[Immunology] ELISA protocol

[m s sudheesh]

Dear All,
  I am working on the development of nanoparticulate vaccine. While performing ELISA potocol the end point titre was expressed as the logarithm of the reciprocal of the last dilution which gave an optical density at 490nm above the optical density of negative control. What should be the negative control is it preimmune sera or the sera of animals trated with blank nanoparticles or the well containing only substrate. Kindly help me.

M.S.Sudheesh,Research Fellow,
Pharm Biotech Div, Department of Pharmaceutical Sciences, Dr. H.S.Gour University, Sagar, M.P,India,470001
Phone +91-9826415402