Publications

3846

“Candidatus Liberibacter europaeus” (Leu) is one of six currently known Liberibacter species. It is known primarily from pear and related species across Europe, and from Scotch broom and its associated psyllids in New Zealand (introduced from Britain). The psyllids were introduced to New Zealand as a biocontrol agent for broom and it is thought the bacterium may have been introduced as an endosymbiont of the psyllids. No symptoms in apple or pear trees have been reported, but mild symptoms can occur in broom. 16S and 16S–23S intergenic spacer region DNA sequences of this species are available from GenBank. Analysis of these sequences and associated ecological descriptions indicates the occurrence of two haplotypes, LeuA and LeuB, defined not only genetically but also by geographic range as well as by plant/psyllid host species composition. Liberibacter species are new to science and haplotype identifications enable historical accounts of relationships and spread to be generated.

“CandidatusNeoehrlichia mikurensis” is the tick-borne agent of neoehrlichiosis, an infectious disease that primarily affects immunocompromised patients. So far, the genetic variability of “Ca. Neoehrlichia” has been studied only by comparing 16S rRNA genes andgroELoperon sequences. We describe the development and use of a multilocus sequence analysis (MLSA) protocol to characterize the genetic diversity of clinical “Ca. Neoehrlichia” strains in Europe and their relatedness to other species within theAnaplasmataceaefamily. Six genes were selected:ftsZ,clpB,gatB,lipA,groEL, and 16S rRNA. Each MLSA locus was amplified by real-time PCR, and the PCR products were sequenced. Phylogenetic trees of MLSA locus relatedness were constructed from aligned sequences. Blood samples from 12 patients with confirmed “Ca. Neoehrlichia” infection from Sweden (n= 9), the Czech Republic (n= 2), and Germany (n= 1) were analyzed with the MLSA protocol. Three of the Swedish strains exhibited identicallipAsequences, while thelipAsequences of the strains from the other nine patients were identical to each other. One of the Czech strains had one differing nucleotide in theclpBsequence from the sequences of the other 11 strains. All 12 strains had identical sequences for the genes 16S rRNA,ftsZ,gatB, andgroEL. According to the MLSA, among theAnaplasmataceae, “Ca. Neoehrlichia” is most closely related toEhrlichia ruminantium, less so toAnaplasma phagocytophilum, and least toWolbachiaendosymbionts. To conclude, three sequence types of infectious “Ca. Neoehrlichia” were identified: one in the west of Sweden, one in the Czech Republic, and one spread throughout Europe.