|Romanji||Eirian Enjin Uirusu|
A.E. Virus (A・Eウィルス(エイリアンエンジン), Eirian Enjin Virusu) short for Alien Engine Virus, is a new strain of viral DNA. Viral infection in humans is currently incurable, with a death rate of 100%. Like other viruses, it needs a host because it's unable to independently reproduce. While newer viral strains originate from near-identical older strains, the A.E. virus appears to be unrelated to any viral strains on Earth. The absence of a viral precursor on Earth led to the hypothesis that the A.E. virus originates from Mars. It first appeared 42 years ago, and 20 years ago its number began to rise rapidly.
In order to find a cure and/or create a vaccine, the mission Annex I was initiated to travel to Mars and collect some of the roaches. It is hoped that some of the captured roaches will harbor the A.E. virus, with their bodies being transferred to Earth for further antiviral research.
Though the efforts of the near disastrous mission of ANNEX 1 a vaccine was created from the Terra Formars bodies. The problem is the chance of recurrence is high but a few victims have taken the vaccine and have stayed relatively healthy though their lives.