“
“Background The aetiologic agent of Johne’s disease or paratuberculosis, M. avium subsp. paratuberculosis (Map), CP868596 is one of the subspecies included in the Mycobacterium avium Complex (MAC). Based on the comparison of whole-genomes of Map, a biphasic evolution scheme has been proposed distinguishing two major lineages, a sheep lineage and a cattle lineage [1]. In addition to genotypic differences [2, 3], PI3K inhibitor strains belonging to these two lineages exhibit phenotypic differences
including growth rate [2–4], utilization of different iron metabolic pathways [4], profile of cytokine responses induced in bovine macrophages [5] or transcriptional profiles in a human macrophage model [6]. The association of each lineage with either the sheep or cattle host is not exclusive since strains representative of either lineage can cause disease in all types of ruminants. Historically, strains belonging to the sheep lineage have been referred to as ‘Sheep or S-type’ and those of the cattle lineage ‘Cattle or C-type’ according to the species from which they were first isolated. As the technologies for molecular typing advanced and more genotyping studies were undertaken, greater genetic diversity
was detected within both the S- and C-type strains. Pulsed-field gel electrophoresis (PFGE) Fludarabine cost revealed three strain types designated Types I, II and III [7, 8]. Type II is synonymous with C-type and types I and III comprise the S-type. In this paper we will use the term S-type to describe collectively type I and III strains and have designated the types I and III as subtypes. S-type strains have not been characterized to
the same extent as C-type strains due to the difficulty in culturing the strains in vitro resulting in a limited number of strains available for such studies. Here we undertook the first comprehensive genotyping study of a large representative panel of S-type strains using various typing methods that have been applied to Map strains, individually or in combinations, to draw a portrait of S-type strains. We studied both inter and intra-subtype genotypic strain differences using restriction fragment length polymorphism analysis coupled with hybridization to IS900 (IS900 RFLP), PFGE and various PCRs based on variable-number tandem repeat (VNTR) loci and mycobacterial interspersed BCKDHA repetitive units (MIRUs) [9, 10] MIRU-VNTR typing [11], the presence or absence of large sequence polymorphisms (LSPs) [12] and the gyrA and B genes [13]. Our panel of S-type strains comprised strains from different geographic origins with different restriction enzyme profiles and includes pigmented strains. We also incorporated typing data obtained for additional Map C-type isolates to represent the all diversity of the genotypes described and Mycobacterium. avium subsp. avium (Maa) Mycobacterium. avium subsp. silvaticum (Mas) and Mycobacterium avium subsp. hominissuis (Mah) for comparison.