Genetic characterization of Rickettsia in mites (Dermanyssoidea)

Abstract

Currently, genus Rickettsia comprises 31 recognized species and numerous uncharacterized strains causing diseases in both humans and domestic and wild animals. The development of molecular tools over recent decades has resulted in reorganizations in the rickettsiae taxonomy. Rickettsia spp. are vectored mainly by hematophagous arthropods. Mesostigmatid mites, which feed on very different species of small rodents, may be reservoirs as well as vectors of some pathogenic rickettsiae. The aim of this study was to investigate the presence of Rickettsia spp. in mites parasitizing small rodents and to genetically characterize rickettsiae strains obtained from different mites species. A total of 550 parasitic mites of five species belonging to Laelapidae family were collected from small rodents in Lithuania during 2013 – 2014. Rickettsia DNA was detected in four mite species Laelaps agilis, Hyperlaelaps microti, Eulaelaps stabularis and Myonyssus gigas. PCR and sequence analysis of the partial 17kDa and gltA genes revealed the presence of three Rickettsia species Rickettsia helvetica, Rickettsia felis, and unidentified Rickettsia sp. Phylogenetic analysis of Rickettsia strains isolated from different mite species revealed genetic heterogeneity and provides evidence for host-specific strain variation. To our knowledge, this is the first evidence of the presence of R. felis in L. agilis and H. microti mites, and the first report of the occurrence and molecular characterization of Rickettsia spp. in Mesostigmata mites in the Baltic region.