Tsetse Fly Host Research Articles

Host preference of tsetse: an important tool to appraise the Nagana risk of cattle in the cotton zone of Mali

Nagana, a vector-borne epizootic caused by trypanosomes, severely constrains the use of draught animals in the cotton zone of south-eastern Mali. The disease causes considerable economic losses for the local farmers due to high mortality and morbidity ensuing productivity losses. Nagana is routinely controlled by the use of trypanocides and an overreliance on their use throughout past decades resulted in multiple drug resistance of trypanosomes in most parts of West Africa's cotton belt. Designing alternative, effective vector control strategies requires an identification of the preferred hosts of tsetse flies through blood meal analysis as a prerequisite for estimating infection risk. A survey was, therefore, conducted between November 2008 and April 2009, catching 474 Glossina species which were dissected. Blood meals were smeared on filter paper (Whatman(®)-FTA-Cards) for laboratory analysis. DNA extractions and amplification using universal vertebrate cytochrome b primers of 120 assorted samples detected 74 DNA-containing specimens. The subsequent use of cattle-specific primers yielded 52 visible amplicons in the gel electrophoresis. Sequencing and BLASTN(®) analysis of the remaining samples revealed 19 blood meals matching with existing sequences of the human genome in Genbank(®). Two samples originated from crocodiles whereas one was unidentifiable.

The Trypanosoma brucei Life Cycle Switch TbPTP1 Is Structurally Conserved and Dephosphorylates the Nucleolar Protein NOPP44/46

Trypanosoma brucei adapts to changing environments as it cycles through arrested and proliferating stages in the human and tsetse fly hosts. Changes in protein tyrosine phosphorylation of several proteins, including NOPP44/46, accompany T. brucei development. Moreover, inactivation of T. brucei protein-tyrosine phosphatase 1 (TbPTP1) triggers differentiation of bloodstream stumpy forms into tsetse procyclic forms through unknown downstream effects. Here, we link these events by showing that NOPP44/46 is a major substrate of TbPTP1. TbPTP1 substrate-trapping mutants selectively enrich NOPP44/46 from procyclic stage cell lysates, and TbPTP1 efficiently and selectively dephosphorylates NOPP44/46 in vitro. To provide insights into the mechanism of NOPP44/46 recognition, we determined the crystal structure of TbPTP1. The TbPTP1 structure, the first of a kinetoplastid protein-tyrosine phosphatase (PTP), emphasizes the conservation of the PTP fold, extending to one of the most diverged eukaryotes. The structure reveals surfaces that may mediate substrate specificity and affords a template for the design of selective inhibitors to interfere with T. brucei transmission.

Tsetse fly blood meal modification and trypanosome identification in two sleeping sickness foci in the forest of southern Cameroon

The blood meal origins of 222 tsetse flies (213 Glossina palpalis palpalis, 7 Glossina pallicera pallicera, one Glossina nigrofusca and one Glossina caliginea) caught in 2008 in two Human African trypanosomiasis foci (Bipindi and Campo) of south Cameroon were investigated. 88.7% of tsetse flies blood meals were identified using the heteroduplex method and the origin of the remaining blood meals (11.3%) was identified by sequencing the cytochrome B gene. Most of the meals were from humans (45.9%) and pigs (37.4%), 16.7% from wild animals. Interestingly, new tsetse fly hosts including turtle ( Trionyx and Kinixys) and snake ( Python sebae) were identified. Significant differences were recorded between Bipindi where the blood meals from pigs were predominant (66.7% vs 23.5% from humans) and Campo where blood meals from humans were predominant (62.9% vs 22.7% from pigs). Comparison with the data recorded in 2004 in the same foci (and with the same molecular approach) demonstrated significant modifications of the feeding patterns: increase in blood meals from pigs in Bipindi (66.7% in 2008 vs 44.8% in 2004) and in Campo (20.5% in 2008 vs 6.8% in 2004), decrease in that from human (significant in Bipindi only). 12.6%, 8.1% and 2.7% of the flies were, respectively, Trypanosoma congolense forest type, Trypanosoma congolense savannah type and Trypanosoma brucei gambiense infected. These results demonstrate that tsetse fly feeding patterns can be specific of a given area and can evolve rapidly with time. They show an active circulation of a variety of trypanosomes in sleeping sickness foci of southern Cameroon.

