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Molecular epidemioloic analysis of Mycobacterium bovis isolates from Mexico

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  • 1 CENID-Microbiología, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Km Palo Alto, D.F. CP 05110, México.
  • | 2 Departments of Environmental Health, College of Veterinary Medicine and Biological Sciences, Colorado State University, Ft Collins, CO 80523.
  • | 3 Departments of Microbiology, College of Veterinary Medicine and Biological Sciences, Colorado State University, Ft Collins, CO 80523.
  • | 4 Departments of Environmental Health, College of Veterinary Medicine and Biological Sciences, Colorado State University, Ft Collins, CO 80523.
  • | 5 FCN, Universidad Autonoma de Querétaro, Querétaro, Qro, México.
  • | 6 National Veterinary Services Laboratories, APHIS:USDA, Ames, IA 50010.
  • | 7 Departments of Environmental Health, College of Veterinary Medicine and Biological Sciences, Colorado State University, Ft Collins, CO 80523.

Abstract

Objective—To assess phylogenetic relationships among Mycobacterium bovis isolates by use of random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) fingerprinting and to relate genetic profiles of isolates to epidemiologic characteristics.

Animals—400 cattle with tuberculosis.

ProcedureMycobacterium bovis was isolated from various organs of cattle slaughtered in 6 geographic regions of Mexico. Most cattle were adult Holsteins from large herds that did not participate in a tuberculosis control program. Four random primers and 2 selected primers were used in RAPD-PCR fingerprinting of 88 isolates. Pairwise genetic distance between isolates was obtained and subjected to cluster analysis with bootstrapping to test for levels of support.

Results—98 different fragments were obtained; there was broad genetic diversity among isolates, and each isolate had a unique RAPD-genotype, including those originating from the same herd. Clustering by geographic location, affected organ, or severity of lesion was not detected. Linkage disequilibrium analysis suggested that M bovis was highly clonal and that mutations develop at a rapid rate among isolates.

Conclusions and Clinical Relevance—Use of RAPDPCR could not differentiate M bovis isolates by epidemiologic characteristics or identify common sources of infection. (Am J Vet Res 2000;61:90–95)

Abstract

Objective—To assess phylogenetic relationships among Mycobacterium bovis isolates by use of random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) fingerprinting and to relate genetic profiles of isolates to epidemiologic characteristics.

Animals—400 cattle with tuberculosis.

ProcedureMycobacterium bovis was isolated from various organs of cattle slaughtered in 6 geographic regions of Mexico. Most cattle were adult Holsteins from large herds that did not participate in a tuberculosis control program. Four random primers and 2 selected primers were used in RAPD-PCR fingerprinting of 88 isolates. Pairwise genetic distance between isolates was obtained and subjected to cluster analysis with bootstrapping to test for levels of support.

Results—98 different fragments were obtained; there was broad genetic diversity among isolates, and each isolate had a unique RAPD-genotype, including those originating from the same herd. Clustering by geographic location, affected organ, or severity of lesion was not detected. Linkage disequilibrium analysis suggested that M bovis was highly clonal and that mutations develop at a rapid rate among isolates.

Conclusions and Clinical Relevance—Use of RAPDPCR could not differentiate M bovis isolates by epidemiologic characteristics or identify common sources of infection. (Am J Vet Res 2000;61:90–95)