SIMULTANEOUS DETECTION AND GENOTYPING OF 3 GENOMIC GROUPS OF BORRELIA-BURGDORFERI SENSU-LATO IN DUTCH IXODES-RICINUS TICKS BY CHARACTERIZATION OF THE AMPLIFIED INTERGENIC SPACER REGION BETWEEN 5S AND 23S RIBOSOMAL-RNA GENES

We developed a rapid and reliable method for the identification Borrel ia burgdorferi sensu lato species in ticks. We used the DNA sequence p olymorphism of the spacer region between 5S and 23S rRNA genes, which has been shown to be able to discriminate between eight genomic groups of B. burgdorferi sensu lato (D. Postic, M. Assous, P. A. D. Grimont, and G. Baranton, Int. J. Syst. Bacteriol. 44:743-752, 1994). Spacer D NA was amplified by PCR and was then hybridized to five membrane-bound oligonucleotides. The oligonucleotides were specific for B. burgdorfe ri sensu stricto, Borrelia garinii, Borrelia afzelii, and group VS116. A probe which reacted with all genomic groups of B. burgdorferi sensu lato was also used. Ninety-six ticks collected in the field were dest ructed by bead beating, and the supernatant was used directly in a PCR . B. burgdorferi sensu lato DNA was detected in 6 of 57 adult ticks (1 1%) and 9 of 39 nymphs (23%). B. garinii was found in three nymphs and four adults, three nymphs carried B. afzelii, and one adult and one n ymph carried group VS116. Double infections with B. afzelii and group VS116 were found in two nymphs and one adult. Thus, our method can sim ultaneously identify three genomic groups of B. burgdorferi sensu lato in ticks collected in the field. This technique provides new ways to study the association of genomic groups present in ticks and the risk of Lyme borreliosis.