Applicability of using 15 MIRU-VNTR loci for genotyping of Mycobacterium avium subsp. paratuberculosis from two cattle farms in Egypt.

Mycobacterium avium subspecies paratuberculosis (MAP) is a notorious infectious agent that causes Johne's disease which leads to serious economic losses in cattle farms all over the world. The Lack of accurate epidemiological and molecular data is a major barrier to the implementation of disease control strategies. Basically, the tracing of infections requires rapid detection of the widely spreading genotypes with the ability to determine isolates from common and different sources. This study aimed to evaluate the applicability and discriminatory power of 15 mycobacterial interspersed repetitive unit (MIRU)-variable number tandem repeat (VNTR) loci of M. tuberculosis for MAP genotyping. Additionally, detection of the most efficient loci combinations for molecular epidemiological investigations of MAP isolates. The discriminatory capacity and applicability of 15 known loci [2 exact tandem repeat (ETR) loci, 6 MIRU loci, 4 Mtub loci, and 3 Queen's University of Belfast (QUB) group loci] were assessed using 26 isolates from two cattle herds (Holstein Frisian) in El buhaira and Giza Governorates at north of Egypt. The results proved the presence of 12 different genotypes. All the used loci gave Hunter-Gaston discrimination index of DI = 0.963 while the ten loci (Mtub04, MIRU10, QUB11b, MIRU26, QUB26, QUB4156, MIRU04, ETRC, Mtub30, and Mtub39) were highly discriminating with DI = 0.956. Moreover, the five loci (Mtub21, MIRU31, MIRU16, MIRU40, and ETRA) gave moderate discriminatory power with DI = 0.839. The MIRU31 locus expressed no polymorphism among strains. MIRU-VNTR typing generally proved applicability and high discriminatory power with DI = 0.963. The ten highly discriminating DI = 0.956 proved to be the most suitable for the first-line genotyping of MAP from cattle, with nearly similar resolving ability as all the 15 loci. MIRU-VNTR proved fastness, efficiency, and feasibility in genotyping of MAP from cattle in Egypt.