Mecha anime with a "mind control virus" Before I describe what little more about it I know, let me clear two things up. I will be referring to a "virus", but I don't know what it actually is. I may sometimes say Gundam instead of mech. That's because I just spent 30 minutes looking up Gundam, not because it's a Gundam anime (although it might be).

So, I know it's a mech anime. When they enter the mech, they pass through a circle that applies a form fitting suit that they use to control the mecha. (I'm actually not totally sure about this).

One of the episodes involved a conference and/or other group of people collected together talking about the "virus". One of the attendees is infected (and there's something about them they have to hide to prevent people from finding this out).

The "virus" bas stages (I think) eventually takes over the infected (while they are in a mecha), and the infected loses control (becomes controlled?). If I recall correctly, the inside of the mecha now looks like a fleshy hell pit created by the "virus".

I'm fairly certain it was on Toonami. I'm 100% certain it was on T.V. in the US sometime between 1998 and 2005.
Your anime might be: Mobile Fighter G Gundam



Firstly it was aired in Toonami in 2002, so it fits the initial bill.

Then in the wikipedia page, The plot section has this one specific fragment:


  As they encounter Gundam pilots who had come in contact with the Dark
  Gundam, Domon and Rain learn of its unique cellular properties to
  regenerate, multiply, and evolve by infecting organic matter and
  causing violent behavior in living things.


So we know that this anime is about mechas and there is a virus thing, namely the Dark Gundam, that has abilities to corrupt organic matter and evolve in/with it (or something along those lines).

Then as I searched for footage of the anime, I came upon this video of the first episode which in its first seconds shows the character going through a circle in order to wear a suit, just like you also told.

I'm not sure about the meeting part, for I haven't watched it, but as for everything else you've told, it's a dead giveaway.