Rodents as potential reservoirs for Borrelia spp. in northern Chile / Roedores como potenciais reservatórios de Borrelia spp. no norte do Chile

Abstract Small mammals play an essential role in the transmission and maintenance cycles of Borrelia spirochetes. In Chile, recent studies have characterized novel Borrelia genotypes in ticks collected from small mammals, a fact that suggests these vertebrates are hosts for spirochetes from this genus. Considering this evidence, the goal of this study was to determine the presence of Borrelia DNA in small mammals inhabiting northern Chile. In winter of 2018, 58 small mammals were captured in five localities. Blood samples were collected from rodents and DNA was extracted to determine the presence of Borrelia DNA by PCR targeting the flaB gene and rrs-rrlA intergenic spacer (IGS). From three individuals (5%), belonging to two rodent species of Cricetidae family (Phyllotis xanthopygus and Oligoryzomys longicaudatus), we retrieved three flaB and two IGS Borrelia genotypes. Phylogenetic analyses performed with both Maximum Likelihood and Bayesian inferences showed that our sequences grouped with homologous genotypes from the relapsing fever and Lyme borreliosis groups. Our findings suggest that P. xanthopygus and O. longicaudatus rodents may play a role as reservoirs for borrelial spirochetes in Chile.

Resumo Pequenos mamíferos possuem um papel essencial na transmissão e manutenção de espiroquetas do gênero Borrelia. No Chile, estudos recentes têm descrito novos genótipos de Borrelia em carrapatos, parasitando pequenos mamíferos. Isso sugere que esses vertebrados podem atuar como possíveis reservatórios dessas espiroquetas. Considerando-se essa evidência, o objetivo deste estudo foi determinar a presença de DNA de Borrelia em pequenos mamíferos da região norte do Chile. Durante o inverno de 2018, 58 pequenos mamíferos foram capturados em cinco localidades. Amostras de sangue obtidas a partir dos indivíduos capturados foram submetidas à extração de DNA e ensaios de PCR, para a detecção de Borrelia spp. baseados no gene flaB e espaçador intergênico rrs-rrlA (IGS). A partir de três espécimes (5%) pertencentes a duas espécies de roedores da família Cricetidae (Phyllotis xanthopygus e Oligoryzomys longicaudatus) obtiveram-se três genótipos de Borrelia para o gene flaB e dois para IGS. Análises filogenéticas inferidas, usando-se os métodos Bayesiano e de Máxima Verossimilhança, indicaram que as sequências geradas neste estudo agrupam-se com borrelias do grupo da Febre Recorrente e Borreliose de Lyme. Os achados deste estudo sugerem que roedores P. xanthopygus e O. longicaudatus poderiam atuar como possíveis reservatórios para Borrelia spp. no Chile.

Molecular epidemiology of Lyme disease spirochetes based on a probe complementary to ribosomal RNA

Lyme disease is caused by the spirochete, Borrelia burgdorferi, a bacteria which infects many vertebrates including humans. Borrelia have been isolated from many parts of the world, and there is interest to identify commun genetic markers to improve molecular methods of diagnosis, and to aid in understanding varied manifestations of the disease. A total of 48 Borrelia burgdorferi strains, including: 38 isolated from ticks (Ixodes dammini, I. persulcatus, I. ricinus and I. pacificus), 3 from animals (dog, bird and hamster), and 7 from human clinical cases (skin, CSF, plasma and blood) from different geographic areas, were studied by DNA/DNA hybridization and rRNA gene restriction patterns by using a biotinylated pKK3535 probe (Altewegg M., Mayer L.W., 1989). The migration patterns of rRNA generestriction fragments after clevage by Hind III separate these strains into 5 ribotypes of Borrelia burgdorferi: Type I (38 American, 2 European strains); Type II (13 American strains); Type III (3 Asian and 1 European strains); Type IV (1 European and 2 Asian strains) and Type V (1 Asian strain). The use of ribotyping has provided and additional tool to investigate the diferences or commun patterns which cause various Lyme disease syndromes.