Abstract
BackgroundBoth bovine tuberculosis (TB) and paratuberculosis (PTB) are serious and widespread bacterial infections affecting many domestic and wild animal species. However, current vaccines do not confer complete protection and cause interference with other diagnostics tests, including bovine TB. Therefore, the development of “Differentiating Infected from Vaccinated Animals” (DIVA) tests are a pressing need. In this study, we have tested the feasibility of mycobacterial extracellular vesicles (EVs) as potential source of biomarkers to discriminate between Mycobacterium bovis infected, Mycobacterium avium subsp. paratuberculosis (MAP) infected and MAP-vaccinated cows. We have, initially, characterized vesicle production in the two most medically relevant species of mycobacteria for livestock, MAP and M. bovis, for being responsible for tuberculosis (TB) and paratuberculosis (PTB).ResultsOur results indicate that these two species produce EVs with different kinetics, morphology and size distribution. Analysis of the immunogenicity of both type of EVs showed some cross reactivity with sera from PTB+ and TB+ cows, suggesting a limited diagnostic capacity for both EVs. Conversely, we noticed that Mycobacterium tuberculosis (Mtb) EVs showed some differential reactivity between sera from MAP-vaccinated or PTB+ cows from TB+ ones. Mass spectrometry analysis (MS) identified a 19-kDa EV-associated lipoprotein as the main source of the differential reactivity.ConclusionsLpqH could be a good plasma biomarker with capacity to distinguish PTB+ or MAP-vaccinated cows from cows infected with TB.
Highlights
Both bovine tuberculosis (TB) and paratuberculosis (PTB) are serious and widespread bacterial infections affecting many domestic and wild animal species
Characterization of M. bovis and Mycobacterium avium subsp. paratuberculosis (MAP) Extracelular vesicle (EV) We have previously shown the conservation of EV production in the Mycobacterium genus [7]
We show in more detail isolated EVs from two of the most relevant mycobacterial species affecting both domestic animals and wildlife, including M. bovis and M. avium subsp. paratuberculosis (MAP)
Summary
We have characterized vesicle production in the two most medically relevant species of mycobacteria for livestock, MAP and M. bovis, for being responsible for tuberculosis (TB) and paratuberculosis (PTB). Both bovine tuberculosis (TB) and paratuberculosis (PTB) are serious and widespread bacterial infections affecting many domestic and wild animal species. We had demonstrated that Mtb and BCG EVs are enriched in lipoproteins [7] that can reach the extracellular space independently of host-derived exosome production in Mtb-infected macrophages [9], suggesting that they could be circulating in the infected host as separate entities This scenario suggests that mycobacterial EVs could represent good biomarkers for disease. Considering the limitation of current diagnostic tools in PTB and bovine TB+, we reasoned that it was worthwhile to investigate the biomarker potential of mycobacterial EVs in the contexts of these two diseases
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