The Beast Virus is a virus that can infect Metal Cardbots and make them go berserk. It is carried by Wild Cardbots from creation¹², and is first shown to infect Blue Cop in S3E1, Era of Change, turning him into Blue Cop W.

Effects

When a Metal Cardbot is infected with the Beast Virus, they lose control of their actions and grow beastly features.^{[citation needed]} It is possible for the infected Cardbot to regain control of themselves, but their transformations will remain, and they are prone to going berserk again (such as in the presence of Tyrant Zero). Fully infected Metal Cardbots lose their memories from before their infection.^{[citation needed]}

Curing the virus

The only known way to cure the virus is to contain it within a Cardbot’s Weapon Card,³ such as by using a specialized Metal Breath. Variants developed by Bloodwing can be purified using the light of the sun, such as through Grand Blue Leon.⁴

It is unknown if there are any ways to reverse the animalistic changes caused by the virus.

The virus can be prevented from spreading by injecting a Metal Cardbot with a vaccine developed by Crest and Buster Gallon, but this does not work against variants of the Beast Virus developed by Bloodwing.

Metal Cardbots infected with the Beast Virus

Note that Savannard‘s infection works differently from other Cardbots, possibly since he was possessed instead of infected.⁵

• 

  
  Fleta Z
• 

  
  Buffalo Crush
• 

  
  Musclehyde
• 

  
  Gigantrex
• 

  
  Sky Gallop
• 

  
  Deep Bite
• 

  
  Blue Cop W
• Heavy Iron W
• 

  
  Bloodwing
• Savannard