Diversity of Lyme borreliosis spirochetes isolated from ticks in Serbia

Abstract

Spirochetes from the Borrelia burgdorferi sensu lato (s.l.). (Spirochaetales: Spirochaetaceae) species complex, including the causative agents of Lyme borreliosis, have been isolated from ticks, vertebrate reservoirs and humans. Previous analyses based on direct molecular detection in ticks indicated a considerable diversity of B. burgdorferi s.l. complex in Serbia. The present study aimed (a) to isolate borrelia strains from Serbia; (b) to determine their genotypic characteristics; and (c) to establish a collection of viable B. burgdorferi s.l. strains for further biological, ecological and genetic studies. For the present study, 231 adult Ixodes ricinus (Ixodida: Ixodidae) ticks from 16 ecologically different localities in Serbia were individually processed to cultivate B. burgdorferi s.l. This led to the isolation of 36 strains. A hbb gene quantitative real-time polymerase chain reaction (PCR) based on melting temperature determination and ospA gene sequencing were used to genotype the isolated spirochetes. The species identified based on the hbb gene real-time PCR were: Borrelia lusitaniae (44.4%), Borrelia afzelii (36.1%), Borrelia garinii (13.9%) and Borrelia valaisiana (5.6%), whereas the ospA sequence analysis revealed the occurrence of Borrelia bavariensis. This is the first report of the isolation of B. lusitaniae, B. garinii, B. bavariensis and B. valaisiana strains in Serbia.

Keywords: Borrelia burgdorferi s.l.; Ixodes ricinus; characterization; cultivation; pathogen; quantitative PCR; vector.