Th1 and Th2 antibodies induced by immunization of mice with PLGA-encapsulated Chlamydia muridarum MOMP reveal immunodominant T- and B-cell epitopes that correlate with homologous vaginal protection 3110

Abstract Description Previously, we showed that female BALB/c mice that received either a homologous subcutaneous (SC) or heterologous intramuscular (IM-p) immunization with a nanovaccine comprised of the recombinant major outer membrane protein (rMOMP) of Chlamydia muridarum (Cm) encapsulated in poly(lactic acid-co-glycolic acid) produced robust humoral immune responses and were protected against a Cm vaginal challenge. Here, we used sera from SC and IM-p immunized mice against the full-length Cm rMOMP sequence to identify IgG as well as Th1 (IgG2a, IgG2b) and Th2 (IgG1) antibody binding epitopes employing high-density peptide microarrays. The microarrays were performed using a Cm sequence divided into 9 and 13 amino acids (aa) cyclized peptides with an offset of 1aa. Our data revealed strong recognition of conserved and variable domains (VD) by IgG antibodies produced in SC and IM-p immunized mice. The SC-induced IgG1 strongly recognized an 8aa sequence in VD1, suggesting a B-cell epitope. Interestingly, SC-induced IgG2b strongly recognized overlapping sequences in VD1 (15aa) and VD2 (16aa). The Immune Epitope Database (IEDB) epitope prediction tool also suggested the presence of T-cell epitopes in these sequences. However, IM-p-induced IgG2b and IgG1 showed moderate recognition of 5-8aa sequences in VD1-4. Follow-up with antigen-antibody ELISA showed SC-induced humoral responses to VD1 (15aa), suggesting that the vaginal protection in immunized mice was conferred from the VD1 region of MOMP. Funding Sources This research was supported by the National Institute Of Allergy And Infectious Diseases of the National Institutes of Health under Award Number R21AI111159, and the National Science Foundation NSF-EiR (2200529) grants. Topic Categories Vaccines and Immunotherapy (VAC)