Herpes Vaccine Found to Shield Some Women from HSV-1
Investigators at the Saint Louis University Center for Vaccine Development are expressing cautious optimism regarding a treatment of one of two types of genital herpes found in women, according to a study in the New England Journal of Medicine.
Dr. Robert Belshe, director of the center and lead author of the study, said the investigational vaccine was partially effective at preventing herpes simplex virus type 1, (HSV-1) in women, but did not protect them from herpes simplex virus type 2 (HSV-2). He said more than 8,000 women participated in the trials funded by the National Institutes of Health in Washington, D.C.
"There is some very good news in our findings. We were partially successful against half of the equation -- protecting women from genital disease caused by HSV-1," said Belshe. "It's a big step along the path to creating an effective vaccine that protects against genital disease caused by herpes infection. It points us in the direction to work toward making a vaccine that works on both herpes simplex viruses."
The herpes simplex virus is one of the most stubborn diseases for physicians to treat because once inside the human body it remains there permanently with no known cure available. It is also a very common communicable disease infecting at least 25 percent of women in the United States and causing neurological disease and even death in infants born to women with the condition. The virus is a risk factor in the sexual transmission of HIV.
Belshe said the clinical trials were conducted at 50 locations in the United States and Canada involving 8,323 women between the ages of 18 – 30 who did not have either of the herpes viruses. The National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, funded the study. The women received three doses of the investigational herpes vaccine and then were evaluated over 20 months for any occurrence of genital herpes. The participants were also given blood tests to determine if an infection with either of the herpes viruses occurred during the trial, the Journal story reported. As a result, the researchers found that two to three doses of the vaccine protected women against HSV-1, but did not shield women from HSV-2.
"We were surprised by these findings," said Belshe, who also is a professor of infectious diseases and immunology at Saint Louis University School of Medicine. "We didn't expect the herpes vaccine to protect against one type of herpes simplex virus and not another. We also found it surprising that HSV-1 was a more common cause of genital disease than was HSV-2."
Studies regarding the spread of sexually transmitted diseases have concluded HSV-1 is a common cause of the spread of genital herpes because more couples are engaging in oral sex. Both HSV-1 and HSV-2 are members of the herpes virus family. Typically, HSV-2 causes lesions and blisters in the genital area while HSV-1 generally causes sores in the mouth and lips, although it increasingly has been found to cause genital disease as well.
Researchers are conducting laboratory tests on serum obtained from the participants as they continue to study why the vaccine protected women from genital disease caused by HSV-1 and not HSV-2. One hypothesis, Belshe said, is HSV-1 is more easily killed by antibodies than is HSV-2. This means that the vaccine antibodies might work better against HSV-1 and result in protection from HSV-1 but not HSV-2, he said.
Reference: Saint Louis University School of Medicine
Investigators: Robert B. Belshe, M.D., Peter A. Leone, M.D., and others for the Herpevac Trial for Women
N Engl J Med 2012; 366:34-43