Monitoring of transmission of tuberculosis between wild boars and cattle: Genotypical analysis of strains by molecular epidemiology techniques

An epidemiological survey for the monitoring of bovine tuberculosis transmi ssion was carried out in western Liguria, a region in northern Italy. Fifte en Mycobacterium bovis strains were isolated from 63 wild boar samples (62 from mandibular lymph nodes and 1 from a liver specimen). Sixteen mediastin al lymph nodes of 16 head of cattle were collected, and 15 Mycobacterium bo vis strains were subsequently cultured. All M. bovis strains isolated from cattle and wild boars were genotyped by spoligotyping and by restriction fr agment length polymorphism (RFLP) analysis with the IS6110 and IS1081 probe s. All M. bovis strains showed the typical spoligotype characterized by the absence of the 39 to 43 spacers in comparison with the number in M. tuberc ulosis. A total of nine different clusters were identified by spoligotyping . The largest cluster included 9 strains isolated from mild boars and 11 st rains isolated from cattle, thus confirming the possibility of transmission between the two animal species. Fingerprinting by RFLP analysis with the I S6110 probe showed an identical single-band pattern far 29 of 30 strains an alyzed, and only 1 strain presented a five-band pattern, The use of IS1081 as a second probe was useful for differentiation of M. bovis from hi. bovis BCG but not for differentiation among M. bovis strains, which presented th e same undifferentiated genomic profile. In relation to the epidemiological investigation, we hypothesized that the feeding in pastures contaminated b y cattle discharges could represent the most probable route of transmission of M. bovis between the two animal species. In conclusion, our results con firmed the higher discriminatory power of spoligotyping in relation to that of RFLP analysis for the differentiation of M. bovis genomic profiles. Our data showed the presence of a common M. bovis genotype in both cattle and wild boars, confirming the possible interspecies transmission of M. bovis.