The t-Virus (also known as the Clay virus ε-strain and the tyrant virus[1]) is a mutagenic virus created by the Umbrella Corporation. It was derived from the Progenitor virus and designed to take advantage of its mutagenic properties for the development of a new form of biological weapon known as "B.O.W." (Bio Organic Weapon), a living creature genetically modified for use as a killing machine.


At one point near the end of the twentieth century, the Progenitor Virus (also known as the Mother Virus) was discovered by Lord Ozwell E. Spencer, Sir Edward Ashford, and James Marcus. These three gentlemen had a certain economic position and decided to begin research upon the virus. Most of the research was carried out by Marcus, as Ashford died in 1968 and Spencer was already occupied by his burgeoning chemical corporation, Umbrella. Marcus had little resources to pool into the investigation, until Spencer agreed to employ him as a researcher and later Director of his Corporation's Training Facility, putting the vast resources of Umbrella into his hands. Marcus overbid his hand, greedy for the power to finally invest serious amounts into his research, demanded numerous resources to perfect and improve what he envisioned was his life's work. This led to friction between Marcus and Spencer, who, to compensate from the crippling economic demands laid by Marcus, demanded that he create a virus with a 100% effectiveness rate, much to the confusion of Marcus and his assistants, new Umbrella Trainees Albert Wesker and William Birkin.

The Umbrella Corporation used its finances to secretly develop the virus under the radar of international authorities. In time, Marcus further evolved the virus, creating the first effective bioweapon to be produced in large quantity and be closely studied by the Umbrella Corporation. By adding the virus to leeches, the attributes of both were combined, and the t-virus soon saw the light circa 1978.

Though most of the research for the virus took place within the Arklay Laboratory under the Spencer Mansion in Raccoon City and the Umbrella Training Facility under Marcus' orders, covered by the American Umbrella offices, Spencer's Umbrella empire in Europe raced against Marcus to adequate the t-virus to create a virus with an even greater destructiveness. Marcus' dreams to overthrow Spencer and his attitude towards the virus as a "money-spinning tool" for Umbrella were never fulfilled, as he was murdered before he could enact them. Birkin came to be known within Umbrella circles as the true creator of the t-virus.

During those years, vast numbers of t-virus strains were developed in the Arklay Laboratory, and tested upon one solitary test subject: Lisa Trevor. For years, she was subject to intense biological torture, which, despite all odds, she survived.

As well, William Birkin, grown conceited as being credited as the creator of the t-virus, spawned a myriad of biological weapons to serve as backup to the virus, to ensure a 100% death ratio in any populace the virus should be released. Among these are the Hunters (created by fusion of a human fertilized egg with t-virus infected reptilian DNA), the Ivies (flowers grown to unnatural proportions and given animal instincts, locomotion and rudimentary defense mechanisms), the Chimeras (a mixture between a fly and human given vague humanoid appearance, increased size and mass, improved claws, and better reflexes), the Cerberus' (infected dogs), and most importantly, the crowning achievement of Birkin's career for the time: the Tyrants.

Later, Lisa Trevor's body, by now a melting pot of unthinkable disease, had deteriorated to inhuman levels. Noting she was, while not a Zombie, incredibly stronger, slightly more intelligent, and impervious to all damage, Birkin decided to test the Nemesis parasite (by then reputed to kill all its hosts, no matter how strong, in a matter of twenty minutes) in her. The results astounded even Birkin: Lisa's body, by then a hideous amalgam of all viruses ever tested on her, overcame the parasite and absorbed its rejuvenation properties, giving her even more destructive capabilities, greater strength, and total invulnerability to gunfire. Even with shackles she could not be bound, so after she outlived her capacity when Birkin extracted what would become the G-virus deep from her, he had her killed and disposed of.

