ELISA for serum titer - Why preimmune serum has relative high background (Sep/28/2005 )

I am doing ELISA to test the serum titer with a purified recombinant protein as antigen. The post-immune sera look ok. But the preimmune sera also give relative high reading. I think my 2nd-ab is ok cause the non-1-Ab control (coated with antigen but only add 2-Ab, no 1-Ab) gave very reasonable reading.

Does anybody know how to reduce such a background? I don't even think I can make it
because I believe there is something in the preimmune serum cause such a background.

Serum contains a very high titre of antibody. It may be necessary to dilute the serum more to reduce nonspecific background from irrelevent antibodies in the serum. Try a dilution series until the background is low enough?

There should be non specificity. &checf ur patient or animal B4 taking pre immune sera. I thank ur animal was preinfected.