Regulation of High-Affinity Iron Acquisition Homologues in the Tsetse Fly SymbiontSodalis glossinidius

Sodalis glossinidius is a facultative intracellular bacterium that is a secondary symbiont of the tsetse fly (Diptera: Glossinidae). Since studies with other facultative intracellular bacteria have shown that high-affinity iron acquisition genes are upregulated in vivo, we investigated the regulation of several Sodalis genes that encode putative iron acquisition systems. These genes, SG1538 (hemT) and SG1516 (sitA), are homologous to genes encoding periplasmic heme and iron/manganese transporters, respectively. hemT promoter- and sitA promoter-gfp fusions were constructed, and in both Escherichia coli and Sodalis backgrounds, expression levels of these fusions were higher when the bacteria were grown in iron-limiting media than when the bacteria were grown in iron-replete media. The Sodalis promoters were tested for iron regulation in an E. coli strain that lacks the fur gene, which encodes the iron-responsive transcriptional repressor Fur. Expression of the promoter-gfp fusions in the E. coli fur mutant was constitutively high in both iron-replete and iron-deplete media, and addition of either Shigella flexneri fur or Sodalis fur to a plasmid restored normal regulation. A Sodalis fur mutant was constructed by intron mutagenesis, and semiquantitative reverse transcription-PCR (RT-PCR) showed that iron repression of sitA expression was also abolished in this strain. In vivo expression analysis showed that hemT and sitA are expressed when Sodalis is within tsetse fly hosts, suggesting a biological role for these genes when Sodalis is within the tsetse fly.

Tsetse fly host preference from sleeping sickness foci in Cameroon: Epidemiological implications

To determine the tsetse fly host preferences in two sleeping sickness foci of southern Cameroon, four entomological surveys (two in each focus) were carried out. For the whole study, 4929 tsetse flies were caught: 3933 (79.8%) Glossina palpalis palpalis, 626 (12.7%) Glossina pallicera pallicera, 276 (5.6%) Glossina nigrofusca and 94 (1.9%) Glossina caliginea. One hundred and thirty-eight blood meals were collected and the origin of 118 (85.5%) meals was successfully identified: 38.4% from man, 23.9% from pig, 20.3% from sitatunga ( Tragelaphus spekeii), 2.2% from sheep and 0.7% from golden cat ( Profilis aurata). The number of Glossina palpalis palpalis with man blood meals is more important in the Human African Trypanosomiasis (HAT) focus showing endemic evolution (Campo) than in the focus (Bipindi) presenting a flare up of the disease. The consideration of both results of the prevalence of Trypanosoma brucei gambiense in vertebrate hosts and those of the tsetse fly host preferences indicates a wild animal reservoir of Gambian sleeping sickness and three transmission cycles (human, domestic and wild animals’ cycles) in southern Cameroon HAT foci.

Interspecific Transfer of Bacterial Endosymbionts between Tsetse Fly Species: Infection Establishment and Effect on Host Fitness

Tsetse flies (Glossina spp.) can harbor up to three distinct species of endosymbiotic bacteria that exhibit unique modes of transmission and evolutionary histories with their host. Two mutualist enterics, Wigglesworthia and Sodalis, are transmitted maternally to tsetse flies' intrauterine larvae. The third symbiont, from the genus Wolbachia, parasitizes developing oocytes. In this study, we determined that Sodalis isolates from several tsetse fly species are virtually identical based on a phylogenetic analysis of their ftsZ gene sequences. Furthermore, restriction fragment-length polymorphism analysis revealed little variation in the genomes of Sodalis isolates from tsetse fly species within different subgenera (Glossina fuscipes fuscipes and Glossina morsitans morsitans). We also examined the impact on host fitness of transinfecting G. fuscipes fuscipes and G. morsitans morsitans flies with reciprocal Sodalis strains. Tsetse flies cleared of their native Sodalis symbionts were successfully repopulated with the Sodalis species isolated from a different tsetse fly species. These transinfected flies effectively transmitted the novel symbionts to their offspring and experienced no detrimental fitness effects compared to their wild-type counterparts, as measured by longevity and fecundity. Quantitative PCR analysis revealed that transinfected flies maintained their Sodalis populations at densities comparable to those in flies harboring native symbionts. Our ability to transinfect tsetse flies is indicative of Sodalis ' recent evolutionary history with its tsetse fly host and demonstrates that this procedure may be used as a means of streamlining future paratransgenesis experiments.

