Mainstream universe
(Capcom's primary storyline)

"t" virions through a microscope.

Tyrant Virus, commonly abbreviated as "t-Virus", is the name given to a series of strains of the Progenitor Virus that were engineered by the Umbrella Corporation in the 1970s and 1980s. With the exception of a variant created by Alexia Ashford, the t-Virus variants were created primarily for military uses due to their ability to trigger violent genetic mutations in the infected.


Initial development Edit

From the Progenitor Virus' discovery in December 1966, the ultimate goal of Dr. Lord Oswell E. Spencer and his colleagues Dr. Lord Edward Ashford and Dr. James Marcus was birthing a new age of eugenics with mutagenic viruses improving the human race. To fund this program, dubbed the Wesker Project, it was agreed that strains of the virus should be engineered as a military product, leading to the creation of Umbrella Pharmaceuticals as a front for this research. Research on these virus strains, dubbed "t-Virus", was conducted simultaneously in a number of laboratories.

Dr. James Marcus' research yielded one such "t-Virus" in 1978 when he identified a mutant strain of Progenitor Virus in leech test subjects which led to violent, cannibalistic impulses, loss of intelligence and necrosis.[1] This represented a significant advancement in viral weapons research, as the natural Progenitor Virus strains of Africa almost always killed infected humans.

The nearby Arklay Laboratory was also working on their own t-Virus research under much stricter influence from Lord Spencer. This team had already created "Zombies" around the same time as Dr. Marcus by bonding their own t-Virus with the genome of the Ebola virus. Spencer was, however, unsatisfied with the virus the Arklay team was developing, as approximately 10% of people were believed to be naturally immune to it. To guarantee a near 100% success rate in battle, the Arklay team bonded a human egg and reptilian DNA through the virus in 1981, creating the "Hunter", a creature that would be used in battle to kill these remaining survivors.[2] Its lead researcher, Dr. William Birkin, was referred to as the "creator" of the t-Virus after Dr. Marcus' assassination in 1988.[3][4]

A third group researching the t-Virus development was located in Antarctica, led by Dr. Lord Edward Ashford and his son, Alexander. As Alexander was not a trained virologist, he was unable to lead the project after his father's sudden death, and research was effectively halted there for over a decade until the genetically-engineered Alexia Ashford developed a new t-Virus by infecting a queen ant with the Progenitor Virus, the queen itself already being infected with an ancient virus endemic to ants. Alexia went into hiding soon after infecting herself with the virus, and it was believed until fifteen years later that her experiments had failed.

Use on the black market Edit

In 1998, a series of biohazard outbreaks involving the t-Virus began to occur. Several outbreaks were caused in the Arklay Mountains region due to the machinations of the Queen Leech, which had bonded with the DNA of James Marcus and became a veritable clone of the former scientist. For more than three decades, the t-Virus threat had been averted, but at the time of his awakening, the Arklay woodland was slowly corrupted by the infectious agent. Before long, the Arklay laboratories had fallen. The Laboratory was seemingly infected by infected water, causing its employees to fall to anarchy over the relatively long period of time between May 11[5] and late June, 1998.

From there, stories started stemming from the forest; several killings took place and an advance party of an elite paramilitary unit -, the S.T.A.R.S. Bravo team - was sent from Raccoon City to destroy the threat, oblivious to its real cause. Only four of these members, Rebecca Chambers, Enrico Marini, Kenneth J. Sullivan, and Richard Aiken survived the night. All of them had holed up in the massive mansion and its adjacent areas. The next evening, the S.T.A.R.S. Alpha team sought refuge in the mansion as well, after losing a man to an attack by the multitude of cerberuses, mutated Dobermans, which infested the grounds.

Later on, the remaining members of S.T.A.R.S. met up at the underground laboratory where the Tyrant (T-002 Type) was kept. This Tyrant killed Albert Wesker temporarily, and was killed by a rocket blast in a skirmish with the remaining S.T.A.R.S as it attempted to foil their rescue by returning Alpha team pilot Brad Vickers.

