Genome Sequence of Borrelia crocidurae Strain 03-02, a Clinical Isolate from Senegal

Rodents as Hosts of Pathogens and Related Zoonotic Disease Risk

Rodents are known to be reservoir hosts for at least 60 zoonotic diseases and are known to play an important role in their transmission and spread in different ways. We sampled different rodent communities within and around human settlements in Northern Senegal, an area subjected to major environmental transformations associated with global changes. Herein, we conducted an epidemiological study on their bacterial communities. One hundred and seventy-one (171) invasive and native rodents were captured, 50 from outdoor trapping sites and 121 rodents from indoor habitats, consisting of five species. The DNA of thirteen pathogens was successfully screened on the rodents' spleens. We found: 2.3% of spleens positive to Piroplasmida and amplified one which gave a potentially new species Candidatus "Theileria senegalensis"; 9.35% of Bartonella spp. and amplified 10, giving three genotypes; 3.5% of filariasis species; 18.12% of Anaplasmataceae species and amplified only 5, giving a new potential species Candidatus "Ehrlichia senegalensis"; 2.33% of Hepatozoon spp.; 3.5% of Kinetoplastidae spp.; and 15.2% of Borrelia spp. and amplified 8 belonging all to Borrelia crocidurae. Some of the species of pathogens carried by the rodents of our studied area may be unknown because most of those we have identified are new species. In one bacterial taxon, Anaplasma, a positive correlation between host body mass and infection was found. Overall, male and invasive rodents appeared less infected than female and native ones, respectively.

Genomic blueprint of a relapsing fever pathogen in 15th century Scandinavia

Louse-borne relapsing fever (LBRF) is known to have killed millions of people over the course of European history and remains a major cause of mortality in parts of the world. Its pathogen, Borrelia recurrentis, shares a common vector with global killers such as typhus and plague and is known for its involvement in devastating historical epidemics such as the Irish potato famine. Here, we describe a European and historical genome of Brecurrentis, recovered from a 15th century skeleton from Oslo. Our distinct European lineage has a discrete genomic makeup, displaying an ancestral oppA-1 gene and gene loss in antigenic variation sites. Our results illustrate the potential of ancient DNA research to elucidate dynamics of reductive evolution in a specialized human pathogen and to uncover aspects of human health usually invisible to the archaeological record.

Monoclonal Antibodies for the Diagnosis of Borrelia crocidurae

Relapsing fever borreliae, produced by ectoparasite-borne Borrelia species, cause mild to deadly bacteremia and miscarriage. In the perspective of developing inexpensive assays for the rapid detection of relapsing fever borreliae, we produced 12 monoclonal antibodies (MAbs) against Borrelia crocidurae and characterized the two exhibiting the highest titers. P3A10 MAb reacts with the 35.6-kDa flagellin B (flaB) of B. crocidurae while P6D9 MAb recognizes a 35.1-kDa variable-like protein (Vlp) in B. crocidurae and a 35.2-kDa Vlp in Borrelia duttonii. Indirect immunofluorescence assay incorporating relapsing fever and Lyme group borreliae and 11 blood-borne organisms responsible for fever in West Africa confirmed the reactivity of these two MAbs. Combining these two MAbs in indirect immunofluorescence assays detected relapsing fever borreliae including B. crocidurae in ticks and the blood of febrile Senegalese patients. Both antibodies could be incorporated into inexpensive and stable formats suited for the rapid point-of-care diagnosis of relapsing fever. These first-ever MAbs directed against African relapsing fever borreliae are available for the scientific community to promote research in this neglected field.

Laboratory Diagnosis of Tick-Borne African Relapsing Fevers: Latest Developments

In Africa, relapsing fevers caused by ectoparasite-borne Borrelia species are transmitted by ticks, with the exception of Borrelia recurrentis, which is a louse-borne spirochete. These tropical diseases are responsible for mild to deadly spirochetemia. Cultured Borrelia crocidurae, Borrelia duttonii, and Borrelia hispanica circulate alongside at least six species that have not yet been cultured in vectors. Direct diagnosis is hindered by the use of non-specific laboratory tools. Indeed, microscopic observation of Borrelia spirochaeta in smears of peripheral blood taken from febrile patients lacks sensitivity and specificity. Although best visualized using dark-field microscopy, the organisms can also be detected using Wright–Giemsa or acridine orange stains. PCR-based detection of specific sequences in total DNA extracted from a specimen can be used to discriminate different relapsing fever Borreliae. In our laboratory, we developed a multiplex real-time PCR assay for the specific detection of B. duttonii/recurrentis and B. crocidurae: multispacer sequence typing accurately identified cultured relapsing fever borreliae and revealed diversity among them. Other molecular typing techniques, such as multilocus sequence analysis of tick-borne relapsing fever borreliae, showed the potential risk of human infection in Africa. Recent efforts to culture and sequence relapsing fever borreliae have provided new information for reassessment of the diversity of these bacteria. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been reported as a means of identifying cultured borreliae and of identifying both vectors and vectorized pathogens such as detecting relapsing fever borreliae directly in ticks. The lack of a rapid diagnosis test restricts the management of such diseases. We produced monoclonal antibodies against B. crocidurae in order to develop cheap assays for the rapid detection of relapsing fever borreliae. In this paper, we review point-of-care diagnosis and confirmatory methods.