BiopharmaReport.com, France
03-05-07
New vaccine technology holds double promise
By Kirsty Barnes
A new nanotechnology-based vaccine delivery method could allow the
development of single-dose vaccines as well as new vaccines in disease areas
of unmet need.
Research presented at last week's ASM Biodefense and Emerging Disease
Research Meeting revealed that a biodegradable polymer in a microsphere
formulation could be used to develop time-released vaccines, thus reducing the
need for vaccine booster shots, as well as stimulate an immune response that
traditional vaccines do not.
"Current vaccines are good at producing antibodies that block entry into the cell.
In the case of some diseases, such as malaria or tuberculosis, antibody vaccines
just aren't effective," said Jenny Wilson-Welder, a lead researcher on the
study conducted at Iowa State University.
The polymer, called polyandydride, is already being used as a delivery system
for a brain cancer drug designed to inhibit tumor growth but this is the first time
its application in vaccines has been shown.
"It's like an everlasting gobstopper or a bar of soap. It wears away slowly over
time, delivering its payload," says Wilson-Welder.
Initially intended to find a controlled-release drug delivery mechanism that would
eliminate the need for booster vaccinations, the study found that polyanhydride
microspheres not only achieved this, but also enhanced a type of immune
response known as cellular-mediated immunity (CMI).
CMI allows the immune system to identify, target and kill cells that have already
become infected, something antibodies can not do.
According to Wilson-Welder, these research findings could lead to the
development of single-dose vaccines for diseases that currently require booster
innoculations in order to be most effective, such as tetanus, whooping cough and
chicken pox.
"The slow release mechanism of the polymers means that vaccines that currently
require multiple doses might only need a single dose in the future," she said.
In addition, the finding that vaccine adjuvants can elicit a CMI provides hope for
vaccines against intracellular diseases that there are currently no effective
vaccines for, like malaria, tuberculosis and even AIDS, said Wilson-Welder.
"If we understand how an adjuvant activates the dendritic cells, we can start
tailoring our vaccines to induce a better cellular response. If we can tailor the
immune response, it holds greater promise for vaccines that we do not currently
have."