With regard to using PVP there is a paper in Analytical Biochemistry
208:397-99, 1993 on "PVP as a blocking agent in immunochemical studies" byJW
This paper recommends the use of PVP in conjunction with Tween 20 in Western
Blots as it gives a high signal to background ratio. I use this combination
in an indirect competitive ELISA for sporidesmin (a mycotoxin) and have
found that it works very well.
Regards Dr Roger Collin
AgResearch, Hamilton, New Zealand