Analysis of RNA Polymerase Beta Subunit (rpoB) Gene Sequences to discriminate Brucella melitensis Genotypes in Clinical Iranian Isolates

Background and Aim The spread of Brucella infections in animals and humans has demonstrated the basic need for different regional / local reference laboratories to use validated species identification approaches to facilitate data exchange and comparison. The aim of this study was to evaluate the β subunit of RNA polymerase (rpoB) enzyme as a molecular marker in the differentiation of Brucella species and to determine the genotype of Brucella melitensis species using single nucleotide polymorphism (SNP) analysis.Methods: In this study, blood and cerebrospinal fluid samples were taken from ۵۰ patients with brucellosis. After culturing the samples in Brucella agar culture medium containing antibiotics, ۱۱ strains of Brucella bacteria were isolated and identified by classical and molecular biotyping methods. The rpoB gene of each of the isolates was then amplified and sequenced. Sequencing results were analyzed by Mega۶ program.Results: According to the results, rpoB gene was able to differentiate Brucella species from each other and other bacteria. While only one of the isolates belonged to Type ۱. Of the ۱۰ type ۲ rpoB strains, six specimens with only one unique type of point mutation were observed in codon ۹۸۵, which is a new type of genotype ۲.Conclusion: Our results show the high differentiation power of rpoB gene among Brucella isolates from some different regions of Iran, which led to accurate genotype determination and identification of these bacteria.

Keywords:

Brucellosis , RpoB , Brucella melitensis , single nucleotide polymorphism