There are currently five separate strains of the nanovirus: Brilliance 3.2 Glory 2.1 Splendor 2.6 Magnificence 2.0 Fortitude 3.1 Each one of these strains provides an XP boost, but they all provide different levels of the XP boost. It appears as though the virus spreads through Orbs of Light and being killed by an infected Guardian in the Crucible, and by being infected by one of the Psion Flayers in the Dust Palace. The Flayers are the official "Patient Zero" of this virus. The Flayers most likely contracted the virus while digging through the computer core. As the Flayers are technically the original patients, I would think that we could uncover more by focusing on the Flayers. The Flayers were digging around in the computer core of Charlemagne, the Warmind on Mars. So if the Flayers contracted the virus from Charlamagne, who is a Warmind which we know [i]very[/i] little about, then Charlemagne and the OWL Sector are most likely closely related and might have a bigger role in the Destiny Universe than we realize.