Study on polymorphism of Brucella melitensis biovar 3 strains isolated from Guangdong province

Objective To investigate the polymorphism of Brucella melitensis biovar 3 （ B.melitensis biovar 3） strains isolated from Guangdong province .Methods PCR assays followed by agar-ose gel electrophoresis and capillary electrophoresis based on the multiple locus variable number of tandem repeats （VNTR） analysis （MLVA） were performed to analyze 43 clinic isolates of B.melitensis biovar 3 strains isolated from clinical patients in Guangdong province .Results MLVA typing showed that the simi-larities of the analyzed locus among 43 strains of Brucella ranged from 68.2%to 100%.32 genotypes identi-fied among the isolates were identical （100%similarity）.27 out of 43 strains （62.8%） were single geno-types, while the other 16 strains （37.2%） belonged to 5 other genotypes with 2 to 5 strains in each of them . Conclusion B.melitensis biovar 3 isolates showed polymorphism distribution in Guangdong province as in-dicated by MLVA typing analysis .Single-genotype isolates accounted for 62.8% of all studied strains.No predominant genotype was found among all isolates . Key words: Brucella melitensis ;  MLVA;  PCR;  Subtyping