Generation of CTL responses using Kunjin replicon RNA

The Kunjin replicon was used to express a polytope that consisted of seven hepatitis C virus cytotoxic T lymphocyte epitopes and one influenza cytotoxic T lymphocyte epitope for vaccination studies. The self‐replicating nature of, and expression from, the ribonucleic acid was confirmed in vitro. Initial vaccinations with one dose of Kun‐Poly ribonucleic acid showed that an influenza‐specific cytotoxic T lymphocyte response was elicited more efficiently by intradermal inoculation compared with intramuscular delivery. Two micrograms of ribonucleic acid delivered in the ear pinnae of mice was sufficient to elicit a detectable cytotoxic T lymphocyte response 10 days postvaccination. Further vaccination studies showed that four of the seven hepatitis C virus cytotoxic T lymphocyte epitopes were able to elicit weak cytotoxic T lymphocyte responses whereas the influenza epitope was able to elicit strong, specific cytotoxic T lymphocyte responses following three doses of Kun‐Poly ribonucleic acid. These studies vindicate the use of the Kunjin replicon as a vector to deliver encoded proteins for the development of cell‐mediated immune responses.