Essential roles for GPI-anchored proteins in African trypanosomes revealed using mutants deficient in GPI8.

The survival of Trypanosoma brucei, the causative agent of Sleeping Sickness and Nagana, is facilitated by the expression of a dense surface coat of glycosylphosphatidylinositol (GPI)-anchored proteins in both its mammalian and tsetse fly hosts. We have characterized T. brucei GPI8, the gene encoding the catalytic subunit of the GPI:protein transamidase complex that adds preformed GPI anchors onto nascent polypeptides. Deletion of GPI8 (to give Deltagpi8) resulted in the absence of GPI-anchored proteins from the cell surface of procyclic form trypanosomes and accumulation of a pool of non-protein-linked GPI molecules, some of which are surface located. Procyclic Deltagpi8, while viable in culture, were unable to establish infections in the tsetse midgut, confirming that GPI-anchored proteins are essential for insect-parasite interactions. Applying specific inducible GPI8 RNAi with bloodstream form parasites resulted in accumulation of unanchored variant surface glycoprotein and cell death with a defined multinuclear, multikinetoplast, and multiflagellar phenotype indicative of a block in cytokinesis. These data show that GPI-anchored proteins are essential for the viability of bloodstream form trypanosomes even in the absence of immune challenge and imply that GPI8 is important for proper cell cycle progression.

Odor composition of preferred (buffalo and ox) and nonpreferred (waterbuck) hosts of some Savanna tsetse flies.

A previous study on the feeding responses of tsetse flies, Glossina morsitans morsitans, implicated the existence of allomonal barriers, both volatile and nonvolatile, on the nonpreferred host, waterbuck, Kobus defassa. In the present study, electroantennogram-active compounds in odors from waterbuck were compared with those of two preferred hosts of tsetse flies, buffalo, Syncerus caffer, and ox, Bos indicus. Odors from the three bovids were trapped on activated charcoal and/or reverse-phase (octadecyl bonded) silica and analyzed with a gas chromatography-linked electroantennographic detector (GC-EAD) and, where possible, identified by using gas chromatography-linked mass spectrometry (GC-MS) and chromatographic comparisons with authentic samples. The GC-EAD profiles (with G. m. morsitans antennae) of the odors of the two preferred hosts were comparable, comprising medium-chain, saturated or unsaturated aldehydes and phenols, with buffalo emitting a few more EAG-active aldehydes. Waterbuck odor gave a richer profile, consisting of fewer aldehydes but more phenolic components and a series of 2-ketones (C-C13) and delta-octalactone. This bovid also emits moderate amounts of C5-C9 straight-chain fatty acids, some of which were detected in buffalo and ox only in trace amounts. However, these did not elicit significant GC-EAD responses. Waterbuck profiles from the antennae of G. pallidipes showed broad similarity to those from G. m. morsitans, although the composition of aldehydes and ketones was somewhat different, indicating species-specific difference in the detection of host odors. Certain waterbuck-specific EAG-active components, particularly the 2-ketones and lactone, constitute a candidate allomonal blend in waterbuck odor.

A method for determining the reptilian hosts of tsetse flies

Journal Article A method for determining the reptilian hosts of tsetse flies Get access P.F.L. Boreham, P.F.L. Boreham Search for other works by this author on: Oxford Academic PubMed Google Scholar G.S. Gill G.S. Gill Search for other works by this author on: Oxford Academic PubMed Google Scholar Transactions of The Royal Society of Tropical Medicine and Hygiene, Volume 66, Issue 2, 1972, Pages 324–325, https://doi.org/10.1016/0035-9203(72)90198-8 Published: 01 January 1972

The natural hosts of tsetse files in Northern Nigeria.

The natural hosts of tsetse files in Northern Nigeria.

The natural hosts of tsetse flies in the forest belt of Nigeria and the Southern Cameroons.

The natural hosts of tsetse flies in the forest belt of Nigeria and the Southern Cameroons.