Molecular Typing of Brucella Species Isolated from Humans and Animals Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Technique

[Background]Brucellosis is a zoonotic disease that causes major economic and public health problems. It is one of the most important diseases in humans and domestic animals. Hence, the exact identification of Brucella spp. is important for strategies of treatment and control. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) is one of the molecular techniques characterized by amplification of deoxyribonucleic acid (DNA) sequence and restriction enzyme digestion.[Objectives]This study aimed at identifying genetic polymorphisms of omp2a genes among 90 Brucella isolated from humans and animals, using the PCR-RFLP method.[Methods]Ninety Brucella spp. isolated from humans and animals in two different regions of Iran were used in this study. Biochemical tests and the Brucella omp2a (1100 bp) gene-PCR was used for identification of Brucella isolates. Polymerase Chain Reaction products were digested by restriction endonuclease enzyme pstI and gene sequencing analysis was carried out for molecular typing of Brucella strains. Therefore, genetic relatedness was revealed by a dendrogram.[Results]Analysis of the 90 Brucella strains by biochemical tests, PCR, and PCR-RFLP methods with PstI enzyme and omp2a sequencing showed four unique RFLP Profiles (P1-P4). Seventy-nine (87.8%) of the Brucella isolates belonged to B. melitensis strain 20236. From 30 animal isolates, nine (30%) belonged to B. melitensis biovare1 and two (6.6%) to B. abortus strain. According to the RFLP dendrogram, group 1 and 2 had higher genetic relatedness similarity.[Conclusions]The results showed B. melitensis strain 20236 was the predominant strain among human and animal Brucella isolates. Likewise, according to dendrogram results, the PCR-RFLP technique was not able to separate human and animal species of B. melitensis from B. abortus.