Morphological and Molecular Characterization of a New Mycobacterium avium Subsp. paratuberculosis S-Type Strain Genotype in Goats.

Simone Scherrer,Roger Stephan,Anja Kipar,Frauke Seehusen,Jon Paulin Zumthor

doi:10.3389/fvets.2019.00250

Abstract

Paratuberculosis is a chronic bacterial disease of global importance mainly in domestic and wild ruminants, caused by Mycobacterium avium subsp. paratuberculosis (MAP). In goats, paratuberculosis is mostly caused by the “C-type” (cattle) and in a few cases by the “S-type” (sheep) strain of MAP. In 2017, a caprine S-type III isolate with a new VNTR profile was identified in a Swiss alpine region. In 2018, new caprine isolates with the same novel VNTR profile originating from a farm of a close by neighboring valley were analyzed. Here we report on this MAP S-type III outbreak in a Swiss dairy goat farm in which we investigated the pathological changes, distribution and genotype of MAP tissue homogenates. Full necropsy and histological examination were undertaken on two female adult goats with a history of weight loss and intermitting diarrhea. Routine and special stains were applied to characterize the morphological changes. DNA was extracted from 33 different tissue samples and tested for MAP by qPCR targeting IS900 and F57. Subtyping was performed, using the variable number tandem repeats (VNTR) and mycobacterial interspersed repetitive units (MIRU) approach. The goats showed moderate to marked emaciation and displayed typical clinical features of paratuberculosis. A moderate granulomatous enteritis and regional lymphadenitis with a small to moderate number of acid-fast bacteria within macrophages was detected. MAP detection was mainly restricted to the gastrointestinal tract, mesenteric and hepatic lymph nodes. Subtyping the S-type isolates using a panel of eight established MIRU-VNTR loci identified a new genotype, INMV 218.

Highlights

Paratuberculosis or Johne’s disease is characterized by a chronic progressive granulomatous enteritis caused by the pathogen Mycobacterium avium subsp. paratuberculosis (MAP)
The present study reports paratuberculosis caused by a new genotype in two goats from a Swiss dairy farm
The pathological features in both animals were consistent with those generally observed with paratuberculosis in small ruminants, comprising a granulomatous inflammation in small intestines and mesenteric lymph nodes [25]

Summary

Introduction

Paratuberculosis or Johne’s disease is characterized by a chronic progressive granulomatous enteritis caused by the pathogen Mycobacterium avium subsp. paratuberculosis (MAP). The usual route of MAP infection is fecal-oral, with. Based on its association with host species, MAP has been allocated to two major groups, the “Sheep-type” ( called “S-type” or “type I and III”) and the “Cattle-type” ( called “C-type” or “type II”) [4, 5]. Goats with paratuberculosis are infected by C-type MAP, S-type infections of goats are not rare and have been described previously [6]. In contrast to the C-type strains, S-type MAP grow much slower and more fastidious in culture media [9, 10]. C-type MAP has a higher infection ability and better surviving capacity in macrophages compared to S-type MAP [11]

Methods

Results

Conclusion