BackgroundWhole genome sequencing allowed the development of a number of high resolution sequence based typing tools for Yersinia (Y.) pestis. The application of these methods on isolates from most known foci worldwide and in particular from China and the Former Soviet Union has dramatically improved our understanding of the population structure of this species. In the current view, Y. pestis including the non or moderate human pathogen Y. pestis subspecies microtus emerged from Yersinia pseudotuberculosis about 2,600 to 28,600 years ago in central Asia. The majority of central Asia natural foci have been investigated. However these investigations included only few strains from Mongolia.Methodology/Principal FindingsClustered Regularly Interspaced Short Prokaryotic Repeats (CRISPR) analysis and Multiple-locus variable number of tandem repeats (VNTR) analysis (MLVA) with 25 loci was performed on 100 Y. pestis strains, isolated from 37 sampling areas in Mongolia. The resulting data were compared with previously published data from more than 500 plague strains, 130 of which had also been previously genotyped by single nucleotide polymorphism (SNP) analysis. The comparison revealed six main clusters including the three microtus biovars Ulegeica, Altaica, and Xilingolensis. The largest cluster comprises 78 isolates, with unique and new genotypes seen so far in Mongolia only. Typing of selected isolates by key SNPs was used to robustly assign the corresponding clusters to previously defined SNP branches.Conclusions/SignificanceWe show that Mongolia hosts the most recent microtus clade (Ulegeica). Interestingly no representatives of the ancestral Y. pestis subspecies pestis nodes previously identified in North-western China were identified in this study. This observation suggests that the subsequent evolution steps within Y. pestis pestis did not occur in Mongolia. Rather, Mongolia was most likely re-colonized by more recent clades coming back from China contemporary of the black death pandemic, or more recently in the past 600 years.
Tick-borne encephalitis virus (TBEV) causes one of the most important inflammatory diseases of the central nervous system, namely severe encephalitis in Europe and Asia. Since the 1980s tick-borne encephalitis is known in Mongolia with increasing numbers of human cases reported during the last years. So far, however, data on TBEV strains are still sparse. We herein report the isolation of a TBEV strain from Ixodes persulcatus ticks collected in Mongolia in 2010. Phylogenetic analysis of the E-gene classified this isolate as Siberian subtype of TBEV. The Mongolian TBEV strain showed differences in virus titers, plaque sizes, and growth properties in two human neuronal cell-lines. In addition, the 10,242 nucleotide long open-reading frame and the corresponding polyprotein sequence were revealed. The isolate grouped in the genetic subclade of the Siberian subtype. The strain Zausaev (AF527415) and Vasilchenko (AF069066) had 97 and 94 % identity on the nucleotide level. In summary, we herein describe first detailed data regarding TBEV from Mongolia. Further investigations of TBEV in Mongolia and adjacent areas are needed to understand the intricate dispersal of this virus.
Although Mongolia is regarded as one of the possible places of plague radiation, only few data are available from Mongolian Yersinia pestis strains. In this study a total of 100 Mongolian Y. pestis strains isolated from wild mammals and their parasites between the years 1960 and 2007 were analyzed for their phenotype. All strains grew well on selective Cefsulodin-Irgasan-Novobiocin agar and were positive for the F1-antigen, the F1-gene (caf1), and the plasminogen activator gene (pla). Biochemical analyses using the API20E® system identified 93% of the strains correctly as Y. pestis. The BWY in-house system consisting of 38 biochemical reactions was used to differentiate among Y. pestis subspecies pestis biovars Antiqua and Medievalis and also between the subspecies microtus biovars Ulegeica and Caucasica. Antibiotic susceptibility testing according to Clinical and Laboratory Standards Institute-guidelines identified one strain as being multiresistant. This strain was isolated from a wildlife rodent with no anthropogenic influence and thus suggests naturally acquired resistance.
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