VAXXING GONE SWABBING: How scientists “turned” bacteria into vaccine creams

We often associate vaccines with needles and syringes—tried-and-tested tools for immunization. But imagine swapping those needles for a simple cream applied to your skin.

Researchers at Stanford University have recently published their study on a pervasive bacteria living on the human skin known as Staphylococcus epidermidis. These particular skin-inhabiting bacteria can stimulate a certain type of immune cell in the body even without an infection.

This research, entitled “Discovery and engineering of the antibody response to a prominent skin commensal,” was published in Nature on December 11, 2024.

In their research, the researchers put to the test the underrated potential of S. epidermidis, and with some ingenious engineering, they managed to amplify its immune-activating ability, adapting to certain diseases by sampling their toxins into its gene.

The human skin is teeming with microbes, most of which are harmless. Among them is S. epidermidis, now seen as a revolutionary player in immunology.

By performing initial testing of head-swabbing on mice, the researchers have been able to indicate the ability of S. epidermidis to provoke powerful and long-lasting antibody responses in an organism. 

The culprit to this phenomenon is a protein called accumulation-associated protein (Aap), and it triggers the increase in antibody levels whose effect is the same as getting vaccinated.

Having identified the antibody-stimulating properties of Aap, researchers modified the protein by genetically encoding a fragment of a particular disease, such that S. epidermidis would trigger a larger boost of antibodies in defense to that kind of infection. In the case of the experiment, they encoded tetanus toxin.

Over a six-week period, mice swabbed with the modified bacteria produced high levels of antibodies. When later exposed to lethal doses of tetanus toxin, only the swabbed mice survived, while those treated with unaltered bacteria succumbed.

Further findings of the researchers showed the same effectivity even if applied after only 2 to 3 swabs. Additionally, this experiment was done similarly with the gene for diphtheria toxin and likewise showed similar findings. 

Unlike mice, humans naturally harbor S. epidermidis on their skin, making this approach even more promising. Early trials revealed no interference from existing skin bacteria, and researchers are optimistic about future tests on primates.

Dr. Michael Fischbach, one of the study’s senior authors, expects clinical trials in humans could begin within two to three years if results remain positive.

Without costing a needle, this endeavor implicates imperative topical findings in the field of vaccinations. 

While there are high hopes of probing for groundbreaking medical innovations, searching may often come ambiguous, for what’s expected to be found in the deep abyss of tissues can be uncovered beneath the shallow surface of the skin.