After the demolition of the manor, the virus sources were thought stopped definitively, but when William Birkin's subterranean laboratories were attacked by Umbrella's Black Ops in September 1998 in an effort to retrieve his G-virus, another outbreak ensued. This infection encompassed all of Raccoon and ended in the forced termination of the entire city. Umbrella was immediately exposed as creator of the virus due to the enormous amount of evidence produced from the scarce survivors, and was systematically dismantled and shut down.

Still, another outbreak was induced in late 1998, on Rock Fort Island, this time by the revived Albert Wesker and his new employers, referred to only as the Organization. This ended in the partial demolition of the Umbrella installations there and the total destruction of the South Pole Umbrella Research Center.

Yet another occurred in 1998, this time on Sheena Island; an Umbrella-owned "Tyrant Plant". Hundreds of adolescents from across the globe were kidnapped and taken there to be dissected, to retrieve a hormone important for the psychological development of the Hypnos-T Type.[6] This infection was caused by the - now mad with power - commander Vincent Goldman. The island was "sterilized" when facility's self-destruct system was activated.

Another occurred in 2002 on an Umbrella-owned luxury liner, the Spencer Rain, which was caused by an ex-Umbrella researcher-turned bio-terrorist named Morpheus D. Duvall, who was fired after the company used him as a scapegoat for the disaster at the Arklay facility.[7][8] The ship's crew and its passengers were transformed into zombies, or were killed by the B.O.W. specimens prepared for auction and display purposes. The liner was destroyed when it crashed into an island which housed the -also infested- Umbrella Waste Disposal Facility.

Also in 2002, an Amazonian organ-trafficking crime syndicate got hold of "t" and the similarly named, but otherwise unrelated, "t-Veronica virus". Receiving "t" and B.O.W.s through a dummy company of the Russian branch of Umbrella, the syndicate's leader, Javier Hidalgo, armed his organization with biological weapons. He also purchased t-Veronica through Albert Wesker, and proceeded to use it to treat his daughter from the same illness as her mother. After his daughter ran off, Javier, in a fit of rage, released the t-Virus throughout the surrounding area. The virus spread to at least two villages, transforming their inhabitants into zombies. Leon S. Kennedy and Jack Krauser ended Javier's rule with the assistance of his daughter.

A bioterrorist attack in 2005 India was halted by WilPharma Corporation's t-vaccine. This attack was actually planned by a WilPharma Corporation researcher, who wanted to demonstrate power of the virus and its vaccine to potential buyers on the black market.

Another outbreak occurred in 2005, within the Harvardville Airport, where the infection began after a single zombie entered the building and began to attack people within the building. A small-scale outbreak happened at the nearby WilPharma Corporation bio-dome facility, after a bomb was detonated. Both facilities were eventually sterilized, however.

The last known outbreak occurred in 2010, in Philosophy University, Australia where Rebecca Chambers was teaching as a guest lecturer. The BSAA forces stopped the outbreak from spreading further.

Then sometime after the Raccoon City outbreak a series of bioterrorist attacks started happening all over the world and so far the virus used in said attacks was the t-virus.

Development timelineEdit

  • September 19, 1977: Dr. Marcus' project on altering Progenitor reaches a breakthrough, and he coins the variant "t-Virus".[9]
  • February 3, 1978: Marcus begins his experiment on leeches by infecting them with the modified Progenitor virus.[10]
  • July 31, 1978: t-Virus research begins in the Arklay Laboratory. Led by Dr. Birkin, the team intends to merge the genomes of Progenitor and Ebola to create a military weapon that would kill entire enemy populations.
  • October 23, 1978: Marcus ceases experimenting on rodents, citing humans as being the perfect guinea pig to prove its abilities.[9]
  • January 13, 1979: Marcus ends his research with the Leeches.[9]
  • January-February, 1979: Spencer has employees steal Marcus' research.[9]
  • 1981: The Aklay team begins creating B.O.W.s as a means of killing the 10% of people found to be immune to their Progenitor-Ebola "t" strain.
  • 1988: Marcus is assassinated and credit for the virus' creation goes to his student William Birkin, who was a conspirator.[11]
  • 1993: An experimental oncolytic virus treatment based on the t-virus, designated "T-JCCC203", is used in illegal medical experiment trials.
  • 2002: A hybrid strain of the t-virus and G-virus is created. The virus is named "t+G".


