The 4th log entry under Glory 2.1 is a debrief from Owl Sector member Shun to Ikora Rey on what they are finding in the old Golden Age research notes at the Dust Palace.
It talks about a golden age patient, Patient E.
Here is what is says:
[spoiler] Patient E, Jun, has been uncooperative. Laughed unpleasantly when I told him he would receive Glory 2.1.
"You're running prototypes in parallel because it's cheaper and it's faster, he said. No ethics board on earth would approve. But I don't have a choice. I'm neck deep in debt to Clovis Bray."
I wish we would have tweaked these elixirs to modify disposition.[/spoiler]
In caydes journal (link http://www.destinypedia.com/Cayde's_Treasure_Island_Book ), we know that Cayde owed Clovis bray a big debt as a human, and it would be forgiven. Next we know, Cayde is an exo. It is heavily implied Cayde agreed to the exo experiment to pay that debt, which matches the spoiler above.
So Patient E could easily be Cayde, before he was an exo. Which would put his name as Jun.
It is also possible it is another individual in a similar situation as Cayde, but heavily implies it's Cayde because the personality in the spoiler above is very much like his.
This links Willa Bray, Dr Shirazi, Cayde and the exo creation program. Which makes sense because when people glitched into the lab below the dust palace, exo science is written all over the walls.
So whatever we are being infected by appears to be a byproduct of the technology that created exos
EDIT: One more little part of that same record. Shun states "this kind of coercion isn't a known Clovis Bray practice." Meaning coercing people to be experimented on to pay a debt. To which Ikora responds "Not in the [i]books[/i] you read perhaps."
Nice little nod to the book, caydes Treasure island book (aka caydes journal) which I linked above in which he did document being coerced by Clovis to pay his debt.
-
I don't know much of cayde's back story, but did read the owl sector transcripts. Why wouldn't he say "hey I know about this stuff I was one of the tests way back when"?