Replicable libraries having discrete members in defined locations for screening for antigens to a pathogenic organism are provided. Also provided are methods for using such libraries as well as a specific antigen, CT788, which induces T-cell activation during a Chlamydia infection.

Replicable libraries having discrete members in defined locations for screening for antigens to a pathogenic organism are provided. Also provided are methods for using such libraries as well as a specific antigen, CT788, which induces T-cell activation during a Chlamydia infection.

Disclosed herein is a Chlamydia-activated B cell (CAB) platform. Also disclosed is a method of enhancing a population of B cells, comprising exposing said B cells to Chlamydia spp. under conditions suitable to enhance the population of B cells, such that expansion and differentiation of said B cells takes place, and said B cells are exposed or crosslinked to an antigen. Also disclosed are methods of producing said CABs, and treating a subject in need thereof with said CABs.