Grouped immunogens are hierarchically recognized by host to generate antibodies

Area of Science:

• Immunology
• Microbiology
• Bioinformatics

Background:

• Microorganisms possess numerous proteins that can potentially trigger host immune responses.
• It remains unclear if hosts recognize all microbial proteins simultaneously or in a sequential manner.

Purpose of the Study:

• To investigate the hierarchical recognition of microbial antigens by the host immune system.
• To analyze the characteristics of recognized immunogens across different recognition hierarchies.

Main Methods:

• Immunization of mice with pooled outer membrane (OM) proteins from *Escherichia coli*.
• Analysis of antisera using protein microarrays to identify recognized proteins.
• Iterative removal and re-pooling of recognized proteins for subsequent immunization cycles.
• Bioinformatics analysis of B cell epitope scores and Gene Ontology (GO) functional categories.

Main Results:

• Only 18 out of 68 *E. coli* OM proteins were recognized in the first immunization hierarchy.
• Subsequent immunization cycles identified additional hierarchies of immunogens, with decreasing numbers of newly recognized proteins.
• A negative correlation was observed between B cell epitope scores and the hierarchy of immunogen recognition.
• Proteins involved in transport functions were more prevalent in earlier hierarchies, while metabolic process proteins were less common.

Conclusions:

• The host immune system employs a hierarchical recognition strategy for antigens, leading to sequential antibody responses.
• This hierarchical recognition influences the types of proteins targeted in different stages of the immune response.
• Understanding this hierarchy is crucial for deciphering differentially neutralizing antibody responses during microbial infections.