When the time came, in early-1998, James Marcus revived, rejuvenated by the immense power of the first t-virus strains, coordinated into a steady pace by his own DNA and that of his leeches. For more than three decades, the t-virus threat had been averted, but at the time of his awakening, the Arklay woodland slowly was corrupted by the infectious agent. Before long, the Arklay laboratories had fallen; as the former Umbrella Training Facility was thought deserted, an Umbrella team (likely to be the U.B.C.S.) was dispatched to destroy the infection from there, before Marcus wiped out the entire platoon with his army of leeches.

From there, stories started stemming from the forest; several killings took place and an elite team of paramilitary units, 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. Rebecca in particular killed the reborn Marcus and his army, thereby shutting off a massive source of infection. All of them ended up holed up in the massive Spencer Estate and its adjacent areas, where later the S.T.A.R.S. Alpha Team entered as well, after suffering a similar fate at the hands of a pack of Cerberus'.

Later on, the remaining members of S.T.A.R.S. met up at the underground laboratory where the Tyrant T-002 was kept. This Tyrant killed, albeit temporarily, Albert Wesker, and was destroyed by a rocket blast in the second brawl it offered the remaining S.T.A.R.S..

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 shut down.

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

Yet another occurring on Sheena Island; an Umbrella owned Tyrant Factory. Hundreds of people from across the globe were kidnapped and taken there to be made into Tyrants. This infection was caused by the - now mad with power - Commander Vincent Goldman. The island was "sterilized."

A final outbreak occurred on an Umbrella-owned luxury cruiser, the Spencer Rain caused by an ex-Umbrella terrorist. All crew and passengers were transformed into T-G Zombies with the new cross virus, the tG virus which was formed with the merge of "t" and "G". The ship was destroyed.

No matter how many outbreaks have been produced by it, the t-virus remains a constant threat to global safety.


Effects of Infection[]

The t-virus is built like many viruses, but not all. As the cell 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.

The t-virus kills and replaces the dead mitochondrial organelles with a replica of itself. The virus then combines with other cells to produce energy. The energy produced is just enough to power the motor neurons and the basic lower brain functions. Not only that, but this bypasses the entire circulatory system, which makes the heart and lungs redundant systems that can be disposed of. The reanimated host body is then left with the intense need to feed in order to replenish energy supplies without having to sacrifice its own tissue. Actions taken by the host in this time period greatly resemble that of "zombies" depicted in horror movies, and are thus dubbed by that name.

However, the t-virus can only properly function by consuming the cell in order to produce its energy and to divide via mitosis to spread around the body. 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 telencephalon, better known as the cerebrum, to govern behavior, resulting in the infected host to exhibit primitive animalistic behavior. 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 as a V-ACT, commonly referred to 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.

If by chance a human t-virus host should survive past the secondary Crimson Head mutation with little or no damage, the virus may actually strengthen the damaged/remaining cells, resulting in a Licker, a Crimson Head mutation taken to an extreme. The closest piece of evidence of this possibility would be the Regis Licker or "Suspended" that is encountered in Raccoon City's Apple Inn; as the specimen seemed to be going through the stages of mutation resulting in the change from a Crimson Head to a Licker. This is evident due to the "licking" and hanging abilities present in both Suspen-Dead and Lickers, but also the layer of skin still attached along with the majority of human physical traits. In regular Lickers, the host possesses a long, powerful tongue, from which it derives its name, and enormous claws. The skin has all but disappeared, revealing the underlying muscle, and the brain is exposed. It is not known though how much more mutation can actually occur past the form of Lickers, as all known untampered specimens were destroyed in the destruction of Raccoon City.

In Resident Evil: Umbrella Chronicles Wesker states in a file that he sees 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 mutations, 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.

This theory fits in with the introduction of one of the steroids necessary for the creation of the mass-produced Tyrant, the Beta Hetero Nonserotonin, and it could signify the virus manifests itself in different forms depending upon the presence or absence of certain hormones in the human brain. Following this thread, it is not a ridiculous assumption to believe either certain viruses are better at producing certain types of mutations depending upon said hormones.

Means of Infection[]

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. This description has very little (if any) difference from the true writer's intent. 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.


