B.N. Tripathi

Mycobacterium avium subsp. paratuberculosis invades through M cells and enterocytes across ileal and jejunal mucosa of lambs

Mechanism of Mycobacterium avium subsp. paratuberculosis (Map) invasion through intestinal mucosa is not completely understood. In the present study, we developed an in vivo multiple-intestinal loop model in lambs to investigate (i) the type of cells involved in the bacterial uptake across the intestinal mucosa, (ii) the efficiency of bacterial uptake in different segments of the small intestine and (iii) the ability of different strains of Map to invade the various segments of the small intestine. Four loops on ileum and four loops each on Peyers patch and non-Peyers patch areas of jejunum were constructed by surgical procedure. The caprine, bovine, and vaccine strains of Map were used for infection. Map-infected intestinal loop tissues were collected at 1, 3, 6, 12, and 24 h post-infection and processed for electron microscopy, histology, bacterial culture and bacterial counting. All these parameters revealed that Map invaded through M cells and the enterocytes and bacterial translocation across M cells was greater than the enterocytes. Bacterial invasion was greater in ileal loops when compared to jejunal loops. Within the jejunal loops, bacterial uptake was higher in Peyers patch areas than that of non-Peyers patch areas. The caprine and bovine strains of Map showed greater ability for invasion into the small intestinal mucosa than that of the vaccine strain.

Studies on pathology, cytokine gene expression and molecular typing of Mycobacterium avium subsp. paratuberculosis of naturally occurring Johne's disease in bullocks

Pathology of Johnes disease (JD) in bullocks (castrated, adult male cattle) is rarely studied. Here, we report the pathology and cytokine gene expression of naturally occurring JD in bullocks. The small intestine and mesenteric lymph nodes collected from 404 bullocks, aged between 5 and 10years, were examined for JD lesions and detection of Mycobacterium avium subsp. paratuberculosis (Map). A total of 8.7% bullocks exhibited JD lesions, which were classified into multibacillary-diffuse granulomatous (n=2), paucibacillary-focal granulomatous (n=18) and paucibacillary-diffuse lymphocytic (n=15) lesions. The tissue cytokine gene expression profiles in all three forms of lesions corroborated with different immuno-pathological processes of JD in bullocks. The molecular typing and gene sequencing identified Map isolates from bullocks as bison type.