Transformation virus
From MediaWiki
The Transformation lock virus is precisely what its name implies, a virus that prevents a Transformer from leaving its altmode. By transmitting this virus all over Cybertron, Megatron (BW) was able to take the sparks of the planet's inhabitants and use them as fuel for mindless drones. When the Maximals returned to Cybertron, they were unable to transform because of this virus and were forced to find a techorganic form that was less susceptible to the virus. After the Oracle reformatted Optimus Primal, he did the same to his followers, making them immune to the effects of the virus.
