Unique genotypes of Mycobacterium avium subsp. paratuberculosis strains of Type III

Area of Science:

• Veterinary Microbiology
• Genomics
• Bacterial Pathogenesis

Background:

• Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's disease in ruminants.
• MAP strains are traditionally classified into Type I (human/wildlife), Type II (bovine), and a less defined Type III group.
• Understanding MAP genomic diversity is crucial for disease control and host association studies.

Purpose of the Study:

• To characterize novel MAP isolates from migrating sheep in Germany.
• To investigate the genomic diversity of MAP in relation to host, geography, and existing classification schemes.
• To determine the phylogenetic relationship of these novel strains within the MAP subspecies.

Main Methods:

• IS900 restriction fragment length polymorphism (RFLP) with multiple enzymes (BstEII, PstI, PvuII, BamHI).
• Genomic analysis using gyrB-PCR-restriction endonuclease analysis (PCR/REA), mycobacterial interspersed repetitive unit (MIRU)-PCR, and multilocus short sequence repeat (MLSSR) sequencing.
• IS1311-PCR/REA, IS1311 sequencing, and Large Sequence Polymorphism analysis (LSP).

Main Results:

• Two novel MAP strains from German sheep displayed unique IS900-RFLP patterns distinct from known types.
• Genotyping via gyrB-PCR/REA, MIRU-PCR, and MLSSR confirmed unique genetic profiles, differentiating them from Type I and Type II MAP.
• IS1311-based analyses and LSP supported their placement within the Type III group, distinct from Type II.
• Distinct growth characteristics and unique genotypes were observed within the Type III group.

Conclusions:

• The studied sheep MAP strains represent a distinct Type III group with unique genotypes.
• These findings suggest greater genetic diversity within the MAP Type III group.
• The results indicate that MAP Type I and Type III groups are more closely related to each other than to the bovine Type II group.