Effects of InfectionEdit

The t-Virus is built like many viruses, as the virus makes contact with a cell's membrane, it inserts its genetic coding into the cell. The cell absorbs the viral genome into its own genetic make-up, which takes over the cell's functions. The cell begins to produce offspring of the original virus. The new viruses are then released from the host cell and infect the neighbouring cells, which starts the process all over again.[12]

The t-Virus can only properly function by consuming the cell in order to produce its energy. This slow breakdown of cells leads to the gradual breakdown of the host, causing necrosis. The virus incorporates itself into the host's DNA, which substantially alters it. This is why creatures, such as bees and spiders, only have very minor mutation, such as increased size, when compared to the human mutation caused by the virus.

Should the human host be alive at the time of t-Virus infection, all higher brain functions are destroyed. This leaves only the brainstem to govern behaviour. This leaves the infected host with a very animalistic behaviour. As the virus spreads, it damages the hypothalamus. This produces a massive flood of neurotransmitters, enzymes, and hormones such as norepinephrine and dopamine. These effects, combined with the painful symptoms of the infection, induce a psychotic rage, persistent hunger, and increased aggressiveness in those infected.

Should the human host be dead at the time of infection, only enough energy is produced to power the lower brain functions. These functions are responsible for the most primal instincts, such as walking and eating.

In either case, their late-stage appearance and behaviour are characteristics of their name-sake, a zombie.

Should a late-stage human host be rendered unconscious, the body will lay in a dormant phase appearing to be dead. In actuality the host is rapidly mutating due to the t-Virus becoming hyperactive. Within the time frame of an hour, the decayed skeletal and muscular system is reconstructed into a stronger and more durable form. Development can be seen of sharp canine teeth and razor claws, fresh blood seeps into remaining skin giving it a reddish hue, advances in decomposition, and intact eyes become a bright white. Umbrella researchers at the Arklay Laboratory have dubbed this stage "V-ACT", referring to the resulting creature also known as a "Crimson Head". To awaken, the brain must be jolted back to consciousness with a slight but important increase in intelligence, and large increase in agility and aggressiveness. As a consequence of this rapid mutation, cellular breakdown hits a critical point where the host cannot regenerate properly and can be killed permanently.

Depending upon the strain, the V-ACT may have different results. In the strain released in Raccoon City, most V-Acts usually resulted in creatures named by RPD staff as "Lickers". Which are completely blind and use their hearing to detect prey. At which point, they use their long tongues to strangle, impale, or decapitate their prey. At close quarters they also have sharp claws to slash their prey. Lickers may eventually evolve into a more advanced stage with larger claws. Lickers have exposed brains which serve as a weak point.

An oddity of V-ACT is a creature known as "Suspended". Only one specimen of this creature is known to exist. What it actually is, is unknown. It could be an in-between stage of a zombie and Licker or some kind of rare mutation V-ACT takes on. If it is a zombie partially evolved into a Licker, it would account for why its unable to spear prey with its tongue. It's only capable of grabbing its prey and using its tongue as a whip.

There are rare cases where a human genome can stably splice with the T-Virus's genetic material. The probability of an average human having this reaction, when exposed to the T-Virus, is approximately one in ten million. The result is a humanoid creature called a Tyrant. These creatures inherit all the enhancements of the Tyrant Virus, while lacking most of the degenerative weaknesses that result in zombies. They posses enhanced skeletal-muscular frames and superhuman strength, speed, agility, and durability, while still retaining enough intelligence to follow orders and carry out missions, making Tyrant's effective B.O.W.s. However, if a Tyrant's biological functions become unstable, it can undergo a secondary metamorphosis into a Super Tyrant. This transformation is analogous to V-Act in zombies, that results in Crimson Heads and Lickers. The subjects undergo greater bone, muscle, and cardiovascular growth and may develop features such as claws and an exposed heart. Super Tyrants are significantly harder to control, so this transformation is not preferred. To act as a failsafe, many of the mass-produced Tyrants are equipped with a Power Limiter, a device that stabilizes its biological functions and prevent the creature from accidentally becoming a Super Tyrant. If the device is destroyed however, nothing will stop the transformation from happening.

