Probiotics have been getting quite a bit of attention of late. By definition, they are “live microorganisms which when administered in adequate amounts confer a health beneﬁt on the host.” This rather vague definition has led to a host of potential benefits ranging from better digestion to improved weight management and even better mental health. But until recently, no one has mentioned vaccines. Yet, a probiotic oral vaccine may one day be our route to protection against infection.
The best candidate for an oral vaccine is known as Lactobacillus acidophilus. It was discovered almost a century ago and has been thoroughly examined in the lab. You can usually find this bacterium in fermented milk products but it can be found in a variety of other places, including the human body. It can live on our teeth, in our guts, and for women, in the vagina.
Because L. acidophilus is tolerated by our bodies, researchers have believed it communicates with the immune system in a friendly manner to prevent any defensive attacks. When this was tested in 1997, the bacterium definitely had an effect in humans. But surprisingly, instead of keeping the immune system calm, the cells involved in immunity became more active; just not against the bacteria.
Improving (or if you will, boosting) immunity might seem like a great selling point but for the researchers, this meant the bacterium could have a much greater role in another area of health: vaccines. Instead of using chemicals to improve the immune response, one would simply ingest acidophilus bacteria. In 2008 this was tested in pigs using an oral rotavirus vaccine.
Sure enough, once the bacteria were ingested, the immune response was enhanced and led to even protection against the viral pathogen.
But this wasn’t the end of the story. In 2011, the involvement of probiotics in vaccines took another leap. This time, instead of adding bacteria to a vaccine, the acidophilus would actually be the vaccine.