One of the rites of childhood could soon become a thing of the past: the vaccination shot. Researchers have found that in mice, at least, vaccines made of pure DNA can be absorbed through the skin and provoke an immune response similar to that of standard vaccines. If the technique works in humans, immunizations could be given cheaply and easily via a patch or a Band-Aid.
"I'm from China, where a lot of people can't afford to get vaccinated," says Hongran Fan, an immunologist at Stanford University. "If you make vaccines easier to apply, more people will get them." Besides, says Jonathan Vogel, a researcher in the dermatology branch of the National Cancer Institute, "the skin is a good organ to target" for vaccine delivery. Because the skin is a front line against microbes, he says, it has many more immune cells that latch onto foreign proteins and deliver them to the lymph nodes, where other cells produce antibodies to mount an immune response.
In the September issue of Nature Biotechnology, Fan and Stanford pharmacologist Paul Khavari describe how they swabbed five mice with a solution containing bacterial DNA spliced with a gene from the virus that causes human hepatitis B, and gave five others an injection of a conventional protein-based vaccine against hepatitis B. After 4 weeks, the swabbed mice had produced about a third as many antibodies against hepatitis as had mice given the injection. The big question, says Fan, is whether that immune response is strong enough to protect against disease. So far it's impossible to know for sure, because mice don't get human hepatitis.
If further tests show that the new vaccine method works, it will have some big advantages over standard injections, says Vogel: DNA vaccines are easier to mass-produce than protein-based vaccines and do not spoil at room temperature. Stephen Johnston of the University of Texas Southwestern Medical Center at Dallas, a pioneer in DNA vaccines, agrees: in another generation, he says, "it's almost a sure bet that we will not be doing intramuscular injection of [childhood] vaccines."