Researchers at the
VIDO is the first in
The team, funded by the Canadian Institutes of Health Research (CIHR) and the Canadian Network for Vaccines and Immunotherapeutics (CANVAC), produced a vaccine candidate that decreased the amount of a carrier virus expressing hepatitis C virus (HCV) protein in mice by 100,000 times compared to the control.
"This technique uses the body's own cells, called dendritic cells, to vaccinate against hepatitis C," said Dr. Bhagirath Singh, scientific director of the CIHR Institute of Infection and Immunity.
Dendritic cells are key components of the immune system, activating and shaping the immune response. "The vaccine reduced the amount of hepatitis C protein in a highly significant manner," he said. "This offers a very promising approach to prevent liver disease caused by the virus and to ultimately eliminate it from the body."
About 20 per cent of people who contract HCV overcome the virus on their own. For those who develop chronic hepatitis, the immune system cannot clear the infection.
"In patients with chronic hepatitis C, there is evidence that the function of their dendritic cells is altered," said Sylvia van den Hurk, senior VIDO scientist and member of the research team that developed the vaccine candidate.
"We thought that if we could 'teach' the dendritic cells how to properly activate the immune response and deliver them back to the patient as a vaccine, the patients would clear or at least control the infection."
HCV is the leading cause for liver transplants in the western world, and its annual death toll is expected to triple in the next 10 years. Worldwide, there are about five times more people infected by HCV than with the HIV virus. Treatment of hepatitis C, which like HIV is spread by blood-to-blood contact, is costly and ineffective in about half the patients.
Researchers working in this field have a tough job, says van den Hurk. "The hepatitis C virus is always mutating. For example, one patient can be infected with a strain that spawns sub-strains with different sequences. They are all present at the same time, in the same patient."
The VIDO vaccine uses a viral protein that is common among different strains, ensuring that the vaccine will be effective against them.
The researchers exposed dendritic cells in vitro to a HCV protein. The cells were also exposed to a strong immune stimulator to increase the immune response and then injected into mice as a vaccine. Because HCV does not infect mice, mice were challenged with a carrier virus containing the hepatitis C protein. The levels of HCV protein in immunized mice using this model were five orders of magnitude lower than the control.
Co-authors on the study include Hong Yu, a post-doctoral fellow at VIDO and recipient of a National Canadian Research Training Program in Hepatitis C post-doctoral fellowship award, and VIDO director Lorne Babiuk. Hui Huang and Jim Xiang are members of the Saskatchewan Cancer Agency.