"This is the t-Abyss virus, and we are equipped to infect one fifth of the earth's waters.
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.
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, Raymond Vester visits 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.
These are the list of known mutations that were brought about by the t-Abyss virus: