MIRU-VNTR typing produced 16 distinct genotypes, with 53 isolates forming eight of the groups, and individual isolates with unique VNTR profiles forming the remaining eight groups. The allelic diversity of each VNTR locus was calculated and only two of the 12-MIRU-VNTR loci presented scores with either a moderate (0.4, MIRU16) or high (0.6, MIRU26) discriminatory index (h). Both typing methods produced similar discriminatory indexes (spoligotyping h = 0.85; MIRU-VNTR h = 0.86) and the combination of the two methods increased the h value to 0.94, resulting in 29 distinct patterns. These results confirm that spoligotyping and VNTR analysis are valuable tools for studying the molecular epidemiology of M. bovis infections in Brazil. Key words: Mycobacterium bovis -spoligotyping -MIRU-VNTR typing -bovine tuberculosis -molecular epidemiologyGenotyping of M. bovis from Brazil • Patrícia Martins Parreiras et al. 65While IS6110-RFLP lacks resolution in this species, spoligotyping has been demonstrated to be a fast and cost-effective method for first-line typing (Haddad et al. 2004). The MIRU-VNTR typing procedure has been extensively evaluated in M. tuberculosis and the recent data available about this method on M. bovis strains confirmed its considerable power of discrimination (Sola et al. 2003, Michel et al. 2008, 2010. Smith et al. (2006) inferred that a combination of spoligotyping and VNTR typing resulted in the simplest and most cost-effective method for routine molecular typing and epidemiological tracing of bovine TB in Great Britain.Some previous studies have successfully employed techniques such as IS6110-RFLP and spoligotyping to genotype M. bovis strains isolated from cattle in Brazil (Zanini et al. 2001, Rodriguez et al. 2004), but as far as we know, no data exist on genotyping of M. bovis by combining spoligotyping and MIRU-VNTR typing in our country. We aimed to use spoligotyping and MIRU-VNTR typing to assess the genetic diversity of Brazilian M. bovis isolates. MATERIALS AND METHODS Sampling and conventional procedures -During 2001and 2002, tissue samples from cattle with lesions suggestive of TB were collected immediately after slaughter at the time of inspection in abattoirs. The study samples were collected in abattoirs that followed slaughter inspection procedures from the states of Amazonas (AM), Paraíba (PB), Distrito Federal (DF), Mato Grosso do Sul (MS), São Paulo, Santa Catarina (SC) and Minas Gerais (MG). The sampled specimens from respective carcasses were pooled, put on ice and sent to the Laboratório Nacional Agropecuário de Minas Gerais (Pedro Leopoldo, MG), where they were processed for inoculation in Stonebrink culture medium (Mota 1985). The cultures were incubated at 37ºC and verified for bacterial growth every week for a period of at least two months. Bacterial isolates were submitted to standard procedures for differentiation of certain species of the MTBC, including the evaluation of niacin production, nitrate reductase activity, Tween hydrolysis, catalase activity at 68ºC and resis...
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