In-Silico Assessment of Lethal Factor (LF) of Bacillus anthracis Exotoxin for its Suitability as a Diagnostic Candidate for Anthrax in Livestock

Anthrax is a highly fatal disease of animals and humans caused by Bacillus anthracis. The bacteria is a Gram-positive capsulated spore forming which harbors two plasmids pX01 and pX02, responsible for the virulence factors encoding for exotoxins and capsule respectively. Although several studies in the past deciphered the various aspects of the disease etiology and pathogenesis, but these have mainly been focused on development of a suitable field applicable rapid diagnostic assays for the detection of antigen and/or antibodies. The exotoxins of bacteria, protective antigen (PA) and lethal factor (LF) have been reckoned as key candidates for the development of diagnostics and vaccines. In this study, the gene encoding for lethal factor has been analyzed with in-silico approach using various prediction tools to assess the antigenic nature and its suitability as a candidate for diagnosis and prophylaxis. In comparative sequence analysis, anthrax vaccine strain (sterne) and the field isolates/strains from other countries available in NCBI database were analyzed by multiple sequence alignment. The LF protein was found to be highly conserved across the isolates/strains with 95.4-100% identity at the sequence level. The prediction tools revealed the presence of B cell and T cell epitopes. The LF protein lacks allergenic characteristics as revealed from the absence of IgE epitopes. The protein was predicted to be soluble in recombinant form with absence of super coil structure which may lead to aggregative tendency. In conclusion, the lethal factor (LF) protein of Bacillus anthracis was predicated to have all the essential characteristics to be an ideal diagnostic candidate.