Abstract
Brucellosis is an endemic infection in Iran and causes important economic losses in livestock as well as a serious health problem in humans. The aim of the current study was to evaluate the genetic diversity of Brucella spp. isolated from livestock and human in Iran through the multi locus sequence analysis (MLST). A comprehensive phylogenetic analysis has been achieved to understand the relationship of Brucella genotypes identified in Iran to those originating from different regions across the globe. A total of 30 Brucella isolates were recovered from 8 milk samples collected from cows (n=7) and camels (n=1), human blood samples (n=12), cow lymph nodes (n=4), and 6 aborted fetuses from sheep (n=3), cows (n=2) and goat (n=1). MLST -9 analysis was used to characterize the genetic diversity among B. abortus and B. melitensis isolates. Classical biotyping and molecular identification through AMOS PCR and Bruce-ladder PCR showed that all Brucella isolates were either B. abortus or B. melitensis. B. melitensis was associated with ovine/caprine, camel, cow samples, and the majority of human blood samples (n=12). In contrast, B. abortus was related to bovine samples and a single human sample, indicating that both B. melitensis and B. abortus may contribute to the human brucellosis burden in Iran. B. melitensis isolates comprised 4 MLSA-9 genotypes, the common and globally distributed ST8, ST7, ST71, and ST102. However, four B. melitensis isolates represented a novel ST from human and cow sources. B. abortus isolates belonged to the common MLSA-9 genotypes ST1 and ST2 with relationships to biotype and other PCR-based typing methods. The current results represent the first molecular characterization of Brucella strains circulating in Iran and provide the basis for further studies examining the molecular epidemiology of Brucella spp. in Iran and their relationships to those circulating worldwide.
