In silico analysis ompa and bam antigens of acinetobacter baumannii as a potential immunogen

Zahra Davoudi,1 Amirhossein taromchi ,2 Nariman mosaffa,3 Mojgan bandehpour,4,*

1. Department of medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences
2. Department of Medical Biotechnology and Nanotechnology, School of Medicine, Zanjan University of Medical Sciences
3. Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences
4. Department of Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences

Abstract

Introduction

Acinetobacter baumannii is one of the most successful nosocomial pathogens which resistant to almost all conventional antibiotics. its resistance to various antibiotics gives rise to the need of vaccine development against it. reverse vaccinology is a new method that explore proteome for novel vaccine candidates. outer membrane protein a (ompa) and β-barrel assembly machine (bam) proteins are the most promising vaccine candidate against, a. baumannii.. in this study, we attempted to analysis ompa and bam protein of a. baumannii as a potential vaccine candidate by using various online tools and programs

Methods

Amino acid sequence ompa and bam proteins of a. baumannii were retrieved and multiple sequence alignmented (uniprot, clustalx2). ompa and bama amino acide sequence analyzed for determaind various criteria to be a vaccine candidate (http://www.violinet.org/vaxign). epitope prediction and docking was performed using (iedb, cluspro v.2 online server). the results were clustered according to their binding energies. finally secondary and tertiary structure of the best proteins were predicted (i-tasser).

Results

Multiple sequence alignment of ompa and bam proteins sequence revealed the high conservation regions. vaxign analysis showed that ompa and bam has no trans-membrane helix, no similarity to human & mouse proteome. antigenicity and outer membrane localization predict that ompa and bam offers appropriate epitopes for immunity development against all species of acinetobacter. further, docking showed stable binding with low energies.

Conclusion

A protein must have certain properties to be an ideal vaccine candidate. an outer membrane protein has strong affinity to elicit immune response in host. protein should have less than two transmembrane helices. also, the presence of more than one trans-membrane helix often results in failure of recombinant protein isolation and purification. a protein with many t cell epitopes is preferred and it must not have similarity with host. these epitopes can be used as to make an epitope based sub-unit vaccine for broad range of acinetobacter species.

Keywords

Acinetobacter baumannii, in silico, reverse vaccinology, ompa, bam