Unicron virus

Wacky colors? Be happy it didn't make that hair fall out, pal.

The Unicron virus is a nanotech pathogen that is seen to affect Transformers inside Unicron's body during the Universe War. It is accompanied by "Unicron radiation"; the distinction between the two is unclear. An exposed Transformer will experience changes both mental (an upswing in negative emotions) and physical (discoloration). Repeated exposure can lead to madness and death, the only known cure being reformatting by Primus or the Matrix of Purification.

Fiction

3H comics

Another figurative statement made literal by the power of retcon!

When Silverbolt, Blackarachnia, Roulette, Shadow Striker, Trailbreaker, Sideswipe, and Sunstreaker were teleported from the technorganic Cybertron into Unicron's body, they immediately began to sense his corruptive influence. Blackarachnia said she could "feel it invading [her] spark like a virus." They were all then plunged into the fire of the Pit, and many of them came out entirely restructured. Abduction Blackarachnia soon turned entirely back to her Predacon ways and joined Unicron's Minions. When Optimus Primal infiltrated Unicron to rescue them, he quickly felt the corruption as well, though he referred to it as a "radiation". It discolored him, but that was the extent of its initial effect. Escape

After Optimus Primal rescued the dozens of Transformers abducted by Unicron, and brought some of them home to his own universe's Cybertron, work began on attempting to cure the virus. At the Oasis Research and Development Facility, Ratchet, with help from Striker and others, experimented on the survivors. However, the virus mutated quicker than Ratchet was able to make progress. Ratchet bemoaned why he was sent to this universe, rather than back to his own after Primal's rescue attempt, like most of the others. Trailbreaker suggested that he might have been chosen by Primus to help eliminate the virus. Homecoming

Sideswipe and Sunstreaker were cured of the virus by being put back in their G1 forms! Hooray?

As Optimus Primal returned to raid Unicron again and again over the course of the Universe War, these multiple exposures to the virus took their toll. When he and several of his allies, such as Cheetor, began to succumb debilitatingly, Primus reformatted them, rendering them completely resistant to both the virus and the radiation. Primal's new form contained the Matrix of Purification, which could heal and reformat those suffering from various ailments, including Unicronian corruption. Beast Wars 10th Anniversary Optimus Primal's profile.