Comparison of IS900 PCR with ‘Taqman probe PCR’ and ‘SYBR green Real time PCR’ assays in patients suffering with thyroid disorder and sero-positive for Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis (MAP) is the cause of chronic incurable granulomatous enteritis in domestic livestock and has been associated with number of human autoimmune disorders like thyroiditis. Indigenous ELISA kit was used to monitor the sero-status of MAP infection in the patients of thyroiditis confirmed by pathology laboratories using 3rd generation chemi-luminescent assays. Sero-positive patients for MAP infection were further investigated using traditional PCR and newer (Taqman probe PCR & SYBR green Real time PCR) assays targeting IS900 gene. Screening of 76 patients suffering with thyroid disorders, 36.8% (n=28) were sero-positive for MAP infection. Further screening of blood samples of 28 sero-positive patients by IS900 PCR, Taqman probe and SYBR green Real time based IS900 PCR, 25.0, 32.1 and 35.7% were positive for MAP infection, respectively. Molecular assays targeting IS900 gene revealed ‘good agreement’ in the tests. Taqman probe and SYBR green Real time based IS900 PCR assays were 100.0 and 85.7% sensitive, respectively and highly specific as compared to IS900 PCR for the detecting MAP infection. Study indicated the need for investigating the role of MAP in initiation and progression of thyroid disorders and on the genetic susceptibility of thyroid patients to MAP infection. In the absence of control programmes in the domestic livestock population, there is large scale exposure of human population to MAP infection.