(Capcom's primary storyline)
The t-Veronica Virus, is a strain of Progenitor virus created by Dr. Alexia Ashford which, under the correct conditions, allows the host to retain full intellectual capabilities. It is named after Veronica Ashford, the Ashford family's matriarch.
The basis of t-Veronica research came with the discovery of a retrovirus existing within the genome of some ant queens. Alexia mistook the eusocial nature of an ant colony for one with complete adoration for their "queen", and likened it to her own megalomaniac lifestyle personality. She then began considering the possibility of merging the genome of this virus with that of the Progenitor virus. Plant genes were also added into the virus's makeup.
The first step in human testing came in 1982, when Alexia and Alfred infected their "father", Alexander Ashford, with the virus. Due to not having a preparation beforehand, he failed as an adequate experiment; he was imprisoned within the Antarctic Base, terrifying the facility's workers with his inhuman growls, earning him the name "Nosferatu". Soon after her father's degenerative mutation, she christened the virus "t-Veronica", in name of her cell-donor.
It was soon after this that Alexia decided to experiment on herself. In order to prevent the degeneration Alexander faced, Alexia concluded that going into a cryogenic coma for fifteen years should allow her to adapt to the virus.
At one point this year, Albert Wesker intercepted a rumor regarding the existence of this virus. Expecting it to be somewhere in Alfred's Rockfort Island base, he and the H.C.F. attacked the island, leading to a biological outbreak of the t-Virus. Eventually, it was discovered by Wesker that Alexia was, in fact, alive at the Antarctic Base; he concluded, rightly, that he would find the virus there. He left via a submarine on his way to the base, situated in the Ross Ice Shelf.
Shortly after Alexia's revival, she proceeded to experiment on Steve Burnside. While he didn't have the benefit of a fifteen-year period of hibernation, Steve managed to counter the virus not long into his mutations, as he regained his sanity - he died soon due to his injuries. Later on, Alexia used the strain of the virus in her body to mutate into a powerful being during her battle against Albert Wesker.
Alexia herself mutated further into a queen ant monster and was killed by Chris Redfield with the experimental "Linear Launcher". With nothing surviving the ensuing destabilization and explosion of her body, the capture force instead took Steve's body for experimentation.
In order to impress Derek C. Simmons, Carla Radames acquired a sample of the t-Veronica virus and began experimenting with it in hopes of making a "perfect virus", despite her first thought that t-Veronica was an "obsolescent". By removing the genetic code of the virus which created sudden mutations and combining it with parts of the Progenitor virus, Carla developed a new variant of the t-Veronica virus: "T-02".
Unlike t-Veronica, T-02 did not degenerate its hosts' mental faculties, removing the need for lengthy incubation periods (as with Alexia) or constant organ transplants (as Javier would do for Manuela) to keep the virus stable. This greatly increased the potency of the virus, as well as its viability as a bio-weapon.
Carla later combined T-02 with the G-Virus variant found in Sherry Birkin's body. The resulting pathogen - the C-Virus - combined the greatest elements of t-Veronica and G, transforming its victims into intelligent, extremely dangerous creatures.
South America 2002
South American drug lord Javier Hidalgo eventually ceased purchasing B.O.W.s from the Umbrella Corporation, who had desperately begun to inflate their bio-weapons prices due to the Raccoon Trials. The t-Virus variant he had infected his wife, Hilda, with to treat her illness had begun to backfire. Hilda unfortunately transformed her into a grotesque aquatic creature.
When his daughter, Manuela, became ill, it was at this point that Wesker began doing business with him, selling him samples of t-Veronica at a much more reasonable price. Javier injected the virus into her while searching for ways to prevent the same degeneration that had taken Hilda. Javier later came to the conclusion that a means of countering the virus' control over the body was to constantly replace the infected tissue until the body was able to safely assimilate the virus. Thus, Javier arranged for Manuela to undergo a series of organ transplants for the next fifteen years - this way, she would remain in control of her body and continue to live a normal life with her father. To facilitate this grand plan, Javier's crime syndicate, the Sacred Snakes, began kidnapping young women of Manuela's age to be used in forced organ donation.
When US Government agent Leon S. Kennedy and USSOCOM member Jack Krauser began investigating the region in search for the Umbrella researcher who had been selling bio-weapons to Javier, they discovered Manuela. Being led to Javier's mansion, they discovered the organ donors and Hilda. Soon after, Javier infected himself with the virus by merging with the V-Complex in order to kill Leon and Krauser. Later on, Manuela realized the psychological aspect of t-Veronica: if she gave in, she would no longer feel pain; if she resisted, she would die human. She chose to die human in order to save Leon, throwing her combustible blood at Javier until he eventually died. Although weakened from blood loss, she nonetheless survived as an ordinary human.
The t-Veronica virus was not distributed on a wide scale like other viruses and parasites in the series, but it appears to operate similarly to its predecessors, the Progenitor Virus and the t-Virus. Notable differences include a tendency for infected individuals to manifest arthropod traits in their mutations, such as hard carapaces or insectoid limbs. The blood of a t-Veronica host often changes into a chemical that spontaneously combusts on contact with oxygen, allowing the host to weaponize their own blood as a projectile.
Like the t-Virus, the t-Veronica virus has a tendency to cause severe mental degradation in its hosts. Unlike the t-Virus, successful fusion with the t-Veronica virus does not require the presence of certain genes or hormones in its host - instead, the stabilizing factor appears to be the rate at which the virus is allowed to spread within the body. In order to perfectly co-exist with the t-Veronica virus, the host must live with it for a number of years, allowing the virus to adapt to their body. Alexia Ashford achieved this by entering a state of cryogenic stasis, causing the virus' infection rate to slow to a crawl, while Javier Hidalgo planned to regularly replace Manuela's infected organs with fresh transplants (thereby retarding the virus' spread by forcing it to constantly "re-infect" her organs). As with many variants of the Progenitor virus, the mutations induced by the t-Veronica virus are largely dependent on the mindset of its host.
Notably, two people infected by t-Veronica (Manuela and Steve) have been able to counter their mutations and regain control of their bodies through willpower alone. A more subtle example was Manuela's mother, Hilda, who regained some part of her humanity at the sight of Manuela and was kept at peace when she sang a lullaby that Hilda sang to her as a child. Unfortunately, when Manuela was too weak to sing the song, the monstrous personality regained control. Javier, like Alexia, was also able to control himself when mutated by the virus; however, due to him not having a preparation as Alexia did, he almost lost his consciousness. By the time Javier regained control over himself, he was only able to beg Leon and Krauser to kill him.
According to the V Complex's archive entry in The Darkside Chronicles, the virus' activeness was also dependent on the outside temperature. The frigid temperatures of the Antarctic meant that the virus could not travel as easily, and the virus could not infect its surroundings as easily. The tropical and humid climate of South America, however, caused the virus to reach ginormous proportions, potentially threatening entire ecosystems.
- Capcom Production Studio 4. Resident Evil - CODE: Veronica. (Capcom Co., Ltd.). File: Queen Ant Report.
- BSAA Remote Desktop, t-Veronica report
- Capcom. Resident Evil 5. (Capcom Co., Ltd.). File: History of RESIDENT EVIL.
- Capcom Production Studio 4. Resident Evil - CODE: Veronica. (Capcom Co., Ltd.). File: Alfred's Diary.
- Capcom Production Studio 4. Resident Evil - CODE: Veronica. (Capcom Co., Ltd.). File: Worker's Diary.