Reused plot device from Alien 3?

Hi, ca va, wie gehts, everybody. Still wet behind the ears here so forgive me if this is something that's been brought up before, but like most I have my own hypothesis as to parts of Prometheus's plot. If anyone remember Alien 3 it went through development hell, and in an early draft William Gibson wrote that the Alien's infected humans through an ebola-like virus that turned them into Alien pawns (like in the Thing). You can see so many hints towards a communicable alien-thing in the Prometheus trailers - you can see Fifield with something crawling under his skin (you can identify him as part of his name is visible on his forehead, and by his mohawk haircut), and you can see a former astronaut in the spacesuit-uniform attack the others (my moneys on Fifield). You can see David squeezing an alien goo and watching the alien 'worms'. Am I deliberately trying to find patterns with the Alien series or does this sound plausible? Any other theories for the alien antagonist?