Mycobacterium bovis and M. caprae in Bulgaria: insight into transmission and phylogeography gained through whole-genome sequencing
BMC Veterinary Research
Oglądaj/ Open
Data
2022Autor
Valcheva, Violeta
Perea, Claudia
Savova‑Lalkovska, Tanya
Dimitrova, Albena
Radulski, Lukasz
Mokrousov, Igor
Marinov, Krustyu
Najdenski, Hristo
Bonovska, Magdalena
Metadane
Pokaż pełny rekordStreszczenie
Background: This study aimed to characterize recent Mycobacterium bovis/M. caprae isolates from Bulgaria by whole‑
genome sequencing (WGS) to gain a first insight into their molecular diversity, transmission, and position within the
global phylogeography of this important zoonotic species.
Results: The isolates were obtained from cattle in diverse locations of Bulgaria in 2015‑2020 and were identified
by microbiological and PCR assays. WGS data were used for phylogenetic analysis that also included M. bovis global
dataset. Thirty‑seven M. bovis/caprae isolates from Bulgaria were studied and 34 of them were SNP genotyped. The
isolates were subdivided into 3 major phylogenetic groups. Type Mbovis‑13 (Eu2 complex [western Europe and north‑
ern Africa]) included one isolate. Mbovis‑37 type included 5 isolates outside of known clonal complexes. The Bulgar‑
ian M. caprae isolates formed a sub‑group within the Mcaprae‑27B cluster which also included 22 M. caprae isolates
from Poland, Spain, Germany, and the Republic of Congo. The Bulgarian M. caprae isolates share their latest common
ancestors with Spanish isolates. The Mbovis‑37 group shares a distant common ancestor (pairwise distance 22‑29
SNPs) with an isolate from Poland but was very distant (> 200 SNPs) from the rest of the tree. The Mbovis‑13 group
shares a common ancestor with two human isolates from Germany. Phylogeographically, both M. bovis clades had
limited circulation in northeastern Bulgaria while the majority of the studied isolates (M. caprae) were from central and
western provinces. A phylogenetic network‑based analysis demonstrated that 11 Bulgarian isolates were separated by
1 to 6 SNPs within four clusters, mostly forming pairs of isolates.
Conclusion: The obtained WGS analysis positioned the Bulgarian isolates within the global phylogeography of
M. bovis/M. caprae. Hypothetically, the observed phylogenetic diversity may not have resulted from livestock trade
routes, but instead may reflect the deeply rooted M. bovis/M. caprae phylogeography of Europe. A high level of
genetic divergence between the majority of the studied isolates suggests limited active transmission of bTB in Bul‑
garia during the survey period. At the same time, a possibility of the endemic presence of circulating bTB strains in the
form of the latent persistent disease cannot be ruled out.
Zbiory
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