Mycobacterium avium subspecies paratuberculosis diagnosis and geno-typing: genomic insights.

Effective control of paratuberculosis and investigations of potential link to Crohn's disease have been hampered by the lack of effective assays for easy and accurate diagnosis of Mycobacterium avium subspecies paratuberculosis (Map). Map is extremely fastidious and depends on iron chelator (Mycobactin). Map strains from humans and sheep are very difficult to isolate and may require years to emerge. Therefore, small numbers of Map isolates have been maintained in available collections. This situation has limited the study of biodiversity of Map. Though, much is known about environmental and host factors that contribute to paratuberculosis disease, but little is known about bacterial genetic mechanism of infection. Diagnostic and strain typing markers still demand improvements. Complete genome sequence of Map K10 strain is available in public domain for comparative genomics with other mycobacteria and clinical isolates of Map. It is anticipated that the genome sequence will help in carrying molecular diagnosis and strain typing with respect to Map forward at rapid pace. This paper reviews the current diagnostic and strain typing markers, which may be useful in typing of clinical isolates in near future.