Characterization of a messenger RNA polynucleotide vaccine vector.

TLDR

This strategy might be particularly useful to induce an immune response to a proto‑oncogene product or growth factor that poses a risk of malignant transformation due to prolonged protein expression. The study examined the feasibility of using the mRNA vector as a tumor vaccine after demonstrating protein expression in vitro and in vivo. The authors constructed capped, polyadenylated mRNA transcripts encoding luciferase or CEA stabilized by human beta‑globin UTRs, and administered 50 µg of CEA‑encoding mRNA intramuscularly twice weekly for five weeks to seven mice before challenging them with syngeneic CEA‑expressing tumors. The mRNA constructs mediated luciferase expression in vivo and CEA expression in vitro, and the vaccination schedule primed an anti‑CEA immune response, with five of seven immunized mice developing anti‑CEA antibodies after tumor challenge while controls did not.

Abstract

We have constructed mRNA transcripts encoding luciferase and human carcinoembryonic antigen (CEA) which are capped, polyadenylated, and stabilized by human beta-globin 5' and 3' untranslated regions. The mRNA construct encoding human CEA directed CEA expression in mouse fibroblasts in vitro following liposome-mediated transfection. The luciferase encoding mRNA transcripts mediated luciferase expression in vivo following i.m. injection. Based on the demonstration of protein expression in vitro and in vivo, the feasibility of using such a vector as a tumor vaccine was examined. In this pilot study, seven mice received 50 micrograms mRNA transcripts encoding CEA twice weekly for 5 weeks by i.m. injection followed by challenge with syngeneic, CEA-expressing tumor cells. This dose and schedule "primed" an immune response to CEA. Five of seven mRNA-immunized mice demonstrated anti-CEA antibody 3 weeks after tumor challenge whereas control mice had no evidence of antibody response. This strategy might be particularly useful to induce an immune response to a proto-oncogene product or growth factor which poses a risk of inducing malignant transformation consequent to prolonged protein expression.