Isolation and characterization of Borrelia burgdorferi sensu lato strains in an area of Italy where Lyme borreliosis is endemic

Between 1993 and 1998, we isolated Borrelia burgdorferi sensu late from 55 of the 119 patients with clinically diagnosed Lyme borreliosis who were adm itted to "San Martino" Hospital in Belluno, Veneto, an Adriatic region in n ortheastern Italy where Lyme borreliosis is endemic. Upon hospitalization, all patients presented erythema migrans. Isolates were typed using ribosoma l DNA PCR-restriction fragment length polymorphism (RFLP) analysis of the r rfA-rrlB intergenic spacer. Of the 41 isolates typed, 37 belonged to Borrel ia afzelii, 2 to Borrelia garinii, and 2 to B. burgdorferi sensu stricto. P ulsed-field gel electrophoresis, performed on 21 strains (13 new isolates a nd 8 controls), revealed different RFLP patterns within the B. garinii and B. afzelii strains; among the five B. garinii strains and the 12 B. afzelii strains, three or two different RFLP patterns were identified, according t o the restriction enzyme used. The protein patterns of the new isolates con firmed their genotypic classification and revealed the level of expression of some immunodominant proteins like OspA and other characteristic Osps. Th ese findings constitute the first report of such a high recovery rate of B. burgdorferi from patients in a very restricted area in Italy; they also in dicate the predominance of the genospecies B. afzelii in the study area and the heterogeneity of the circulating strains.