First Insight into the Whole Genome Sequencing Whole Variations in Mycobacterium bovis from Cattle in Morocco

Abstract

Six cattle heads which tested positive against bovine tuberculosis (bTB) in Morocco were investigated to confirm the disease and to determine the source(s) of infection. Polymerase Chain Reaction (PCR) was directly performed on tissue samples collected from slaughtered animals. All investigated animals tested positive to PCR for the Mycobacterium bovis sub-type. Bacteriological isolation was conducted according to the technique recommended by WOAH for the cultivation of the Mycobacterium tuberculosis Complex (MBTC). Whole genome sequencing (WGS) was carried out on six mycobacterial isolates and the phylogenic tree was constructed. The six Moroccan isolates fit with clades II, III, IV, V and VII and were confirmed to belong to the clonal complexes Eu2, Unknown 2 and 7 as well as to sublineages La1.7.1, La1.2 and La1.8.2. The significant Single Nucleotide Polymorphism (SNPs) ranged from 84 to 117 between the isolates and the reference M. bovis strain and from 17 to 212 between the six isolates. Considering the high resolution of WGS, these results suggests that the source of infection of the bTB could be linked to imported animals as five of the investigated reactor animals were imported a few months prior. WGS can be a useful component to the Moroccan strategy to control bTB.