Wesker notes that he observes similarities in the apparently random mutations endowed by the virus (as examples he mentions the mutations undergone by Sergei Vladimir and what he knew of James Marcus' mutations) and explains he believes that the host's mindset is a crucial factor in explaining the mutation (e.g.; Vladimir becomes what Wesker calls "a monster whose very body is the picture of suffering", revealing what Wesker considered to be Vladimir's true self, and the rejuvenation experienced by Marcus, an aged man who understandably desired control and the restoration of his vibrant youth, characteristics that were carried to his own eventual mutation, including his true madness and the horrific mutation that overcame him in the end), and briefly wonders where does this theory fit with his own mutations.

Means of infectionEdit

The t-Virus is capable of various methods of subject infection. Research files supplied in the Arklay Mountains facility identify the virus as having a protein structure. As such, it is likely that any known methods of viral of Umbrella's experimentation (known as Bio Organic Weapons) with the t-Virus were initiated by direct injection of the virus into the host. This was considered Umbrella’s primary means of infection.

  • Water: In the initial outbreak at the Arklay Laboratory, the above-ground scientists and researchers were infected once the t-Virus contaminated the water supply. Similarly, Arklay Dam and the Raccoon Sewage Treatment Plant were also contaminated with the virus, leaking into the city's water supply as a result and infecting many civilians.
  • Air: The t-virus in its original form is an airborne virus, but upon infection of an organism, it mutates into a form spread via skin and fluid contact.
  • Direct Fluidic Transmission: Anyone attacked by an infected host in close combat, be it by bite, scratch, gash, or stab will have the virus transferred to their bloodstream via contact with infected bodily fluids and tissues. Umbrella Corp. believes this to be a secondary means of infection. For story purposes, however, most of the main characters in the games were never canonically bitten or stabbed, though even highly infectious real world viruses do not always infect the victim after one exposure (but given the relentless attacks of those infected, one exposure might not necessarily mean a single scratch or bite). A "Dry Bite" is possible as well, so anyone bitten has at least a 1% chance of not getting infected. Evidence for this can be seen when an Eliminator bites Rebecca Chambers during a cutscene in Resident Evil 0.

Known TreatmentsEdit

There are four known serums that will cure those infected by the t-Virus, but only in its earlier stages, before it becomes completely active.

Raccoon General Hospital vaccineEdit

The first is an unnamed vaccine developed by doctors at Raccoon General Hospital[13] as a last-minute effort to halt the rapid spread of the t-Virus. However, most of the hospital's staff had already succumbed to infection before the vaccine could be properly produced even in small amounts.

This vaccine could be cultivated by using a specialized synthesizer and inserting a medium base into the system, then combining the necessary chemicals using the control panel. The exact components that were used to create this prototype are unknown; as most of the documentation regarding its production were either stolen by Nikolai Zinoviev or destroyed after Nikolai used C-4 to demolish the hospital, taking with it any evidence of the Umbrella Corporation's involvement with the hospital in the process.

However, Carlos Oliveira was able to create a single dose of the vaccine for Jill Valentine and managed to escape moments before the hospital's destruction.[14] While the vaccine apparently did not immediately cure Jill of the virus, it did send it into hibernation, until it eventually died out. It also apparently created powerful anti-bodies within Jill, making her immune to most other viruses, even possibly Uroboros, another virus strain extracted from the Progenitor Virus.


Daylight was developed by Greg Mueller and Peter Jenkins of the Raccoon University.[15] The actual ingredients for Daylight are:

  • P-Base - an unknown chemical liquid that requires preparing before being mixed. Once all the ingredients have been collected, they can be mixed together in a special chemical mixer. The mixture takes about five to seven minutes to make and thirty seconds to one minute to duplicate.


