Optimal epitope composition after antigen screening using a live bacterial delivery vector: application to TRP-2.

Area of Science:

• Immunology
• Oncology
• Microbial Engineering

Background:

• Immunotherapy using tumor-specific cytotoxic T-lymphocytes (CTL) is a promising anti-cancer strategy.
• Attenuated bacteria offer advantages as engineered vaccine vectors, stimulating innate immunity.
• Pseudomonas aeruginosa's type III secretion system (TTSS) can be utilized for in vivo antigen delivery.

Purpose of the Study:

• To develop and evaluate an attenuated live bacterial vector for delivering tumor antigens against glioma.
• To assess the impact of antigen length and epitope composition on CTL immunity and anti-tumor responses.
• To identify key characteristics of antigens that enhance anti-tumor immunity.

Main Methods:

• Development of an attenuated live bacterial vector using Pseudomonas aeruginosa TTSS.
• In vivo vaccination against glioma cells using an inducible plasmid expressing tumor antigens (TRp-2, gp100, MUC18) of varying lengths.
• Analysis of CTL immunity, T-cell receptor (TCR) repertoire diversity, and anti-tumor efficacy.

Main Results:

• Similar CTL immunity and TCR repertoire diversity were observed for TRP2(125-243), TRP2L(125-376), and TRP2S(291-376) vaccines.
• Only immunization with the longer peptide TRP2L(125-376) induced significant anti-tumor immunity.
• Longer peptides with immunodominant/cryptic CD8(+) and strong CD4(+) Th epitopes improved anti-tumor immunity.

Conclusions:

• Antigen peptide length and epitope composition are critical for inducing effective CTL-mediated anti-tumor immunity.
• The developed bacterial vector is a versatile platform for rapid screening of antigens for cancer vaccines.
• TRP2L(125-376) demonstrates potential as a therapeutic antigen for glioma treatment.