What we know so far: The Peacekeepers wanted a team of commandos to capture an
intelligent virus and bring it back to a Gammack base. Larraq led that team and was
destroyed, along with the virus, when he tangled with Moya. The Nebari have been secretly
spreading a dormant intelligent virus throughout the sector via sexual conduct. The ultimate
goal of this Nebari plan seems to be for them to gain control over all of the innocents who
have the Nebari virus.
Do we know why the PKs wanted the virus so badly? If I remember A Bug's Life correctly,
Larraq never told Aeryn when she asked (if she asked). I think the PKs, or at least someone
on that Gammack base (Scorpius?), knew EXACTLY what the Nebari were planning, and they
wanted to be ready. The only way they could do that would be to gain control of the same
virus the Nebari already gained control of, in it's wild form, and make sure IT (the PK version)
could nullify the effects of the Nebari version.