In silico approach for future development of subunit vaccines against Leptospira interrogans serovar Lai

Leptospirosis continues to have major impacts on people of developing countries with inestimablemorbidity and mortality. As current leptospirosis vaccination is relatively unsuccessful, development ofefficacious vaccines through novel means became utmost priority for prevention of frequent outbreaks of thedisease. Herein, MHC class II restricted peptide epitopes were identified from pathogenic Leptospiralmembrane proteins to suggest T-cell epitope driven leptospirosis vaccines through reverse vaccinology. Theproteome of Leptospira interrogans serovar Lai was screened to select 137 membrane proteins. JembossAntigenic server was employed to find antigenic peptides, followed by ProPred analysis to predict 30 shortpeptides having strong binding affinity with HLA DRB1*0101, DRB1*0401 and DRB1*1501 alleles.Predictions were revised to pick antigenic peptides with same core region binding with the selected HLADRB1alleles and ten such peptides were found from seven proteins. Further, to confirm the interaction atstructure level, Leptospira excinuclease ABC subunit B protein having short T-cell antigenic peptide (133-REDVVIVSSVSCIYGLG-149) was modeled using Modeller9v7. The model reliability was evaluated throughProcheck, ProSA and ProQ. Docking calculations for selected HLA DRB1 alleles (receptor) and modeledLeptospira excinuclease ABC subunit B protein (ligand) were carried out using Hex 5.1. The protein -proteininteraction revealed that the core region (136-VVIVSSVSC-144) of the antigenic peptide (133-REDVVIVSSVSCIYGLG-149) was well interacting with the receptors. Through the reverse vaccinologyapproach and docking studies, the short antigenic peptide 133-REDVVIVSSVSCIYGLG-149 of Leptospiraexcinuclease ABC subunit B is proposed as a potential novel T-cell driven subunit vaccine againstleptospirosis.