Absence of transovarial transmission of Borrelia duttonii, a tick-borne relapsing fever agent, by the vector tick Ornithodoros moubata.

We examined the vector competence of the tick, Ornithodoros moubata, using laboratory-reared gerbils as hosts. Transmission of the relapsing fever agent Borrelia duttonii occurred efficiently from infected ticks to uninfected gerbils and from infected gerbils to uninfected ticks. Spirochetes were maintained stably in the ticks for at least 3 months, but they disappeared from the bloodstream of infected gerbils after three episodes of spirochetemia.

Molecular mechanisms for the variation of mitochondrial gene content and gene arrangement among chigger mites of the genus Leptotrombidium (Acari: Acariformes).

The gene content of a mitochondrial (mt) genome, i.e., 37 genes and a large noncoding region (LNR), is usually conserved in Metazoa.

Novel mitochondrial gene content and gene arrangement indicate illegitimate inter-mtDNA recombination in the chigger mite, Leptotrombidium pallidum.

To better understand the evolution of mitochondrial (mt) genomes in the Acari (mites and ticks), we sequenced the mt genome of the chigger mite, Leptotrombidium pallidum (Arthropoda: Acari: Acariformes). This genome is highly rearranged relative to that of the hypothetical ancestor of the arthropods and the other species of Acari studied. The mt genome of L.

Evolution of duplicate control regions in the mitochondrial genomes of metazoa: a case study with Australasian Ixodes ticks.

To investigate the evolution pattern and phylogenetic utility of duplicate control regions (CRs) in mitochondrial (mt) genomes, we sequenced the entire mt genomes of three Ixodes species and part of the mt genomes of another 11 species. All the species from the Australasian lineage have duplicate CRs, whereas the other species have one CR. Sequence analyses indicate that the two CRs of the Australasian Ixodes ticks have evolved in concert in each species.

New World relapsing fever Borrelia found in Ornithodoros porcinus ticks in central Tanzania.

Ticks were collected from 8 houses in Mvumi Mission village, near Dodoma, Tanzania. All ticks were examined for Borrelia infestation by flagellin gene-based nested polymerase chain reaction. All houses were highly infested with ticks, and all ticks collected were of the Ornithodoros porcinus species.

A newly identified tick-borne Borrelia species and relapsing fever in Tanzania.

Tick-borne relapsing fever caused by the spirochaete Borrelia duttonii is a common cause of serious illness in central Tanzania. Screening of Ornithodoros sp ticks from infested houses for the presence of B duttonii had detected a previously unidentified species of Borrelia. We investigated whether this species infected the human population in a central Tanzanian village, by use of blood slide examination and PCR.

The 44-kb linear plasmid molecule in the relapsing fever agent Borrelia duttonii strain Ly serve as a preservation of vmp genes.

Borrelia duttonii strain Ly, a causative agent of relapsing fever, contains a linear one megabase chromosome and 12 linear plasmid molecules. Here we report that the sequence of the 44-kb linear plasmid of strain Ly is found to contain variable major protein (vmp) genes for antigenic variation of relapsing fever borreliae. The determined sequence is of 44,010 bp except for both ends of the molecule.