Genomic Polymorphisms for Mycobacterium avium subsp. paratuberculosis Diagnostics

Abstract

Mycobacterium avium subsp. paratuberculosis is an emerging pathogen of mammals and is being actively investigated as a possible zoonotic agent. The lack of reliable diagnostic assays has hampered rational assessment of the prevalence of this organism in humans and animals. We have used a comparative genomic approach to reveal genomic differences between M. avium subsp. paratuberculosis and its close relative M. avium subsp. avium, a highly prevalent environmental organism. From computational and DNA microarray-based study of two prototype strains, M. avium subsp. avium strain 104 and M. avium subsp. paratuberculosis strain K10, we have uncovered two types of large sequence polymorphisms (LSPs): those present in the former but missing in the latter (LSP A s) and those only present in the latter (LSP P s). We examined the distribution of 3 LSP A s and 17 LSP P s across a panel of 383 M. avium complex isolates in order to determine their potential utility for the development of accurate diagnostic tests. Our results show that the absence of LSP A 8 is 100% specific for the identification of M. avium subsp. paratuberculosis. Of the 17 LSP P s, 10 regions were not specific for M. avium subsp. paratuberculosis while 7 were shown to be highly specific (>98%) and, in some cases, highly sensitive as well (up to 95%). These data highlight the need to evaluate these regions across a diverse panel of clinical and environmental isolates and indicate the LSPs best suited for M. avium subsp. paratuberculosis diagnostics.Mycobacterium avium subsp. paratuberculosis is a serious pathogen of domestic ruminants, in which it causes paratuberculosis (Johne's disease), a chronic and eventually fatal inflammatory bowel disease. Its rising incidence in many regions of the world has resulted in significant economic losses to the livestock industry (13). This organism also infects free-ranging wildlife species (16). The impact of M. avium subsp. paratuberculosis in nonruminant wildlife species is largely unknown; however, the potential for interspecies transmission has important implications for paratuberculosis control programs. M. avium subsp. paratuberculosis is also being actively investigated as the possible cause of a debilitating human inflammatory bowel disease, Crohn's disease (4, 5, 18).Effective control of Johne's disease and investigation of the potential link to Crohn's disease have been hampered by the lack of effective assays to easily and accurately diagnose M. avium subsp. paratuberculosis infections. Commercially available serological assays for bovine disease are convenient but offer poor sensitivity, especially during subclinical disease. Moreover, owing to the high degree of genetic similarity between M. avium subsp. paratuberculosis and the other members of the M. avium complex, many of the proteins that are recognized during the early stages of infection are not specific for M. avium subsp. paratuberculosis (14). Since M. avium subsp. avium is highly prevalent in the environment but not associated with a similar cli...

Isolation of the Genome Sequence Strain Mycobacterium avium 104 from Multiple Patients over a 17-Year Period

“…The 4 LSPs examined in this study were designated LSP2, LSP7, HSD, and LSPP5. This nomenclature was consistent with prior publications (14,22,23). Each consisted of a genomic region of Ն2.5 kb that was present in some M. avium strains and absent in others.…”

Genomic Comparison of PE and PPE Genes in the Mycobacterium avium Complex

“…This subspecies is a heterogeneous group of strains with at least six distinct hsp65 sequences (hsp65 sequevars) (52). This has previously led to the suggestion that human isolates simply reflect what is found in their environment (44). It will be intriguing to know whether the M. avium subsp.…”

Mycobacterium avium subsp paratuberculosis y enfermedad de Crohn: evidencias de una zoonosis

“…La secuenciación del genoma completo de MAP ha permitido la identifi cación y descripción de diversos marcos de lectura específi cos que se constituyen en potenciales biomarcadores para el diagnóstico de la infección en los hospederos humanos y animales 52,53 . Desde la aplicación del PCR en los estudios de MAP, la secuencia de inserción IS900 ha sido el principal blanco de amplifi cación utilizado, ya que sus 14 a 18 copias en el genoma bacteriano permiten resultados de alta sensibilidad.…”