Uroboros Virus- Uroboros is an RNA virus in the Progenitor family. It was engineered in the 21st century by Dr. Albert Wesker as the ultimate eugenics tool. Later, a less potent strain was developed by Dr. Alex Wesker to serve as a bio-weapon. Currently, there is no known vaccine for either strain of Uroboros. The virus is named after the Ouroboros in Greek mythology, which is a snake or snake-like creature that consumed itself.
Work began on the Uroboros Project sometime in 2006, following an encounter Dr. Albert Wesker had with Oswell E. Spencer, Earl Spencer, who revealed to him Umbrella Pharmaceuticals' secret eugenics goal of creating a race of Übermensch to advance human society, with Wesker himself being part of such a project. Having begun to question the emerging War on Terror, he concluded that humanity itself was the problem, and the only way to bring about a utopian society of the Übermensch was to use the Progenitor Virus against the very planet itself, which would kill all but those with certain genetic characteristics. Such people would theoretically be enhanced physically and mentally.
The first setback took place after Tricell, Wesker's partner, set up a lab in the old Ndipaya Kingdom. The human population ratio able to survive and mutate from Progenitor infection was simply too small. Using t-Virus antibodies extracted from a mutant test subject, Jill Valentine, Wesker repeatedly used them on his Uroboros cultures to naturally select a new strain distinct and less potent than Progenitor. With a virus now useful in research, the project moved to its next stage and saw thousands of other test subjects infected over the next two years, with increasing assistance from Tricell's own research staff such as Miguel. The virus was more or less finalized by May 2008 when samples were loaded onto missiles in preparation for the final stage in the "Uroboros Project" - dispersing the virus across the Earth's atmosphere to infect every corner of the planet. There were problems with the preparations, however, and a fire occurred, resulting in the creation of a mutant arthropod species dubbed "Reaper". In March 2009, the project was finally underway, but was stopped by the Bioterrorism Security Assessment Alliance. At least four humans were infected with Uroboros during the operation, including Wesker himself. Only he mutated appropriately, however, with the other three being genetically incompatible. In their case, their bodies were torn apart by uncontrollable mutation, and in one case, consumed a number of other bodies.
Sometime after Albert Wesker's death, his compatriot Alex Wesker managed to obtain a sample of Uroboros. She took it to Sein Island, where bio-weapons research began shortly after the work on the t-Phobos Virus was completed. The injection of Uroboros into the corpses of failed t-Phobos test subjects resulted in the creation of the Revenant.
In 2011, Alex Wesker conspired with TerraSave leader Neil Fisher to provide Uroboros in exchange for more t-Phobos test subjects. However, Fisher was infected with the virus instead of being handed a sample, as punishment for betraying his friends.
Upon her own mutation from Uroboros and t-Phobos, Alex released her Revenants from the laboratories and let them loose across the island. Over the next six months, they slowly consumed every last food source, from corpses to wildlife. They were eventually eradicated by a BSAA team.
During the time when Barry Burton, Claire Redfield, and Moira Burton(Barry's daughter, who had been kidnapped) confronted a horrifically mutated Alex Wesker, and severely damaged her. She consumed large doses of Uroboros, augmenting her and making her enormous in size. At the end, Claire destroyed Alex by firing an RPG right into her exposed heart, ending her life, experiments, and reign of terror.
Comparable to the Progenitor virus, the Uroboros disease is noted to be almost always lethal in humans, with the exception of those with a particular genetic trait shared with the Ndipaya King. The disease goes through two stages, which can be defined as early and later symptomatic stages.
