The annual conference of the American Society for Mass Spectrometry is an event we look forward to each year. This year, we are ecstatic to have the opportunity to share our hometown, San Diego, with our friends and collaborators from around the world. You may have heard that San Diego in June is all gloom. Here’s where you can find a little sunshine throughout the week at the San Diego Convention Center:
Monday, June 4 Poster 064 “Serum Antibody Proteogenomics and the Hidden Repertoire”
Next-generation sequencing (NGS) of peripheral blood mononuclear cells is a common approach to approximate the repertoire; however it is a poor proxy for circulating antibodies. Sampling serum antibodies with mass spectrometry provides orthogonal data – directly querying the repertoire of interest. To deconvolve the complex serum repertoire, we employ proteogenomics and integrate the NGS repertoire as a database. We further analyze serum antibodies by partially reconstructing the ‘hidden’ serum antibodies by spectral networking.
The poster title suggests the topic will be the antibody repertoire, however, in the program the title is misprinted as the ‘Pepertoire’. We anticipate a fun mix of immunologists and pepper enthusiasts, so stop on by.
Monday, June 4 Poster 067 “Molecular Networking for the Characterization of Glycosylation on Antibodies”
Antibody glycosylation is known to have wide ranging effects on the function and efficacy of antibodies. Characterization of the repertoire of glycosylations on an antibody is a crucial step to monitor and understand activity. Identifying glycosylations using mass spectrometry is challenging due to the increased complexity of the spectrum which contains fragments of the peptide, the glycan, and the glycopeptide. In addition, popular fragmentation methods including CID, HCD, and ETD provide information on only a part of the whole molecule. Molecular networking is an approach to identifying spectra from related molecules, including different glycoforms on the same peptide. In this work we employ multiple fragmentation methods to each precursor ion, and use molecular networking to identify glycopeptides on antibodies.
Wednesday, June 6 Poster 062 “Applying de novo Top-Down and Middle-Down MS/MS Strategies Towards the Discovery of Novel Polyclonal Antibodies from Ebola/Zika Convalescent Sera”
This work is presented by our collaborator Dr. Adrian Guthals at Mapp Biopharmaceuticals. As new pathogens emerge and immuno-oncology targets are identified, a rapid, sensitive, and accurate method for interrogation of the long-term human polyclonal antibody (pAb) response and discovery of new potent mAbs is crucial. Here, we discuss how comprehensive MS/MS strategies can be used to de novo sequence the most abundant serum antibodies from human convalescent sera up to a year post infection, providing access to serum antibodies exported from the spleen, lymph nodes, mucosal surfaces, and bone marrow. Our results suggest that these potent pAbs are largely unavailable to genetic sequencing of peripheral B cells. Furthermore, we show that, following antigen-enrichment, the diversity of abundant antibodies in human convalescent sera can be surprising low and amenable to top-down MS/MS.
Visiting hundreds of posters each day is pretty daunting. Fortunately, we’ll be at our booth all day, every day. We will have reprints of our posters as well as live demonstrations of two of our solutions: Quorum Cloud and Alicanto.
Quorum Cloud™ is a powerful cloud platform for untargeted metabolomics analysis that utilizes the spectral networking approach. Each compound in your sample is assigned a unique molecular signature based on it’s precursor and fragmentation. This signature is informed by the structure of the compound, thereby enabling Quorum Cloud™ to identify structurally similar compounds using mass spectrometry, even when it doesn’t know what those compounds are. At the Digital Proteomics booth, we will demonstrate how Quorum Cloud™ can be used for metabolite identification, pharmacokinetics, and biomarker discovery.
Alicanto is our antibody discovery platform that uses mass spectrometry to identify high affinity monoclonal antibodies from serum. While millions of distinct B-cells are generated in response to an immunological challenge, only a fraction of the antibodies encoded by these cells are secreted at high levels in the serum. Alicanto identifies these antibodies that have been selected to defend against infection by the immune system. We’ve developed an interactive web-based viewer for inspecting the B-cell repertoire through the lens of the antigen-specific serum antibody repertoire. Stop by our booth to check out a demo of Alicanto.