(Capcom's primary storyline)
The t+G Virus is a species of retrovirus descended from Progenitor Virus. It was engineered by Umbrella Europe at some point between 1998-2002, with work ceasing following a raid on the Paris Laboratory.
The origins of t+G are rooted in the events of 1998, when Umbrella HQ ordered the confiscation of Golgotha Virus research from NEST, to be handed over to Dr. Christine Henry at the Loire Laboratory. After acquiring the virus, an Epsilon strain was exposed to anti-G antibodies to induce selection, resulting in an enhanced t-Virus emerging. Research conducted on this new virus went through several stages as Umbrella attempted to create a more effective viral weapon. One variant, "Ver.0.9.1." was considered to be a failure due to its inability to grant a Tyrant test-subject bioelectric abilities that the virus was theorised to enable. A later virus, dubbed "Ver.0.9.2.", was seen as a possible success though it had not yet been tested on a human subject when it was stolen by bioterrorist Morpheus D. Duvall in September 2002.
Properties and mutations
The nature of the virus caused the host to gain defensive electrical properties, amplifying the body's electromagnetic field so that it developed a high voltage, allowing it to repel most projectiles. It also increased the host's strength and speed and allowed the host to retain full intelligence, like the t-Veronica virus, due to the fact that it does not damage the brain or diminish higher brain functions.
An early agent of the virus known as "V.0.9.1." was administered to a test subject, which was named "Tyrant 091". This Tyrant was deemed a failure, as it failed to produce bio-electrical properties and had very low intelligence. A newer agent known as "V.0.9.2." was stolen by former Umbrella employee Morpheus D. Duvall, who later administered it to himself, resulting in full adaptation with the aforementioned bio-electrical properties and no loss of intelligence, unlike Tyrant 091.
The "Charged Particle Rifle" was the only known weapon able to damage an organism infected with the t+G Virus. It was developed at the Atlantic Waste Disposal Facility by followers of Morpheus, and was later used by Bruce McGivern to pierce Morpheus' electromagnetic field after he had injected himself with the virus. After sustaining enough damage, the genetic structure of the fused virus broke down, allowing the G-Virus to begin mutating at an alarming rate, causing Morpheus to become a giant, unrecognizable blob of flesh and empty mass.