Babesia microti-Like Parasites Detected in Eurasian Red Squirrels (Sciurus vulgaris orientis) in Hokkaido, Japan

Abstract

ABSTRACT. Six Eurasian red squirrels (Sciurus vulgaris orientis), victims of road traffic found during 2002 and 2004 near the Noppro Forest Park in Ebetsu, Hokkaido, Japan, were examined for the presence of Babesia parasites. Three of the six squirrels exhibited positive signals by nested PCRs targeting both the 18S rRNA and β-tubulin genes. Three squirrels proved to be infected with a B. microti-like parasite as evidenced by sequencing the amplified DNAs and by the morphology of the intraerythrocytic parasites. Genotypically, however, the parasite appeared to be of a new type, as it was clearly distinguishable from any of the known types that have previously been reported in various wild animals. This is the first report showing molecular evidence for the presence of B. microti-like parasites in Sciuridae.

Babesia microti-Group Parasites Compared Phylogenetically by Complete Sequencing of the CCT.ETA. Gene in 36 Isolates

“…Taken together, the introns and phylogenetic trees in the present study not only reinforce the intragroup tri-classification proposed previously (U.S., Kobe, Hobetsu) [37,38,43,44] but, more important, identify Munich as a fourth distinctive group making up the B. microti complex. This finding is in keeping with suspicions raised by 18S rDNA [11,26,32] and β-tubulin [37] gene sequencing analyses, but the CCTη gene adds a new dimension dramatically expanding and enriching the work achieved so far. Surprisingly, in the CCTη gene sequences the 5 Munich isolates had 100% identity among themselves (intra-Munich) in spite of having geographically diverse origins (UK, Poland and Germany), but they had negligible identity with the U.S. (88.9%), Kobe (83.2%) and Hobetsu (85.1%) parasites (Table 3).…”

“…This capability makes the gene especially reliable and useful for phylogenetic analysis. While informed by valuable studies relying on 18S rDNA and the β-tubulin gene [8,9,26,30,32,37,38,41,43,44], if we are to identify the true character of the infectious agent B. microti and separate the "related" but noninfectious culprits, then the research arsenal must make use of additional genes such as CCTη in the target parasites.…”

“…One isolate each from 2 ticks (I. ricinus) captured in Poland (Poland5, Poland6) and one each from 2 bank voles (C. glareolus) captured in the UK (UK5, UK6), donated by Marek Sawczuk and Bogumila Skotarczak (Szczecin University, Poland) and Mitsuhiko Asakawa (Rakuno Gakuen University, Japan), respectively, had a β-tubulin gene sequence identical to that of the Munich strain (GenBank accession number AB124587); hence, we included those 4 isolates in this analysis of the B. microti group. Other isolates were taken from raccoons and Eurasian red squirrels in Japan [15,37].…”

“…Accordingly, multiple clusters, or clades, also branched from the β-tubulin trees constructed in our laboratory, viz., the U.S., Kobe, and Hobetsu genotypes, and most of the B. microti-like parasites isolated from rodents in Japan, Korea, Far East Russia and northwestern China fell into one of these three genotypes [43,44]. Cluster distinctions described by the two research teams, however, showed inconsistency in certain aspects, probably owing to the sampling deviations; the parasites in the respective studies were obtained mostly from North America [8] or Northeast Asia [37,43,44]. Today, with escalating recruitment of new genotypes from widespread geographic regions and a multiplicity of wild mammalian hosts, evidence of intra-group genetic diversity is accruing.…”

Detection of Two Zoonotic Babesia microti Lineages, the Hobetsu and U.S. Lineages, in Two Sympatric Tick Species, Ixodes ovatus and Ixodes persulcatus, Respectively, in Japan

“…Other taxa, such as the Munich taxon in Europe and B. microti in Alaskan voles, are believed to be maintained only in wild animals. All of these lineages are found naturally parasitizing a variety of wild mammalian species in the rodent subfamilies of the Murinae, Arvicolinae, and Sigmodontinae and, occasionally, in the Soricidae shrew (9,11,12,26,30,32,34,37,38).…”