year in the Virology Journal.

However, Halford found that, a second group of mice to whom he administered a more common vaccine died within six days of being subjected to the identical lethal "wild-type" strain as the first group.

Halford, who works in MSU's Department of Veterinary Molecular Biology, said, "[There is] a clear roadmap for a live vaccine … my studies were performed with HSV-1, [but] the implications for HSV-2-induced genital herpes are clear. Overall the …viruses are…[genetic equivalents]."

About 55 million people in the U.S. have HSV-2. Genital herpes is incurable, which means that the infection is life-long. Roughly 5% of those with genital herpes – 2 to 3 million people in the U.S. – experience genital herpes outbreaks one to four times a year. There is no vaccine that provides life-long protection from genital herpes.

The foundation of Halford's research was a deep knowledge of how the herpes simplex virus attacks the body's natural defenses against the virus.

A herpes simplex infected cell alerts neighboring cells in the body in a process called an interferon response, which triggers neighboring cells to go into "an anti-viral state" which is the equivalent of putting on a suit of armor to defend themselves from herpes.

However, the herpes virus makes a protein known as, ICP0 that essentially “fools” each herpes-infected cell into destroying its own defenses. With the cells’ armor destroyed, the virus can multiply and begin attacking neighboring cells and this cycle continues throughout the cells of the body.

In his experiment, Halford made a vaccine that interrupted the genetic instructions that create the ICP0 protein. When these instructions were inhibited, the virus could still infect the mice, but the spread of the herpes virus to other cells is prohibited before disease has a chance to be spread.

Halford shows that "…we can disarm the virus [and make it] unable to cause disease, [while being a viable] …a vaccine.”

In humans, we would take out the genetic instructions for ICP0 just like in Halford’s mouse experiment, which would create an "attenuated," or weakened virus. The remainder of the herpes simplex virus' genetic code would remain intact. Other vaccines that are produced from weakened viruses include measles, mumps, rubella, polio and yellow fever.

The latest research in this area, however, has focused primarily on subunit vaccines--vaccines created from one part of a virus. Subunit vaccines carry less risk than attenuated virus vaccines because it is impossible for a subunit to replicate or cause disease. But, unfortunately, subunit vaccines do not protect against chronic viruses like genital herpes and AIDS, Halford said.

"[Theoretically] subunit vaccines are poor … natural virus infection," Halford said. "There's not enough… to build a protective response..."

Halford, who is 38, knows that critics view his stance on the herpes virus as controversial.

"… I'm young .. I don't know how long it can take to [influence] scientists and clinicians," he said. "I …hope that … the scientific community would …consider these proposals."

To perform further research on a human herpes vaccination, Halford is seeking a commercial partner or secure government funding. "I'd like to take this concept … to the clinics," he said.