PepSeq as a highly multiplexed platform for melioidosis antigen discovery and vaccine development

Evan A Elko¹Charles Williamson¹Heather R Green²Marcellene A Gates-Hollingsworth²Georgia A. Nelson³Sujata G Pandit²Heather Mead⁴Christopher Allender⁴Celeste Woerle⁵Mark John Mayo⁵Bart J Currie⁵David P AuCoin²John Altin⁴Paul Stephen Keim^1,4,6Erik W Settles^1,6*Jason T Ladner^1,6*

• ¹The Pathogen and Microbiome Institute (PMI), Northern Arizona University, Flagstaff, Arizona, United States
• ²Department of Microbiology and Immunology, School of Medicine, University of Nevada, Reno, Nevada, United States
• ³Pathogen and Microbiome Division, Translational Genomics Research Institute, Flagstaff, Arizona, United States
• ⁴Division of Pathogen Genomics, Translational Genomics Research Institute, Flagstaff, Arizona, United States
• ⁵Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia
• ⁶Department of Biological Sciences, College of the Environment, Forestry, and Natural Sciences, Northern Arizona University, Flagstaff, Arizona, United States

Vaccination aims to prevent or mitigate disease by priming the immune system prior to infection.While historical vaccine development relied mostly on trial-and-error, modern approaches have become more directed. By leveraging our growing understanding of pathogen biology and immune correlates of protection, we can design vaccines in ways that promote protective responses. However, the complexity of many pathogens (e.g., bacteria and fungi), as well as our immune responses against them, continue to present important challenges for vaccine development. Here, we demonstrate the utility of the PepSeq platform for highly multiplexed serology to both broadly and finely characterize antibody responses against complex pathogens, using the bacterium, Burkholderia pseudomallei, as a case study. Using a variety of custom PepSeq libraries, we identify novel B cell epitopes and finely characterize the epitopes of three monoclonal antibodies against the B. pseudomallei GroEL protein.