Tetanus vaccine comes with a skin cream instead of a needle

If given a choice of vaccine delivery method, would you prefer a needle or a skin cream? thought so. Well, the latter may soon be a viable option, as Stanford researchers have used a topical cream to powerfully vaccinate mice against tetanus.

The key is a bacteria that is almost certainly living on your skin right now: Staphylococcus epidermidis. It is mostly thought to be harmless, but in previous research the team found that it triggers a strong immune response in humans. It appears to be a preventative defense against the microbe entering the bloodstream through everyday cuts and scrapes that break the skin.

“We obtained blood from human donors and found that their circulating levels of antibodies directed against S. epidermidis were as high as anything we are routinely vaccinated against,” said Michael Fischbach, senior author of the new study.

They first performed experiments on mice, which normally do not have S. epidermidis on their skin. When it was dabbed on their heads, the levels of antibodies against the bacteria rose over the next six weeks to levels higher than regular vaccines.

The team wondered if this mechanism could be hijacked as a non-invasive vaccination method against more dangerous pathogens. They found that a protein called Aap on the bacteria’s surface is responsible for triggering antibody production, so the researchers adapted it to display a tetanus toxin.

They repeated the experiment and gave some mice a tetanus-enhanced version of S. epidermidisand others of the ordinary kind. After a few doses on the skin for six weeks, their antibody levels were tested, and sure enough, those who received the bioengineered bacteria showed extremely high levels of tetanus-targeting antibodies.

The final test was to inject the mice with lethal doses of tetanus. All mice that received the bioengineered bacteria remained symptom-free. Even when given six times the lethal dose of tetanus, they survived. Meanwhile, all of them have given the natural version of S. epidermidis succumbed to the infection.

In even better news, it appears that this mechanism can be applied to a wide variety of pathogens. In another test, they swapped the tetanus toxin for diphtheria and found that it also generated a strong immune response in mice. This could end up being a whole new delivery method for many types of vaccines, saving us more than the pain of the needle.

“We think this will work for viruses, bacteria, fungi and single-celled parasites,” Fischbach said. “Most vaccines have ingredients that stimulate an inflammatory response and make you feel a little sick. These errors do not. We expect you won’t experience any inflammation at all.”

As exciting as the research is, it’s important to note that it’s still early days. The next step is to test it in monkeys, the team says, and if it works, human clinical trials will begin in two or three years.

The research was published in the journal Nature.

Source: Stanford University