Is Mycobacterium avium subsp. paratuberculosis, the cause of Johne’s disease in animals, a good candidate for Crohn’s disease in man.

Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne’s disease or paratuberculosis, a gastro intestinal inflammatory condition in ruminants and other animals, which is similar to Crohn’s disease (CD) that occurs in man. The role of MAP in the causation of CD has been under intense investigation in the last few decades. This review summarizes the status of MAP in animals and the food chain and its association with CD in man.

Strain diversity within Mycobacterium avium subspecies paratuberculosis — A review.

Mycobacterium avium subspecies paratuberculosis (MAP), is the etiological agent of Johne’s disease (or paratuberculosis) in animals and has also been linked with Crohn’s disease of human beings. Extreme fastidious nature of the organism (MAP) has hampered studies on diversity within the organism. Studies based on phenotypic properties like growth rate, pigmentation, lipid profile etc., are unable to provide complete information on diversity of MAP organism in nature. However, with the advent of molecular assays (IS900 RFLP, PFGE, IS1311 PCR-REA, SSR typing, VNTR typing etc.) in last 2 decades, progress has been made to differentiate MAP strains. MAP isolates have been classified into various types and subtypes using these molecular tools. Optimization of these typing assays has led to generation of new information about MAP strains, subtypes, their comparative genomics, relative evolution, comparative virulence etc. Knowledge of strain diversity is important for better understanding of molecular and sero-epidemiology, infection and patho-biology, vaccine development and planning control strategies. The present review provides available information on MAP strains, host adaptations, their virulence, comparative genomics, relative genetic evolution and differentiation.

Evaluation of four methods of DNA recovery from Mycobacterium avium subspecies paratuberculosis present in intestine tissue of goats and comparative sensitivity of IS900 PCR with respect to culture for diagnosis of Johne's disease.

Low sensitivity of PCR reaction for detection of Mycoobacterium avium subspecies paratuberculosis (MAP) in tissues and fecal samples is mainly attributed to false negative results. Present study was undertaken to compare four methods of DNA isolation from tissues of infected animals and to determine most sensitive protocol for the recovery of DNA, suitable for IS900 PCR based detection of Johne's disease infection. Method I, the traditional van Soolingen2 method of DNA isolation was adopted for the isolation of DNA from tissues. Method II was modification (hexadecyl pyridinium chloride-HPC treatment) of van Soolingen2 method. Method III was traditional tissue DNA isolation method based on tissue lysis buffer. Method IV was modification of method III (HPC treatment). Using four methods of DNA isolation from 25 intestinal tissues of clinically infected goats, DNA was isolated from 15 (60.0%), 18 (72.0%), 13 (52.0%) and 13 (52.0%) tissues using method I, II, III and IV, respectively. All isolated DNA preparations were positive for MAP in IS900 PCR. HPC treatment enhanced the recovery of DNA from tissues of infected animals using method II. Therefore, method II can improve the diagnosis MAP infection using IS900 PCR.

Mycobacterium avium subspecies paratuberculosis diagnosis and strain typing--present status and future developments.

Mycobacterium avium subspecies paratuberculosis (MAP) is the etiological agent of paratuberculosis, a chronic gastroenteritis of ruminants and has zoonotic importance. We present here a review of MAP with respect to--(i) present diagnostic techniques and important developments; and (ii) MAP strain-typing tools. A summary of the findings to date is presented, and advantages and disadvantages of each of the methods are compared and discussed.

Non-chemical method of DNA recovery and characterization of Mycobacterium avium subspecies paratuberculosis using IS 900 PCR.

In the present study, two methods of DNA isolation-routine, traditional and standard DNA isolation protocol for Mycobacteria (Method 1) and a new non-chemicals and non-enzymes (physical) method (Method 2) of DNA recovery have been compared and evaluated in IS900 PCR for the specific detection of pathogen. Using the new Method 2, DNA has been recovered from few (1 - 3 colonies), extremely minute and stunted colonies. DNA, thus, isolated from these colonies (colonies PCR) and cultured for the first time from the cases of Crohn's disease in human beings, dairy cattle, raw milk and pasteurized commercial milk samples has been characterized in the present study. It is the first report from India.