Phenotypic and genotypic characterization of Brucella abortus biovar 4 isolates from cattle in Brazil

Abstract

The aim of the present study was to characterize (phenotypically and genotypically) two strains of Brucella abortus identified as belonging to biovar 4 isolated from cattle in Brazil. The strains were isolated from cervical bursitis from cattle in the states of Pará and Rio Grande do Sul, respectively. In the phenotypic identification, the isolates were positive in CO2 requirement, produced H2 S, were resistant to basic fuchsin (20 µg / mL) and sensitive to thionin (20 µg / mL and 40 µg / mL) and presented M surface antigen, but A surface antigen is absent. The isolates were positive in the PCR for the bcsp31 gene (genus-specific) and in the AMOS-enhanced PCR, both isolates showed a band profile consistent with B. abortus biovar 1, 2 or 4. Moreover, both isolates also showed restriction patterns identical to the reference strain when tested by the omp2b PCR-RFLP. In genotyping using Multiple Locus Variable Number of Tandem Repeat (VNTR) Analysis-MLVA (MLVA16), the isolates showed differences in several loci (Bruce42, Bruce19, Bruce04, Bruce16 and Bruce30); by Multiple Locus Sequence Typing (MLST), they also exhibited differences in sequence type (ST), strain 16/02 ST1 (2-1-1-2-1-3-1-1-1) and strain 128/11 ST (22-1-1-8-9-3-1-1-1). The extensive typing of B. abortus strains isolated from cattle in Brazil using different approaches confirmed the occurrence of rare B. abortus biovar 4 in the country.