Specific immunoassays confirm association of Mycobacterium avium Subsp. paratuberculosis with type-1 but not type-2 diabetes mellitus

Background: Mycobacterium avium subspecies paratuberculosis (MAP) is a versatile pathogen with a broad host range. Its
association with type-1 diabetes mellitus (T1DM) has been recently proposed. Rapid identification of infectious agents such
as MAP in diabetic patients at the level of clinics might be helpful in deciphering the role of chronic bacterial infection in the
development of autoimmune diseases such as T1DM.
Methodology/Principal Findings: We describe use of an ELISA method to identify live circulating MAP through the
detection of a cell envelope protein, MptD by a specific M13 phage – fMptD. We also used another ELISA format to detect
immune response to MptD peptide. Both the methods were tested with blood plasma obtained from T1DM, type-2 diabetes
(T2DM) patients and non-diabetic controls. Our results demonstrate MptD and fMptD ELISA assays to be accurate and
sensitive to detect MAP bacilli in a large fraction (47.3%) of T1DM patients as compared to non-diabetic controls (12.6%) and
those with confirmed T2DM (7.7%). Comparative analysis of ELISA assays performed here with 3 other MAP antigen
preparations, namely HbHA, Gsd and whole cell MAP lysates confirmed comparable sensitivity of the MptD peptide and the
fMptD based ELISA assays. Moreover, we were successful in demonstrating positive bacterial culture in two of the clinical
specimen derived from T1DM patients.
Conclusions and Significance: The MptD peptide/fMptD based ELISA or similar tests could be suggested as rapid and
specific field level diagnostic tests for the identification of MAP in diabetic patients and for finding the explanations towards
the occurrence of type-1 or type-2 diabetes in the light of an active infectious trigger.