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Differentiation of the strains of map in relation to host species and country of origin and identification of host specific strains of map

A panel of 122 isolates of Mycobacterium avium subsp. paratuberculosis (Map) was typed by Amplified Fragment Length Polymorphism (AFLP), Restriction Fragment Length Polymorphism analysis followed by hybridization to IS900 (IS900-RFLP) and Pulsed-Field Gel Electrophoresis (PFGE). Eighty seven isolates were successfully typed by IS900-RFLP using both Bst EII and Pst I enzymes and 79 isolates by PFGE using both Sna BI and Spe I enzymes. Sixty-eight strains were typed by AFLP but due to the variability and reproducibility of the technique, further typing was considered pointless. Partial typing data was obtained for the remaining isolates.

Of the 87 isolates typed by IS900-RFLP, 10 Bst EII - Pst I multiplex profiles were detected. The IS900-RFLP multiplex profile with the widest geographical distribution was B-C1 and the multiplex profile with the broadest host range was B-C17 in this cohort of isolates. The profile B-C17 was only identified in Scotland. Of the 79 isolates typed by PFGE, 18 Sna BI-Spe I multiplex PFGE profiles were detected. The PFGE multiplex profile with the widest geographical distribution was [2-1] and this multiplex profile also had the broadest host range.

These results concurred with the typing results obtained in project QLRT-2000-01420. It was not possible to sub-group the Map isolates by AFLP due to the combination of low genotypic diversity and experimental variation inherent in this technique.

Map was isolated from the following wildlife species: fallow deer, red deer, moufflon, badger, fox, stoat, weasel, crow, rook, jackdaw, hare, rabbit, rat and wood mouse. A number of profiles were associated with a single host species but the number of isolates with the profiles in question were too small to make any comment regarding the existence of host species specific strains.

AFLP typing revealed what may be a goat-specific genotype polymorphism but this result requires further investigation. It was difficult to make any conclusions from the results regarding the transmission of Map between wildlife and domestic livestock. The same strain types could be found in both domestic ruminants and wildlife (IS900-RFLP types B-C1, B-C17 and B-C9; PFGE types [2-1], [1-1] and [2-30]), which were also the most prevalent. In the panel of isolates examined, there were few examples of wildlife and domestic ruminant isolates obtained from the same property. In the Czech Republic isolates from a hare and a cow were made on the same property but were shown to have different IS900-RFLP types. In Scotland, isolates from a cow, stoat and rat were found to have the same PFGE-type on property GE, and isolates from a cow, stoat, rook, rabbit and hare were found to have the same PFGE type on property EN.

Analysis of the results showed that it was not uncommon for more than one strain of Map to be isolated from animals on a single property.

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