Identification of group VS116 strains among Borrelia burgdorferi sensu lato grown from the hard tick, Ixodes ricinus (Linnaeus, 1758) by off-coupled restriction fragment length polymorphism analysis.

A total of 67 spirochetal isolates grown from the hard tick, Ixodes ricinus were analysed by PCR amplification of the spacer region between two conserved structures, the 3' end of the 5S rRNA and the 5' end of the 23S rRNA genes of Borrelia burgdorferi sensu lato. A 246-255 bp amplicon was generated from 13 reference strains of B. burgdorferi sensu lato representing the three major genospecies, B. burgdorferi sensu stricto, B. garinii, and B. afzelii, and from all 67 spirochetal isolates from ticks but not from B. hermsii. As could be confirmed by DNA sequence analysis, restriction fragment length polymorphism (RFLP) analysis of the PCR product after cleavage with DraI and MseI distinguished between the three major genospecies: out of the 67 B. burgdorferi sensu lato isolates from ticks, 27 (40.3%) were typed as B. burgdorferi sensu stricto including five isolates with a unique DraI or MseI pattern. 26 isolates (38.8%) were typed as B. garinii and 6 (9.0%) as B. afzelii, respectively. A group of eight isolates (11.9%) displayed a unique MseI pattern identical to that described for a putative new European genospecies of Borrelia burgdorferi sensu lato designated VS116. DNA sequences of the PCR product of seven of these isolates tested were by less than 88.5% identical with the established European major genospecies but shared 98% to 100% homology with that of database-derived sequences of strain VS116 from Switzerland and strain UK from England which are both representatives of the European genomic group VS116.