T-Abyss

T-Abyss is a mutagenic virus from the Resident Evil franchise, featured prominently in Resident Evil Revelations. It was created by combining the T-virus with an oceanic viral organism.

Origins
The T-Abyss virus would be developed by a team of scientists at Montpellier University of Marine Science conducting deep-sea investigation at the Kermadec Trench with an unmanned exploration vessel. On their fourth expedition, reaching the Hadopelagic Zone, the scientists discovered a new virus in the body of a deep-sea fish, a virus that allowed the fish to survive in such great depth - they dubbed it the Abyss virus, after the fear of unfathomed depth. The T-Abyss virus was created by combining the Abyss virus with samples of the T-virus mutagen which had been developed by the Umbrella Corporation.

The creation of the T-Abyss virus demonstrated the ease of developing viruses that can mutate across species - mammals were just as susceptible to its effects as the fish that originally carried the Abyss virus. Although there were only a few incidents where the T-Abyss was used to attack, new types of B.O.W. were quickly developed with every use of the new pathogen.

In 2005, the terrorist group Il Veltro threatened to release the small quantity of the virus they possessed to contaminate 1/5th of the Earth's oceans.

After the events of Revelations, former FBC agent Raymond Vester visits his partner Jessica Sherawat in a cafe. He gives Jessica a vial of T-Abyss virus sample for her to bring to her employer, the TRICELL corporation. It is unknown what happened to the sample afterwards.

Effects
Because of the virus' corrosive nature, any organism infected by the T-Abyss will experience varying mutations, such as heavy physical deformity or losing body parts like lower jaw or fingers. Those infected by a stronger strain of T-Abyss will suffer horrific mutations to the point of being unrecognisable from their former self. The T-Abyss virus displays the ability to mutate any given organism, including those which were exposed to other viral agents.

Certain humans have genetic resistance to the virus. However, this does not guarantee immunity to the virus as they too mutated into B.O.W.s, notably the buzz-saw-handed Scagdead.

Mutations
Below is a list of all known mutations brought about by T-Abyss.

Irregular mutants

 * Ooze - Human carriers reduced to a zombie-like state; they are hideously deformed and their bodies take on a more amphibious nature. They are driven to feed on the bodily fluids of other creatures.
 * Sea Creeper - Female humans that have transformed into fish-like monstrosities that can only survive in water.
 * Scagdead - A rare human mutation where T-Abyss' spread is slowed by the natural resistance of the host. This does not stop the mutation process, however, and results in an even more grotesque transformation; a bloated, bulbous body with vestigial remnants of the host's original body and an arm that ends with an organic buzzsaw.
 * Ghiozzo - Arowana fish that rapidly transform into vicious mutants with mouths filled with razor-sharp fangs. They can survive out of water for a time, but are largely immobile on land.
 * Globster - Human infectees that experienced such severe mutation that their bodies have been transformed into featureless masses of flesh.
 * Malacoda - A group of parasitic worms fused with a whale that succumbed to secondary infection, creating an enormous tentacled creature.
 * Rachel Foley - An agent of the Federal Bioterrorism Committee who was killed and infected aboard the Queen Zenobia. She mutated into a unique form of Ooze, capable of moving much faster and was virtually immune to bullets. She maintained a degree of her former intelligence and the power of speech, but had been driven insane and homicidal by the virus.
 * Ultimate Abyss - The mutated form of Il Veltro ringleader Jack Norman after being injected with a massive dose of T-Abyss. His mutation resembled a semi-aquatic variant of the Tyrant-class bioweapon.

Bio-Organic Weapons

 * Draghignazzo - An absurd mutation combining both human and shellfish genes.
 * Fenrir - Wolves that have undergone severe cellular deterioration yet maintain their mobility and ferocity, just like the zombie dogs spawned by the T-virus.
 * Farfarello - A Hunter-class B.O.W. that has been enhanced by T-Abyss, gaining the ability to camouflage itself.
 * Scarmiglione - A B.O.W. created by combining the T-Abyss virus with both human and shark DNA.