Heterologous and Homologous Protection Against Influenza A by DNA Vaccination: Optimization of DNA Vectors

TLDR

The authors engineered plasmid vectors based on a pUC‑19 backbone with CMV IE1 enhancer, promoter, intron A, and BGH polyadenylation to express either CAT, influenza A nucleoprotein, or hemagglutinin, and optimized them for high‑yield production in *Escherichia coli*. The optimized vectors produced high levels of CAT and NP, yielded 14–15 mg plasmid per liter, and conferred protection in mice against lethal heterologous and homologous influenza A challenges.

Abstract

We have recently shown that direct injection of DNA can be an effective vaccine strategy eliciting both humoral and cell-mediated immune responses. Vectors were designed specifically for vaccination by direct DNA injection and refined to improve plasmid production in Escherichia coli. The vectors consist of a pUC-19 backbone with the cytomegalovirus (CMV) IE1 enhancer, promoter, and intron A transcription regulatory elements and the BGH polyadenylation sequences driving the expression of the reporter gene CAT or influenza A nucleoprotein (NP) or hemagglutinin (HA). The respective vectors expressed high levels of chloramphenicol acetyltransferase (CAT) and NP in tissue culture, and yielded 14-15 mg of purified plasmid per liter of Escherichia coli culture. Immunization of mice with the NP and HA expression vectors resulted in protection from subsequent lethal challenges of influenza using either heterologous or homologous strains, respectively.