Spermine compaction is an efficient and economical method of producing vaccination-grade DNA

Plasmid DNA inoculations can induce both humoral and cellular immunity, and this technique is now being employed in developing vaccination regimens for a large number of applications. DNA vaccination studies require the preparation of large amounts of purified plasmid DNA with low endotoxin contamination, and the cost burden for multiple injections, multiple animal or large animal studies is significant. We recently reported that selective compaction with spermine can be used to purify large quantities of DNA. We wanted to determine whether this method would produce DNA suitable for vaccination. Endotoxin levels for spermine-compacted DNA were 0.3+/-0.01 endotoxin units (EU)/microg, well within the accepted range (less than 3 EU/microg) for in vivo use. When injected intramuscularly into mice, column-purified and spermine-compacted DNA induced an equivalent antigen-specific CD8+ T-cell response. The labor and time involved in purifying 5 mg of DNA by each method were similar, but the cost of spermine-compacted DNA was only 20% of the cost of column-purified DNA. We conclude that spermine compaction is an efficient and economical method for preparing vaccination-grade DNA.