Klebsiella Antigen Identification and Immune Response: a Prospective Observational Study of Children with Klebsiella Infection

Klebsiella pneumoniae is a gram-negative bacteria responsible for an increasingly large number of antimicrobial resistant (AMR) infections worldwide. Crucially, the development of novel antibiotic compounds has stalled, limiting our ability to address AMR infection. Vaccination is a promising intervention to combat AMR, though identification of suitable antigen targets is required. The primary objective of this study is to identify immunogenic proteins on Klebsiella that will serve as vaccine candidates in future development. Blood samples and clinical bacterial isolates from 30 pediatric participants with serious Klebsiella infections will be used to identify antigenic proteins using traditional vaccinology principles. Bacterial antigens will be identified by immunoprecipitation with patient IgG followed by mass spectrometry and sequence comparison to known bacterial protein structures. Binding specificity of IgG to identified antigens will be assessed using serum plasmon resonance. Candidate antigens will be selected based on expression across Klebsiella serotypes, wherein candidates will display high prevalence and low genetic variability. Further, adaptive immune response to Klebsiella infection will be elucidated by comparing immune responses during acute and convalescent infection stages. Assays will include opsonophagocytic killing, phenotypic flow cytometry panels, and T cell proliferation following antigen stimulation. The establishment of the adaptive immune response to Klebsiella infection in children coupled with identification of novel antigenic proteins for future vaccine development with the specific intent of reducing AMR burden will lay the groundwork for study of similar gram-negative bacterial species with high morbidity and rates of AMR.