In silico analysis of virulence genes in an emerging dental pathogen A. baumannii and related species

Acinetobacter baumannii is an opportunistic pathogen which has recently been categorized as a high risk pathogen by World Health Organisation (WHO). The microbe has stealthily entered the oral cavity and has established itself as a potential pathogen by acquiring drug resistance and expression of several virulence genes. Surveillance on the type of virulence factors harboured by the organism will enable us to comprehend the mechanism of pathogenesis. The study was performed to screen for the presence of crucial virulence factors associated with Acinetobacter spp. as reviewed from the literature by employing computational tools.

Nineteen genome sequences of Acinetobacter spp. with the predominance of different strains of A. baumannii were classified phylogenetically into clusters using in silico restriction digestion and pulse field gel electrophoresis (PFGE). Further, the frequency of common virulence genes in the genome of various Acinetobacter spp. was recorded using in silico PCR analysis.

Based on PFGE pattern and phylogenetic tree the genomes of A. baumannii were clustered into 4 genotypes (G1-G4). Two species were excluded from the list since they were negative for almost all the virulence genes tested. Frequency of virulence genes in each of the 17 genomes analysed, found ompA and smpA to be the major virulence factors in A. baumannii and related species. Acinetobacter spp. belonging to genotypes 2 and 3 were found to harbour 1-15 and 6-10 potential genes encoding virulence factors respectively.

The present study showed numerous virulence genes in genomes analysed. In silico analysis of these virulence genes can be used as candidates to build novel therapeutic targets against the pathogen. An extensive study on the functional role of these genes could aid in stalling the propagation and dissemination of A. baumannii among susceptible individuals.