The infamous “bubble boy,” David Vetter, was born in Texas in 1971 with severe combined immunodeficiency (SCID). He lived his entire life inside a sterile plastic bubble, unable to have contact with the outside world or other humans due to a defect in his immune system, which left him vulnerable to serious infections.

Back then, there wasn’t much doctors could do to stop or mitigate the immune disorder — so David had to stay inside his bubble, or wear a plastic “space suit,” until he died at age 12 from lymphoma. Bone marrow transplants were one way to treat the disorder, and more recently, gene therapy has been used to treat various types of SCID. So far, doctors have fixed the immune systems of some 17 children who’ve suffered from ADA-SCID and X-SCID, two different forms of the disease. But being able to identify the disease early on is still in the works among researchers.

Now, a new study out of Virginia Tech has pinpointed a potential biomarker in gut bacteria that could help doctors diagnose SCID early on and help treat infants as soon as possible. Plenty of studies have shown that gut microbes are essential in keeping a balance in our stomachs and immune systems. “This is an interesting finding because it means we can potentially screen for this microbe at an early age to find defects in the immune system,” Xin M. Luo, assistant professor of immunology at Virginia-Maryland College of Veterinary Medicine, said in the press release.

David Vetter's spacesuit
Thanks To David Vetter, doctors were able to learn a lot more about SCID to better treat future children. Wikimedia / NASA

In the study, researchers compared gut microbes in healthy mice to those with an impaired immune system — both before and after weaning. The mice with a defective immune system had more of a microbe known as Akkermansia muciniphila, which is “also a human intestinal microbe,” Husen Zhang, research assistant professor in the Department of Civil and Environmental Engineering in the College of Engineering, said in the press release. “Although it is rather newly discovered, it has been there for a long time. Previous reports found that the microbe increases with antibiotic use, indicating that it might thrive when other gut microbes don’t survive a round of antibiotics.”

After bone marrow transplants, though, the mice’s levels of the microbe were reduced to normal. “There have been many studies recently on how gut microbes modulate the immune response, but we wanted to do the opposite,” Luo said in the press release. “We are asking the question, ‘How does our immune system affect bacteria in the gut?’”

SCID is a rare disease, only affecting some 0.1 percent of the human population, but it’s so severe that most children usually die within their first year if it goes undetected. This is because infants will usually experience bad infections from bacteria, viruses, or fungi.

“If SCID is not detected, children cannot live past their first year,” Luo said in the press release. “Now, we may have a noninvasive way to screen for this disease because this microbe may be present only in negligible amounts in healthy, young children. If larger populations of the microbe are present, quick examination is needed to prevent a potentially deadly emergency.”

Source: Zhang H, Sparks J, Karyala S, Settlage R, Luo X. “Host adaptive immunity alters gut microbiota.” The ISME Journal. 2014.