"AT1521" was developed by the research team operating from within Umbrella's official Raccoon City facility. Linda and Carter, surviving developers of the vaccine returned to the facility on October 1, 1998 to retrieve it in hopes of widespread production of the vaccine.[16]

The exact details of the serum itself are unknown due to the short role it played in the storyline (the sample being destroyed by the rampaging Tyrant R not long after its initial appearance). However, Linda did remember the reagent's base, and thus was able to remake a sample.


The fourth is an anti-"t" agent known as the t-vaccine created by WilPharma Corporation. Unfortunately, most of the samples were destroyed by Frederic Downing right after the Harvardville Airport t-Virus outbreak, and the last t-vaccine sample was taken by Downing so that he could sell it to bioterrorist general Miguel Grandé along with the t- and G-virus samples, but he was caught by Claire Redfield and Leon S. Kennedy before he could sell it.[17] It is possible that the US Government used this last anti-virus sample to produce more in case of future outbreaks.


There are also some prototype antibodies for the t-Virus used by the UBCS. They were only mentioned by in a pocketbook kept by a deceased UBCS mercenary in the St. Michael Clock Tower.[18] It should be noted that no "zombified" UBCS members were encountered in the Clock Tower. But they also notes that the virus had already mutated and already neutralized the Antibodies effects.

Regular Anti-viral pills can slow down t-Virus mitosis temporarily.[19]

Further notesEdit

  • As the "t" and Uroboros viruses are variants of Progenitor, it can be deduced that for someone to co-exist with either of the three viruses, they must have specific genes that vary between them. This trait is incredibly rare, and that only 30 people statistically have it in the United States - with a population of 300,000,000. This 1 in 10 million chance of having this trait means that Tyrant development is kept short of suitable candidates. This was the reason why Umbrella sought to clone Sergei, a carrier of this gene.
  • In the video games, the t-Virus is green in colour, but is blue in the films, while the green canisters are speculated to be the antidote.
  • In Resident Evil Zero and Resident Evil Survivor the t-Virus (along with its parent virus in Resident Evil 5) is visible under microscope. It should be noted that virions are generally not large enough for the naked eye to see with a standard light microscope, though some viruses are known to be larger than certain bacteria species.
  • In Resident Evil 2, the color of the T-virus is green while in Operation Raccoon City, the color of the virus is blue.
    • In the first film of Resident Evil, the color of the T-virus is cyan instead of green but in a zig-zag design and the latter antivirus is lime green.
  • According to Luis Sera, a t-Virus sample was being held at the Madrid Police Department in 2004.
  • Several viruses created later were based on the t-virus, including the G-Virus, T-Veronica virus, Uroboros virus, T-Phobos Virus and the C-Virus which was a combination of an enhanced veronica virus and the G-virus.



  1. Resident Evil 5 (2009), file: "History of RESIDENT EVIL"
  2. Wesker's Report II.
  3. Resident Evil 2 - Annette Birkin refers to William as "The man who created the t-Virus"
  4. Resident Evil 0 - William walks to a dying Marcus and tells him he will "take over" his research
  5. Capcom. Resident Evil. (Capcom Co., Ltd.). File: Keeper's Diary.
  6. Resident Evil Survivor (2000), file: "How to extract Beta Hetero Nonserotonin"
  7. Capcom. Resident Evil: Dead Aim. (Capcom Co., Ltd.). File: Emergency FAX from Paris Branch.
  8. Capcom. Resident Evil: Dead Aim. (Capcom Co., Ltd.). File: Reconstructuring Notice.
  9. 9.0 9.1 9.2 9.3 Resident Evil Zero (2003), file: "Marcus' Diary 1"
  10. Resident Evil Zero (2003), file: "Leech Growth Records"
  11. Resident Evil Zero (2009), scene: "Confrontation With Marcus"
  12. Wikipedia: Viral Replication at Wikipedia
  13. Resident Evil 3: Nemesis
  14. Resident Evil 3: Nemesis (1999), scene: "Hospital Scene"
  15. Resident Evil Outbreak
  16. Resident Evil Outbreak File 2, "end of the road"
  17. Resident Evil: Degeneration
  18. Resident Evil 3: Nemesis (1999), file: "Merc's Pocketbook"
  19. Resident Evil Outbreak (2003), item: "Anti-Virus (L)"

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