Virus

''The monkeys have managed to turn a horrible disease into something that can pop Bloons. The virus will spread across from Bloon to Bloon, allowing for major Bloon poppage!''

The virus is a special agent that costs $70 monkey money. It can be used on any round, and is used by applying it to a Bloon, however M.O.A.B. class Bloons are not affected. The virus takes 3 seconds to take effect, but once it does, the Bloon will get sick, will lose one layer per second, and will be slowed down to half speed. Additionally, any Bloons touched by infected Bloons will also become infected, with the same effect. These Bloons can infect other Bloons, and so on. Bloons inside infected bloons are also infected. The virus only stops if all infected Bloons on screen get popped.

Pro
''Pro upgrade- M.O.A.B. eating viruses! The monkeys have discovered how to improve the damage of the virus! Now the virus can corrode into the skin of M.O.A.B. class Bloons, along with doing 2 damage per second to Bloons!''

After 50 uses, the pro virus is unlocked. It corrodes away the skin of M.O.A.B. class Bloons (Doesn't slow them down, though), and does twice as much damage to all Bloons!