Anthrax
Anthrax is probably the most likely biological agent. It’s naturally present in the soil, it can easily be produced and can last for a very long time once disbursed. It’s colorless, odorless, and tasteless, and on top of that, it can be produced in a lab, which means it can easily turn into a hidden weapon of mass destruction.
USAMRIID’s efforts against this biological agent include creating an FDA-approved, effective field test for recognizing anthrax. They also made a powerful vaccine that could protect humans from inhalation anthrax which is the one most likely to be exploited as a biological agent and the deadliest form of the infection.