¹Laboratory of Infectious Diseases, Hepatitis Viruses and Molecular Hepatitis Sections, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA

Correspondence: Dr Y-H Zhou, Laboratory of Infectious Diseases, Hepatitis Viruses and Molecular Hepatitis Sections, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 50, Room 6535, 50 South Drive MSC-8009, Bethesda, MD 20892, USA. E-mail: yzhou@niaid.nih.gov

Received 16 June 2006; Accepted 20 July 2006; Published online 28 November 2006.

Abstract

Epitope mapping (identification of an antigenic site recognized by an antibody) is an important component of vaccine development and immunological assays. It is widely accepted that in Western blots, antibodies react exclusively with continuous epitopes: discontinuous epitopes are assumed to be irreversibly destroyed by electrophoresis under the denaturing conditions used for sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Here, we demonstrate that the epitopes recognized by four different monoclonal antibodies were identified as discontinuous epitopes when characterized by radioimmunoprecipitation assays and enzyme-linked immunosorbent assays, yet each of these antibodies reacted with the corresponding antigen on Western blots. Reaction on Western blots may be due to epitope renaturation during or after the transfer of the protein to a membrane. Therefore, positive reactions on Western blots do not necessarily indicate that epitopes are continuous and this caveat should be kept in mind while characterizing them.