Submitted May 17, 2007
Accepted August 21, 2007
Accurate identification of paraprotein antigen targets by epitope reconstruction
Seshi R Sompuram, Gerassimos Bastas, Kodela Vani, and Steven A Bogen*
Medical Discovery Partners LLC, Boston, MA, United States
Department of Pathology & Laboratory Medicine, Boston University School of Medicine, Boston, MA, United States
* Corresponding author; email: sbogen{at}bu.edu.
We describe the first successful clinical application of a new discovery technology - Epitope-Mediated Antigen Prediction (E-MAP)- to the investigation of multiple myeloma. Until now, there has been no reliable, systematic method to identify the cognate antigens of paraproteins. E-MAP is a variation of previous efforts to reconstruct the epitopes of paraproteins, with the significant difference that it provides enough epitope sequence data so as to enable successful protein database searches. We first reconstruct the paraprotein's epitope by analyzing the peptides that strongly bind. Then, we compile the data and interrogate the non-redundant protein database, searching for a close match. As a clinical proof-of-concept, we apply this technology to uncovering the protein targets of paraproteins in multiple myeloma (MM). E-MAP analysis of two MM paraproteins identified human cytomegalovirus (HCMV) as a target in both. E-MAP sequence analysis determined that one paraprotein binds to the AD-2S1 epitope of HCMV glycoprotein B. The other binds to the amino terminus of the HCMV UL-48 gene product. We confirmed these predictions using immunoassays and immunoblot analyses. E-MAP represents a new investigative tool for analyzing the role of chronic antigenic stimulation in B lymphoproliferative disorders.
