Previously, we described the efficacy of immunisation with recombinant Semliki Forest virus (SFV), expressing the human papillomavirus 16 (HPV) oncoproteins E6 and E7, in inducing HPV-specific CTLs and anti-tumour responses. Recently, we developed a novel recombinant SFV construct encoding a relatively stable fusion protein of HPV16 E6 and E7 under control of a translational enhancer derived from the SFV capsid protein. In the present study we demonstrate that immunisation of tumour-bearing mice with this improved vector results in the regression and complete elimination of established tumours. We furthermore demonstrate that a long-term high level of CTL activity, up to 340 days, accompanies the anti-tumour response. Thus, immunisation with recombinant SFV particles encoding increased levels of a fusion protein of HPV16 E6 and E7 efficiently induces CTL activity and CTL memory resulting in a potent therapeutic anti-tumour effect.
Copyright 2002 Elsevier Science Ltd.