Technology evaluation: naked DNA.

: Vical and Merck are investigating vaccines against hepatitis B which use Vical's patented naked DNA technology. Both therapeutic and prophylactic vaccines are under development [177132], [268397]. The technology, and subsequent collaboration, stems from the observation by Vical that by directly injecting exogenous cDNA into muscle tissue, protein is expressed which gives rise to a strong immune response and protective immunity [163222].