One of the theories for the initial outbreak at the Arklay Research Facility is that the scientists and researchers there were infected once the t-virus contaminated the water supply. However, this theory is practically confirmed to be false because Dr. Marcus admitted he was the one who released the t-virus at the Spencer Mansion, in addition to contaminating the Umbrella-owned train, the Ecliptic Express. However, the virus can be transmitted by water, as proved when rats which had consumed samples of the t-virus infected water supply of Raccoon City caused the historical zombie epidemic.


Though there are discrepancies between canonical and non-canonical material over whether or not the t-virus is an airborne virus, when the virus broke out in the Arklay Research Facility the cleanup workers wore bio-chemical protection suits. This is the main argument for those who feel that the virus is an airborne pathogen, if only for a short period of time. However, the use of hazmat protective suits does not prove that the virus is airborne, but only that the workers were cautious in protecting themselves, perhaps from accidental contact with the virus (ie. touch). Throughout the Resident Evil titles, only the non-canon live-action movies have shown it to be Airborne, yet only in the first movie, with the second and third showing it only passing through direct contact (see under).

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. The 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.

T-virus History in The Movies[]

"Warning: Non-Canon Material"

The "T-virus" was developed by Dr. Charles Ashford in order to reverse the inevitable cellular breakdown in his daughter Angela Ashford. The virus acts by stimulating pre and post-mortem cellular growth, with the unfortunate side effect of basically killing the host in the process. To counter this, Ashford developed an anti-virus. When the T-virus was used, and kept in check by the anti-virus, Angela Ashford could avoid the debilitation that had kept her father confined to a wheelchair.

The effects of the virus in the movies do not differ widely from the game virus. There are a few exceptions:

The rate of infection varies, but is generally much shorter than the games, depending on the severity of an infected person's wounds. In the movies, a severely injured Rain lasts less than two and a half hours, while Carlos Oliveira goes for more than three before showing any outward signs of infection. In both cases, the subject lasts longer in the games. Bio-weapons like the licker are produced differently in the movies. A licker is created by direct injection. Similarly, a scratch from a licker can cause mutation. A stronger strain of the T-virus also exists, accidentally created by Sam Isaacs when he treated zombies with a serum derived from the blood of the Alice clones. The resulting "Enhanced Zombie" carried a much stronger viral load; once bitten, even multiple doses of the anti-virus could not remove the infection.

Known Antigens[]

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.

The first is an unnamed vaccine developed by Douglas Rover of the Umbrella Medical Service at Raccoon General Hospital (depicted in Resident Evil 3: Nemesis) 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 Nicholai Ginovaef or destroyed after Nicholai used C-4 explosives 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 vaccine for Jill Valentine (who had been infected by the t-virus) and manage to escape moments before the hospital's destruction.

The second serum is Daylight (depicted in Resident Evil Outbreak), developed by Greg Muller and Peter Jenkins of the Raccoon University. The actual ingredients for Daylight are T-Blood (a blood sample of a t-virus infected creature, namely Thanatos), V-Poison (a sample of poison from an infected Wasp) and 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.

The third is a reagent designated "AT1521," developed by the research team operating from within Umbrella's official Raccoon City facility. Surviving members of the team (including Linda and Carter) return to the facility in order to retrieve the serum for full-scale production of a cure to help prevent the spread of the t-virus in Resident Evil Outbreak File #2. It has similar features to the Daylight serum; and it was suggested that it was a prototype or, as Carter states, a 'sample'. 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 T-0400TP not long after its initial appearance). However, Linda did remember the raegents base, and thus was able to remake a sample.

There are also some prototype antibodies for the t-virus used by the U.B.C.S.. They were only mentioned by in a pocketbook kept by a deceased ubcs mercenary in the St. Michael Clock Tower.

There is one seen only within the movie world, called Anti-Virus, is a dedicated, engineered antivirus created by Umbrella. This one is only effective if the patient does not have a large amount of the t-virus in their bodies, or the infection is caught in the early stages. This one was shown in the first and second movie but its effects were different and it was developed by Dr. Charles Ashford for his daughter, Angela.