[Histonet] specific Ig detection

[JEFF TATUM ZELIADT]

I am a student taking an immunobiology course.  I was wondering if someone 
could help point me in the right direction.  I have an unknown infections 
agent, I know that it produces anaphlylaxis and will produce IgE and IgA.  
If I isolate the IgE's from the serum I will get all IgE's even those not 
specific to the bug.  How can I seperate the two and get the specific 
antigen?  Can I use a protein which would be specific to the bug but how do 
I know what protein?