By Arj Arjunan
Daily Bruin Contributor
Working to eventually discover an HIV vaccine for humans, UC San
Francisco scientists have developed a vaccine protecting monkeys
from transmitting a virus closely related to HIV.
The virus that the researchers in San Francisco were working
with is Simian Immunodeficiency Virus which can kill a monkey in
under three years.
In studies that lasted for just under a year, Dr. Raul Andino,
an associate professor at UCSF, and Dr. Mark B. Feinberg, a former
assistant professor at UCSF, tested the vaccine, which combines
parts of a widely-used oral polio vaccine with genetic fragments of
SIV. The monkeys that were injected with the vaccine containing SIV
remained healthy for a year.
In recent years, work on a potential HIV vaccine has shifted
focus from developing antibodies in the bloodstream to protecting
the body at the points of infection ““ the mucosal surfaces of
the rectum and genitals.
By using the polio vaccine, the scientists took advantage of its
ability to trigger a strong immune response at the mucosal
surfaces.
The promising outcome has scientists upbeat about prospects for
developing a successful vaccine.
“There is logic in going with something that is
proven,” said Dr. Peter Anton at UCLA’s Center for HIV
and Digestive Diseases, speaking on the use of the polio vaccine.
“The big development is that this had monkeys that showed no
infection.”
Tempering his enthusiasm, he added that the manner in which HIV
mutates makes it difficult to concentrate on any one vaccine.
“No one would take bets because the virus is so difficult
and evolving,” he said.
Charles Price, an associate of Anton, who is currently helping
to organize the volunteer campaign for a similar study at UCLA,
pointed to the close course of SIV in monkeys and HIV in humans as
reason to regard the success of the oral vaccine as promising.
“The promising thing (about the experiment’s
results) is that any oral vaccine takes away the need to have it
professionally administered,” he said, pointing out practical
ways to apply to any potential vaccine.
While the UCSF scientists’ work concentrated on an oral
vaccine, Anton’s work at UCLA currently focuses on whether
different areas of vaccine injection enhance mucosal responses at
the most common site of infection, the pelvic area.
The study tests HIV vaccines based on existing smallpox and
canary pox vaccines. It measures the response of the immune
system’s antibodies and T-cells against the pieces of HIV
present in the vaccines.
Because the vaccines use only pieces of the HIV virus they pose
no risk of infecting volunteers.
Trials on primates indicate that the area of injection markedly
influenced the immune response at the mucosal surface, Anton
said.
So far, the human trials have involved injections in the deltoid
area and now testing focuses on the potential benefits of injecting
in the groin.
Anton suggested that using these vaccines rather than the polio
vaccine promised exposure to more genetic fragments of HIV that
could potentially offer stronger immunity.
“The polio vaccine is smaller, so you can get fewer genes
in there,” Anton said.
Trials at UCLA are still in the first of three phases. Phase one
tests whether vaccines are safe for people to take.
Right now, Price and Faith Landsman, another vaccine trial
organizer working with Anton, are seeking paid volunteers for the
ongoing Experimental HIV Vaccine and Immunology Study.
The trials will take blood samples 15 times over an 18-month
period and involve a sigmoidoscopy that takes sample of rectal
tissue to measure the immune response of volunteers to the
vaccines.
With reports from Daily Bruin wire services.