Ah, the Ultimate Pathogen. The pinnacle of pathological perfection.
It's genetic structure contains strands of DNA and RNA from every single known and unknown pathogen from the OMNIVERSE (which means every single known and unknown MULTIVERSE across every single known and unknown dimension), mainly the DNA and RNA from Experiments 069, 070, 093, and 999. It is a predator of Experiment 999. The DNA and RNA of Experiment 911 also contain strands of DNA and RNA from every experiment that has DNA and RNA.
What is it exactly?
It is a creature like no one has ever seen, a combination of every pathogen in all of existence mashed into one. The cells of this thing are infested with viruses and bacteria from every known and unknown universe, and is constantly mutating BY THE YOCTOSECOND. The mutations are so fast that the only thing in ALL OF EXISTENCE that can beat this, is of course, Experiment 1738.
Only one member of this pathogen exists, and this specimen is located in the same underground lab as the Death Virus's location.