A-Virus

The Animality virus, also known as the A-Virus, is a man-made mutagenic contagion in the Resident Evil franchise and the central focus of the CGI animated film Resident Evil: Vendetta. This virus was engineered by bioterrorist Glenn Arias as the instrument of his plan to take revenge on humanity for the death of his wife.

History
The A-Virus was developed by Glenn Arias in association with the remnants of the criminal cult Los Illuminados. With it, Arias planned to bring about the end of the human race as atonement for its sins. Three strains of Animality were developed: a Latent strain to be introduced into drinking water, a Trigger strain released in gas form, and a Vaccine that could protect subjects from infection or cure those who had become infected.

Through his dummy company A-GUA Industries Ltd., Arias was able to contaminate the Great Lakes with the Latent A-Virus strain. The contaminated lake waters would be bottled and sold as drinking water across the United States, infecting much of the population. For the first major step in his plan, Arias arranged for a large-scale viral outbreak in New York City, sending multiple tanker trucks containing the airborne Trigger strain to key locations throughout the city. When the gas was released, anyone exposed carrying the Latent strain would mutate into zombie-like creatures and would attack and feed on any uninfected persons in their path. Arias and his agents had been administered the A-Virus Vaccine, so the zombies would ignore them and only target those without the Vaccine.

Arias' scheme was stopped dead in its tracks before New York would fall. The Bioterrorism Security Assessment Alliance dispatched its elite Silver Dagger unit under the command of Captain Chris Redfield and were aided by DSO agent Leon S. Kennedy. Together, they destroyed the tankers dispersing the Trigger gas, minimising the number of infected in the city. After assaulting Arias' base of operations and killing the madman, the BSAA obtained the Vaccine strain and dispersed it across New York, curing the zombified victims and restoring them to normal.

Biology
The Animality Virus refers to three individual viral strains that work in tandem as a biological weapon: the Latent and Trigger Viruses as well as the Vaccine strain.

The Latent Virus is waterborne and transfers from host to host via fluidic contact such as through bites. This strain is naturally dormant, allowing it by design to infect a wide area before detection. Although it could mutate under unknown circumstances, the possibility of this was considerably sparse.

The second strain, the Trigger Virus, is described as causing the Latent strain to activate and zombify its host when the two are in contact. This strain is airborne, and was intended to be stored in gas canisters to be sprayed over a large area. The airborne strain is described as having a similar flash-point to gasoline, making it a highly flammable gas.

The Vaccine strain is notable in that it can reverse the effects of the Trigger virus and un-zombify people. In addition to its cure-like capabilities, the Vaccine strain was also developed so that zombies infected with A-Virus will not attack those vaccinated with this strain.

A true vaccine to the A-Virus was developed at the Alexander University Institute by Dr. Rebecca Chambers with assistance of her fellow researcher Aaron. This vaccination, although capable of eliminating all traces of the A-Virus from one's body, was shown to be unable to prevent later attacks from an A-Virus infected individual.