TUESDAY, April 15 (HealthDay News) -- Researchers say they've
created a synthetic vaccine that can be delivered as a nasal spray
for human papillomavirus -- the source of the most common sexually
transmitted disease in the United States and a cause of cervical
cancer.
The experimental vaccine, tested so far just with mice, also
offers protection against different strains of HPV, the researchers
said.
The existing vaccine for HPV, called Gardasil, protects against
four strains of the virus that are responsible for about 70 percent
of all cervical cancers. The Gardasil vaccine requires three
injections for full protection.
"We have been trying to produce a single vaccine that would be
able to protect patients against all cancer causing HPV types,"
said Richard B.S. Roden, lead researcher for the new study and an
associate professor of pathology, gynecology and obstetrics, and
oncology at Johns Hopkins University.
"What we have done is to try to develop a completely synthetic
vaccine that would induce antibodies that would neutralize and
protect against a whole range of these cancer-causing strains," he
added.
The advantages of the synthetic vaccine are that it can be
synthesized as if it were a drug, Roden said, adding that "it can
be made chemically in the lab rather than having to use biological
systems."
A synthetic vaccine also should be cheaper, Roden added. Using
this approach, the vaccine could also be given nasally, he
said.
"This may be another way to reduce the cost of vaccination,
because you don't have to use needles," he said.
The findings are published in the April 15-18 issue of the
Proceedings of the National Academy of Sciences.
In their experiments, Roden and his colleagues used a protein
from one of the strains of HPV -- HPV16 -- to create a man-made
vaccine in the laboratory. When the vaccine was given to mice
either by injection or nasal spray, it protected not only against
HPV16, but also against another strain of the virus -- HPV45.
Roden said the mice used in this experiments had special immune
system T helper cells for the vaccine to attach itself. Whether
human T helper cells would work in all groups of people isn't
known, he said. "Right now, that's an area we are looking at," he
said.
HPV is responsible for genital warts and about 99.7 percent of
all cervical cancers worldwide.
Debbie Saslow, director of breast and gynecologic cancer at the
American Cancer Society, said that if this vaccine could be
developed, it would represent an important advance in getting more
people vaccinated against HPV, especially in developing
countries.
"While we have wonderful opportunities with the current vaccine,
there are limitations," she said.
One limitation is the cost of the Gardasil vaccine, an estimated
$300 to $500, Saslow added. "That's a limitation in this country,
but particularly in the developing world where there is so much
cervical cancer," she said.
The Gardasil vaccine also requires three shots, which is
difficult in developing countries and among adolescents, Saslow
said.
"Needle-less vaccination is the way to go for a lot of reasons,"
she said. "The current shots are extremely painful, and that's
going to be a deterrent for teenage populations, as is going back
and getting the three doses."
More information
To learn more about HPV, visit the
U.S. Centers for Disease Control and Prevention.
