The abundance of pathogenic African trypanosomes in the salivary secretions of wild<i>Glossina pallidipes</i>

Otieno, L. H.; Darji, N

doi:10.1080/00034983.1979.11687300

Cited by 27 publications

(12 citation statements)

References 7 publications

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“…They swim freely in the saliva and represent the infective form that is pre-adapted to survive in the mammalian host (Otieno and Darji, 1979) (Figure 5H,I). The cell body appears elastic and is deformed in the shape of the flagellar waveform.…”

Section: Resultsmentioning

confidence: 99%

Developmental adaptations of trypanosome motility to the tsetse fly host environments unravel a multifaceted in vivo microswimmer system

Schuster

Krüger

Subota

et al. 2017

eLife

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The highly motile and versatile protozoan pathogen Trypanosoma brucei undergoes a complex life cycle in the tsetse fly. Here we introduce the host insect as an expedient model environment for microswimmer research, as it allows examination of microbial motion within a diversified, secluded and yet microscopically tractable space. During their week-long journey through the different microenvironments of the fly´s interior organs, the incessantly swimming trypanosomes cross various barriers and confined surroundings, with concurrently occurring major changes of parasite cell architecture. Multicolour light sheet fluorescence microscopy provided information about tsetse tissue topology with unprecedented resolution and allowed the first 3D analysis of the infection process. High-speed fluorescence microscopy illuminated the versatile behaviour of trypanosome developmental stages, ranging from solitary motion and near-wall swimming to collective motility in synchronised swarms and in confinement. We correlate the microenvironments and trypanosome morphologies to high-speed motility data, which paves the way for cross-disciplinary microswimmer research in a naturally evolved environment.DOI: http://dx.doi.org/10.7554/eLife.27656.001

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Section: Resultsmentioning

confidence: 99%

Developmental adaptations of trypanosome motility to the tsetse fly host environments unravel a multifaceted in vivo microswimmer system

Schuster

Krüger

Subota

et al. 2017

eLife

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“…Here, it is clear that multiple transmission of the parasite in a single tsetse feeding cycle increases its survival and circulation within the natural mammalian host population. In the case of the human pathogenic T. brucei sp., where the numbers of salivary gland infected tsetse flies in the natural population are extremely low [<0.1%, [40]–[42]], the increased biting rate of the infected tsetse could be a major epidemiological factor.…”

Section: Discussionmentioning

confidence: 99%

Trypanosoma brucei Modifies the Tsetse Salivary Composition, Altering the Fly Feeding Behavior That Favors Parasite Transmission

et al. 2010

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Tsetse flies are the notorious transmitters of African trypanosomiasis, a disease caused by the Trypanosoma parasite that affects humans and livestock on the African continent. Metacyclic infection rates in natural tsetse populations with Trypanosoma brucei, including the two human-pathogenic subspecies, are very low, even in epidemic situations. Therefore, the infected fly/host contact frequency is a key determinant of the transmission dynamics. As an obligate blood feeder, tsetse flies rely on their complex salivary potion to inhibit host haemostatic reactions ensuring an efficient feeding. The results of this experimental study suggest that the parasite might promote its transmission through manipulation of the tsetse feeding behavior by modifying the saliva composition. Indeed, salivary gland Trypanosoma brucei-infected flies display a significantly prolonged feeding time, thereby enhancing the likelihood of infecting multiple hosts during the process of a single blood meal cycle. Comparison of the two major anti-haemostatic activities i.e. anti-platelet aggregation and anti-coagulation activity in these flies versus non-infected tsetse flies demonstrates a significant suppression of these activities as a result of the trypanosome-infection status. This effect was mainly related to the parasite-induced reduction in salivary gland gene transcription, resulting in a strong decrease in protein content and related biological activities. Additionally, the anti-thrombin activity and inhibition of thrombin-induced coagulation was even more severely hampered as a result of the trypanosome infection. Indeed, while naive tsetse saliva strongly inhibited human thrombin activity and thrombin-induced blood coagulation, saliva from T. brucei-infected flies showed a significantly enhanced thrombinase activity resulting in a far less potent anti-coagulation activity. These data clearly provide evidence for a trypanosome-mediated modification of the tsetse salivary composition that results in a drastically reduced anti-haemostatic potential and a hampered feeding performance which could lead to an increase of the vector/host contact and parasite transmission in field conditions.

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“…This is not direct and requires several migration, proliferation and differentiation steps that take place in a strictly defined chronological order in specific fly tissues (up to 3 weeks) (Oberle et al, 2010;Rotureau et al, 2011;Sharma et al, 2008;Van Den Abbeele et al, 1999;Vickerman, 1985). Once trypanosomes are present in the salivary glands, a fly can produce hundreds of metacyclic parasites per day (Otieno and Darji, 1979) and remains infective for its whole life (~3 months), a meaningful fact considering that a rather low proportion of flies is infected (< 0.1%) (Aksoy et al, 2003;Brun et al, 2009). Moreover, fly behavior is altered by trypanosome infection that modifies the salivary composition, resulting in a drastically reduced anti-hemostatic potential and a hampered feeding performance.…”

Section: Introductionmentioning

confidence: 99%

A new asymmetric division contributes to the continuous production of infective trypanosomes in the tsetse fly

et al. 2012

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SUMMARYAfrican trypanosomes are flagellated protozoan parasites that cause sleeping sickness and are transmitted by the bite of the tsetse fly. To complete their life cycle in the insect, trypanosomes reach the salivary glands and transform into the metacyclic infective form. The latter are expelled with the saliva at each blood meal during the whole life of the insect. Here, we reveal a means by which the continuous production of infective parasites could be ensured. Dividing trypanosomes present in the salivary glands of infected tsetse flies were monitored by live video-microscopy and by quantitative immunofluorescence analysis using molecular markers for the cytoskeleton and for surface antigens. This revealed the existence of two distinct modes of trypanosome proliferation occurring simultaneously in the salivary glands. The first cycle produces two equivalent cells that are not competent for infection and are attached to the epithelium. This mode of proliferation is predominant at the early steps of infection, ensuring a rapid colonization of the glands. The second mode is more frequent at later stages of infection and involves an asymmetric division. It produces a daughter cell that matures into the infective metacyclic form that is released in the saliva, as demonstrated by the expression of specific molecular markers -the calflagins. The levels of these calcium-binding proteins increase exclusively in the new flagellum during the asymmetric division, showing the commitment of the future daughter cell to differentiation. The coordination of these two alternative cell cycles contributes to the continuous production of infective parasites, turning the tsetse fly into an efficient and long-lasting vector for African trypanosomes.

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The abundance of pathogenic African trypanosomes in the salivary secretions of wildGlossina pallidipes

Cited by 27 publications

References 7 publications

Developmental adaptations of trypanosome motility to the tsetse fly host environments unravel a multifaceted in vivo microswimmer system

Developmental adaptations of trypanosome motility to the tsetse fly host environments unravel a multifaceted in vivo microswimmer system

Trypanosoma brucei Modifies the Tsetse Salivary Composition, Altering the Fly Feeding Behavior That Favors Parasite Transmission

A new asymmetric division contributes to the continuous production of infective trypanosomes in the tsetse fly

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