Figure I.

Schematic overview of (viral) nucleic acid vectors.

(A) An mRNA molecule contains the coding sequence of the gene of interest (GOI) flanked by a 5′ m⁷G cap-analog and a 3′ poly-A-tail. Similar to the mRNA vector, (B) virus-based replicons encode the GOI but also self-amplification genes, allowing RNA amplification. Both mRNA and replicon vectors are propagation-deficient as they do not encode a complete structural gene cassette. This is in contrast to (C) chimeric and (D) recombinant virus vectors that encode a complete (heterologous) structural gene cassette. These genes facilitate viral propagation, not limiting transduction of the viral vector to a single cell.