Computer aided subunit vaccine design against pathogenic Leptospira serovars

Epitopes of Leptospira inducing CD4(+) T-cell responses by binding to human MHC molecules could critically contribute to the development of subunit vaccines for leptospirosis. Herein, we have identified unique vaccine peptides from outer membrane proteins (OMPs) common to four sequenced pathogenic Leptospira serovars through in silico reverse vaccinology technique. The OMPs were explored for probable antigens using jemboss and screened in ProPred subsequently to predict thirty HLA-DRB epitopes. The HLA-DRB epitopes were validated through published positive control (HA307-PKYVKQNTLKLAT-319), SYFPEITHI and immune epitope database (IEDB) to list twelve epitopes as putative subunit vaccine peptides from nine OMPs. Cation efflux system membrane protein (czcA) having four subunit vaccine peptides, was modeled in Modeller9v7 and evaluated through Procheck, ProSA and ProQ. The HLA-DRB alleles and czcA 3D interactions were studied using Hex 5.1. Further, the T-cell epitopes present in czcA were docked individually with HLA-DRB alleles. The docking result revealed that czcA and its epitopes were interacting well with HLA-DRB alleles, hence would certainly produce cell mediated immune response in host. Thus, czcA and its four subunit vaccine peptides would be ideal T-cell driven efficacious vaccine against leptospirosis.