Prediction of B-cell epitope by in silico analysis of Mycobacterium tuberculosis Ag85B antigen

Mycobacterium tuberculosis (Mtb) is a causative pathogen of tuberculosis (TB) that emerges as one
of the deadliest communicable diseases in Indonesia. The quest for protein biomarkers for TB has been
conducted in order to develop a TB diagnostic kit and a TB vaccine. One of the abundant biomarkers in
the TB infected human serum is the Ag85B antigen. In this study, we employed immunoinformatic
prediction tools such as Ellipro and VaxiJen to predict the B-cell epitopes of Ag85B wildtype and
multidrug resistance type (mutant). We then performed molecular docking simulation to evaluate the
predicted epitopes using HADDOCK. The screening of both continuous and discontinuous B-cell
epitopes using criteria-based analysis resulted in the eight linear epitopes and two conformational epitopes
in Ag85B with high antigenicity. The in silico analysis showed no major differences between Ag85B
wildtype and Ag85B mutant, implying Ag85B a good target for TB vaccine candidates but not for a specific
biomarker that differentiates wild-type and mutant TB.