The life cycle of a normal virus can be described through the T-bacteriophage, a virus that preys upon bacteria. The virus itself is a protein crystal with a DNA core. Once the crystal touches a bacteria's cell membrane, it dissolves and allows the viral nucleic acid to enter the cell. The cell immediately absorbs the viral genome into its own DNA. The new genes take over the cell's functions and the cell manufactures dozens of new viral crystals and DNA strings. These crystal shells combine with the new DNA copies to form new viruses; the viruses dissolve the host cell, infect neighbouring cells and begin the cycle all over again. All cell energy in the human body is created by mitochondria. The T-virus actively kills any living mitochondria and replaces the dead ones. The T-virus then combines with cells to produce energy; this energy is enough to power the motor neurones and basic lower brain functions. This bypasses the entire circulatory system and makes organs such as the heart and lungs redundant. Unfortunately the T-virus must consume the cell in order to produce this energy and to divide mitotically and spread round the body. The slow breakdown of cells leads to the necrotising effects seen on most BOWs. The virus also incorporates itself into the host’s RNA substantially altering it. It is in this way that creatures lower down the evolutionary ladder, such as insects, birds and reptiles only increase in size and have only minor mutations due to the relative simplicity of their genome structure.

Also known as the Founder virus and the Mother virus, the Progenitor virus was the very first mutagenic virus ever discovered, and would serve as a base for most of Umbrella’s later viruses. It was discovered by Dr James Marcus, Dr Edward Ashford and Lord Oswell E. Spencer on December 4th 1967. Further research on it was carried out by Dr. Marcus, William Birkin and Albert Wesker. Infection causes violent uncontrolled cellular changes through the mutation of the subject’s genes. Like the T-virus this will cause most animals low down the evolutionary ladder to simply increase in size and aggressiveness, but the mutations were not coordinated enough to produce effective BOWs. In order to enhance its mutagenic properties a variant of it was created by combining it with the Ebola virus. Unfortunately the new virus had inherited Ebola’s photosensitive properties. When it was combined with leech DNA to form the T-virus this property mutated into pyrosensistivity, which can be seen to affect every single BOW ever created.

The NE-T virus has very similar properties to the T-virus, but it was designed specifically in relation to the Tyrant Project. In response to reports of the T-002’s failure, a new project was started. Its original goal was to ensure the destruction of all anti-umbrella elements, specifically STARS members. It was given the grandiose title of ‘Goddess of Vengeance’. The research team though nicknamed the project Nemesis, as they held the surviving STARS members directly responsible for the T-001 and T-002’s failure and took a certain satisfaction in working on a project designed specifically to eliminate them, and the name stuck. Research pertaining to a similar project had been started a few years ago when Umbrella researchers were looking to improve the general intelligence of BOWs. So far all T-virus created BOWs had had extremely low intelligence ratings. Umbrella needed a BOW that could understand and carry out orders. The American team led by Dr. Birkin was working on ways to increase the BOWs’ strength, whilst the European team was working on ways to increase the BOWs’ intelligence. Countless theories and ideas were traded and they first started experiments that involved directly operating on the subject’s brain. Birkin’s team succeeded in creating the T-002, which unlike the highly unstable T-001 could follow the simplest of orders such as ‘restraint’ and ‘attack’. But its intelligence was still insufficient for the BOW to operate in the field. Then a breakthrough by the European team came in the form of the NE-Alpha, an independent organism created from the NE-T virus that could affect the host’s brain. Further experiments were made, including inserting the NE-Alpha into a Hunter. It was this experiment that provided crucial data that led to the creation of the T-103.

G-Virus The G-virus was discovered by Dr William Birkin in the Arkley labs on July 1st 1988. The Arkley labs had obtained a sample of the rare NE-Alpha and were testing it on a specimen, Lisa Trevor, when the parasite was mysteriously absorbed into her body. The parasite incubated in Lisa’ boy for a total of twenty one years before “evolving” into the G-virus. Birkin worked on it for a further ten years in the Raccoon City labs until he managed to successfully synthesise the first sample. The G-virus gives increased strength, speed and regenerative rates. The only way to do this is to increase the subject’s metabolic rate, which increases the rate at which cells divide. Unfortunately the body is not able to keep up and mistakes are made in the new cells’ DNA, similar to the effects of radiation sickness. Due to the incorporation of the virus’s RNA sequence this causes a cascade mutation effect, where violent mutations occur until the subject’s body breaks down. An infected subject will also search for hosts with similar genes to implant with G-Embryos. Infection causes subjects to become as strong as any Tyrant.