yeah, Crusade.

So at the end of Babylon 5 there's a race that was allied with the Shadows called the Drakh. they used the last Shadow planet killer ship to attack earth which was defended by the ISA and two new ships that were joint Earth and Minbari projects (think really big White Stars) called Excalibur and Victory. they all defend the Earth but lose the Victory in the process. before the Drakh are defeated they release a virus into Earth's atmosphere that will activate and kill everything after 5 years. So the whole main plot for Crusade was to take the last Earth/Minbari ship, the Excalibur, and go out into the universe to find a cure within 5 years (JMS really likes his 5 year storylines). there's some side plots too like the psychic civil war on earth between Psi-Corp and random telepaths, Mars getting it's indipendence, and random other races finding Shadow tech.

It only lasted 13 episodes before getting cancelled and IMHO wasn't anywhere near as good as Babylon 5.