Science

Hepatitis C virus-like particles induce immune responses in baboons

Last Updated: 2004-08-03 11:25:24 -0400 (Reuters Health)

By Will Boggs, MD

NEW YORK (Reuters Health) - Hepatitis C virus-like particles (HCV-LP) induce both humoral and cellular immune responses in baboons, according to a report in the July Journal of Virology.

Virus-like particles are noninfectious proteins that closely mimic the properties of native virions, the authors explain, and HCV-LP have previously been shown to induce virus-specific immune responses in mice.

Dr. T. Jake Liang from National Institutes of Health, Bethesda, Maryland and colleagues evaluated the safety and immunogenicity of HCV-LP in a baboon model.

Immunized baboons showed a 100% seroconversion rate after the fourth immunization, the authors report, and the seroconversion rate after the third immunization increased from 0% to 100% with the use of adjuvants.

HCV-LP immunization also induced HCV-specific CD4+ and CD8+ T-cell responses, the report indicates. These responses were not significantly enhanced by the addition of adjuvants to the vaccine.

Boosting at 8 months markedly enhanced both humoral and cellular immune responses. "This suggests that boosting after an extended period of hiatus from the previous immunization is likely to be crucial in the activation and expansion of memory T- and B-cell responses to elicit a robust and long-lasting immune response in these animals," the investigators write.

HCV-LP immunization appeared to be superior to immunization with recombinant HCV vaccinia virus, the researchers note.

All baboons remained healthy without any signs of toxicity from the immunization or adjuvants.

"The scientific community is working very hard to advance our knowledge in the prevention and management of hepatitis C," Dr. Liang told Reuters Health. "Development of an HCV vaccine is possible."

Dr. Liang added, "We are testing this approach in chimpanzees now."

J Virol 2004;78:6995-7003.