This brings us to the technique used here. In this case, the researchers placed the antibody genes into a circular loop of DNA called a plasmid. This is enough to ensure that the DNA is not immediately digested and that the antibody genes are turned into proteins. But this does not help DNA penetrate into cells.
The research team, made up of people from a biotech company and academic labs, used a commercial injection machine that combines DNA injection with short pulses of electricity. Electricity disrupts the cell membrane, allowing plasmid DNA to enter the cells. Based on animal testing, doing this in muscle cells is enough to turn the muscles into factories that produce large quantities of broad-spectrum neutralizing antibodies.
A new study was designed to test the safety of such actions in humans. The team recruited 44 participants by testing different doses of two antibody-producing plasmids and injection schedules. All but four subjects completed the study; three of the dropouts tested the program with very fast electrical pulses, which turned out to be unpleasant. Fortunately, this did not seem to affect antibody production.
Although there were many adverse reactions, most were related to the injection itself: muscle pain at the injection site, crusting after the injection, and redness of the skin. The most serious problem was a single case of moderate muscle pain that persisted for several days.
In all but one of the volunteers, the injection resulted in sustained production of two antibodies for at least 72 weeks after injection; the only exception was only one of the two. That's “at least” 72 weeks because that's when they stopped testing – there was no sign that levels were falling at that point. Injecting more DNA resulted in greater variability in the amount of antibodies produced, but the amount quickly reached a maximum level. Increasing the total number of injections also increased antibody production. But even the minimal procedure—two injections of the lowest concentration tested—resulted in the production of significant and stable antibodies.
