Advantages of Real-time PCR and RD4-PCR as Molecular Methods for Rapid Detection of Bovine Tuberculosis in Bulgaria

Abstract

Representatives of Mycobacterium tuberculosis complex (MTBC) are potential causative agents of tuberculosis in animals and humans, and Mycobacterium bovis is considered a major one among domestic and wild ruminants. In the last twenty years, the role of another representative of MTBC – Mycobacterium caprae, has been proven in the countries of Central and Southern Europe. Study sample included 121 diagnostic materials from lymph nodes and lungs from cattle, positively and doubtfully PPD tuberculin-reacted, originating from 6 farms belonging to the 4 regions in Northern and Southern Bulgaria. The bacteriological examination showed typical growth for mycobacteria for 110 (90.9%) samples, which was confirmed by qPCR. By RD4-PCR we proved that 102 (92.7%) of the mycobacterial strains were M. caprae and the remaining 8 strains (7.3%) were M. bovis. This defines M. caprae as a dominant species in the etiology of tuberculosis in cattle in Bulgaria. In conclusion, we confirmed that the application of real-time PCR is an accurate and convenient method for rapid detection of M. bovis from cattle in the Bulgarian settings. RD4-PCR provides a sufficiently high differentiation and can be used for first-line typing of M. bovis isolates in Bulgaria. This proves the need for the simultaneous application of both methods in the diagnosis of bovine tuberculosis in Bulgaria.