Enzyme-linked immunosorbent assay (ELISA) and blocking with bovine serum albumin (BSA)--not all BSAs are alike

J Immunol Methods. 2012 Oct 31;384(1-2):148-51. doi: 10.1016/j.jim.2012.06.009. Epub 2012 Jun 23.


The enzyme-linked immunosorbent assay (ELISA) is an extremely common and powerful laboratory technique for detecting proteins by antibodies. Researchers frequently use bovine serum albumin (BSA) as a blocking agent to prevent non-specific binding of antigens and antibodies to the microtiter well. While studying the interactions of the vaccinia virus complement control protein (VCP) with complement, we found non-specific binding of VCP to BSA and identify a BSA preparation that did not result in non-specific binding. This work draws attention to the fact that not all BSA preparations are alike. It also highlights the need to perform critical controls to ensure that ELISA reactants do not inappropriately bind to the blocking agent.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Binding, Competitive / immunology
  • Cattle
  • Complement C3b / immunology*
  • Complement C3b / metabolism
  • Cross Reactions / immunology
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Humans
  • Protein Binding / immunology
  • Reproducibility of Results
  • Serum Albumin, Bovine / immunology*
  • Serum Albumin, Bovine / metabolism
  • Viral Proteins / immunology*
  • Viral Proteins / metabolism


  • Viral Proteins
  • complement-control protein, Vaccinia virus
  • Serum Albumin, Bovine
  • Complement C3b