Quote from FuzionReaktor
The novel (or maybe the anime too to some extent, not sure) actually explains that the Crusnik nanomachines are a special type of 'alien' nanomachine encountered by the Mars colonization project which fed on the infected cells of the Methuselah virus (which was also found by them). Abel and the other Crusniks, being modified and supposedly perfect humans, were able to take them while everyone else died upon being injected with them. Instead, the modified humans became Crusnik and the normal ones were infected and became the first Methuselah with the Crusniks basically being totally immortal in age whereas the Methuselah are simply very physically fit humans who's immune system and general body are improved to such an extent that they can live far longer than normal humans. Which were oppressed on their return to Earth and thus the war, etc. With Abel being the leader of them and attempting to wipe out humanity. etc etc etc: Begin current TB timeline.
been a long time since i watched the anime, but wasn't the nanomachines and vampires made by humans before the great war? created with stronger bodies for colonization of planets with harsh environment... at least the krusniks were, i remember abel explaining that