Make the emitters in one comp using something like ParticleWorld, lots of variables to play around with. Under producer, make the Y-radius either zero or something very low and it should have the look of being generated from the middle like that, where your line will be. Use a blending mode like screen when you put it in the comp with your bg and line.
I'm not on my comp with AE right now. This
tutorial should give you some ideas about getting the right look. There are a lot of good tuts on VCP that address one aspect of another of what you're trying to do.
Some kind of glow effect with the line. Once you figure that out I figure the coloring could just be added with an adjustment layer (or maybe just a solid) and play around with blending modes.
I'm still pretty new to AE but I'm learning a lot of stuff from this guys tutorials.