SAN ANTONIO, Feb. 13 /PRNewswire/ -- Researchers have found new hope in the battle against hepatitis C, the No. 1 cause of liver failure and liver transplantation in the United States. Studies at the Southwest Foundation for Biomedical Research offer the first evidence that a vaccine against all strains of this elusive virus should be possible, since chimpanzees that have previously cleared infection with one strain of the virus show protective immunity to multiple strains.
While a vaccine could be years away, the finding is significant. Scientists previously had thought that prior infection with hepatitis C virus (HCV) only produced immunity to the specific strain with which one had been infected, said lead investigator Dr. Robert E. Lanford of the Southwest Foundation for Biomedical Research in San Antonio (SFBR). Lanford, his colleagues at SFBR, and collaborators at the Johns Hopkins University School of Medicine in Baltimore detail their discovery in an article published in the Journal of Virology for its first edition for the month of February 2004.
Hepatitis C has six different genotypes, or highly divergent groups of viruses, with numerous strains within each genotype. Researchers and pharmaceutical companies have tried for years to develop an HCV vaccine, focusing primarily on genotype 1, the most common genotype in the United States and Europe. But there has been doubt that an HCV vaccine for one genotype could be effective against others.
The discovery by Dr. Lanford’s group that a potential vaccine against one HCV strain could produce protective immunity to multiple strains was based on research with chimpanzees at SFBR’s Southwest National Primate Research Center in San Antonio. Chimpanzees, initially developed by scientists at NIH and SFBR as an animal model for HCV, are the only animals besides humans that can be infected with the virus. As with humans, some chimpanzees maintain chronic infections, while others manage to clear their infection; however, unlike humans, chronically infected chimpanzees do not develop liver disease.
SFBR scientists found that chimpanzees that had cleared previous infection with genotype 1 later showed protective immunity when rechallenged with several different HCV strains. That was true even when the animals were challenged with a highly complex mixture containing strains from genotypes 1, 2, 3 and 4 - the four major genotypes affecting most HCV victims around the world.
Dr. Lanford explained that this finding has significant implications for eventual development of an HCV vaccine “because it means when we are able to make an effective vaccine and immunize a population, people should be protected against all strains of hepatitis C to which they might be exposed.”
In addition to being the No. 1 cause for cirrhosis of the liver, HCV infects an estimated 3 percent of the world population, and accounts for 25 percent of all cases of liver cancer in the United States.
For more information, contact: Julie Collins, SFBR’s director of communications, at 210-258-9437.
Southwest Foundation for Biomedical Research
CONTACT: Julie Collins, director of communications of SouthwestFoundation for Biomedical Research, +1-210-258-9437