This is how Ultra Magnus is infected goes in Cybonic Plague.
[At the Autobot base]
Starlight Glimmer: [grunts as she tries to levitate Bulkhead]
Trixie: Go on!
Discord: You can do it!
[Starlight levitates Bulkhead]
Thorax, Trixie and Discord: [cheer]
Ratchet: Guys! I've just pinpointed the Changeling Castle.
Trixie: Let's check it out.
Optimus Prime: It may be dangerous. Ultra Magnus and Starlight will come with you.
Starlight Glimmer: Wait! [points a ship on the screen] What's that?
Ratchet: Also on the same frequency, an Autobot emergency beacon.
Ultra Magnus: Then we must check it out immediately.
[Ultra Magnus, Starlight, Trixie, and Ratchet groundbridge to the ship's location]
Ultra Magnus: A crash landing. Buried here for centuries.
Starlight Glimmer: Whoa!
Trixie: Tha's a big one.
[Ultra Magnus cuts a hole in the wall]
Ultra Magnus: Stay cautious.
Ratchet: If they traveled in stasis mode, there may be survivors.
[The ship shakes]
Starlight Glimmer: What is that?
Ratchet: Stay close.
[They come to a door]
[Ultra Magnus, Starlight, Ratchet, and Trixie enter the control room only to find dead Autobots]
Ratchet: Guys these Autobots didn't perish in the crash! They're displaying the effects of a virus!
Ultra Magnus: This is a plague ship.
Starlight Glimmer: What?
Ratchet: Don't touch anything. The virus could still be active.
[The ship shakes again and an Autobot on the ceiling leaks plague on Ultra Magnus making him wrive in pain]
Starlight Glimmer: Ultra Magnus!
[Transformers Prime theme plays]
[Transformers Prime theme ends]
Ratchet: Cybonic plague. It's only contagious if contact is made with the infected Energon.
Applejack: What was a plague doing in an Autobot spaceship?
Ratchet: Its passengers were infected. The virus wiped out millions on Cybertron during the Great War. Cybonic plague was engineered in the Cybertronians' biological-warfare program by Unicron himself.
Rarity: You have a cure, don't you?
Ultra Magnus: [groans] No cure.
Optimus Prime: Ultra Magnus, please, save your strength.
Rainbow Dash: Would Unicron create a disease without having a cure? I mean, what if he caught it by accident?
Smokescreen: It's not like we can ask Unicron.
Fluttershy: You think it's possible Unicron told Thunderwing the cure?
Ratchet: We could just infiltrate the Changeling Castle and look for the cure. After all we still have their location pinpointed.