RESUMEN
Acinetobacter baumannii, is among the highest priority bacteria according to the WHO categorization which necessitate the exploration of alternative strategies such as vaccination. OmpA, BamA, and Omp34 are assigned as appropriate antigens to serve in vaccine development against this pathogen. Experimentally validated exposed epitopes of OmpA and Omp34 along with selected exposed epitopes predicted by an integrative in silico approach were represented by the barrel domain of BamA as a scaffold. Among the 8 external loops of BamA, 5 loops were replaced with selected loops of OmpA and Omp34. The designed antigen was analyzed regarding the physicochemical properties, antigenicity, epitope retrieval, topology, structure, and safety. BamA is a two-domain OMP with a 16-stranded barrel in which L4, L6, and L7 were the longest loops of BamA in order. The designed antigen consisted of 478 amino acids with antigen probability of 0.7793. The novel antigen was a 16-stranded barrel. No identical 8-meric peptides were found in the human proteome against the designed antigen sequence. The designed construct was safe regarding the allergenicity, toxicity, and human proteome reactivity. The designed antigen could develop higher protection against A. baumannii in comparison to either OmpA, BamA, or Omp34 alone.
RESUMEN
Listeria monocytogenes, a facultative intracellular fast-growing Gram-positive food-borne pathogen, can infect immunocompromised individuals leading to meningitis, meningoencephalitis and septicaemias. From the pool of virulence factors of the organism, ActA, a membrane protein, has a critical role in the life cycle of L. monocytogenes. High mortality rate of listeriosis necessitates a sensitive and rapid diagnostic test for precise identification of L. monocytogenes. We used bioinformatic tools to locate a specific conserved region of ActA for designing and developing an antibody-antigen based diagnostic test for the detection of L. monocytogenes. A number of databases were looked for ActA related sequences. Sequences were analyzed with several online software to find an appropriate region for our purpose. ActA protein was found specific to Listeria species with no homologs in other organisms. We finally introduced a highly conserved region within ActA sequence that possess several antibody binding sites specific to L. monocytogenes. This protein sequence can serve as an antigen for designing a relatively cheap, sensitive, and specific diagnostic test for detection of L. monocytogenes.