A research team from Harvard Medical School recently revealed how the body’s immune system responds to the presence of anthrax spores.
Anthrax bacterium, called Bacillus anthracis, was used as a weaponized chemical agent in 2001, when a series of letters coated in the chemical agent were sent to two Democratic senators and various national news media offices. The attack resulted in the deaths of five people while injuring 17 others. In response to the event, a number of anthrax vaccine dosages are stored in the U.S. Strategic National Stockpile in the event of another bioterrorism incident.
The Harvard study found that the body’s immune system first detects the presence of anthrax by recognizing RNA molecules that coat anthrax spores’ surface. This process then prompts a poor immune response that harms the body’s fight against anthrax once the spores have developed into live bacteria.
“It is unclear whether anthrax spores trigger host immune responses and, if so, which components of the spore activate host immune sensors,” Jin Mo Park, professor of dermatology at Harvard and lead author of the study, said.
The researchers also found that the presence of anthrax spores stimulates the immune system and does so by activating a specific set of immune sensors that don’t recognize the vegetative, or active, form of Bacillus anthracis.
Park’s team suggested that Bacillus anthracis evolved to use a spore associated with RNA to activate immune-signaling molecules called type I interferons which help them evade host immunity.
“Our findings suggest that spore-associated RNA triggers early host responses to anthrax infection, but that type I interferon signaling serves to misguide host immunity and impair the body’s defense against the vegetative form of the bacterium at later stages of infection,” Park said.