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Experimental animal models and vectors of Leishmania (Mundinia)
Bečvář, Tomáš ; Sádlová, Jovana (advisor) ; Courtenay, Orin (referee) ; Soares Maia, Carla Alexandra (referee)
Leishmania are vector-borne dixenous protozoan parasites of vertebrates causing diseases collectively called leishmaniases, which threaten more than 1 billion people mainly in tropical and subtropical regions. These parasites are divided into four subgenera: Leishmania, Viannia, Sauroleishmania, and Mundinia. The last named are geographically widely dispersed and their distribution covers all continents except Antarctica. Although their medical and veterinary importance is increasing, there is currently almost no information on natural reservoir hosts, vector species, and experimental research options due to the very limited range of model animals. This thesis summarizes our efforts to unravel possible vectors and laboratory models for this subgenus. In the first three studies, we focused on potential models; therefore, we experimentally infected guinea pigs (Cavia porcellus), BALB/c mice, Chinese hamsters (Cricetulus griseus), and steppe lemmings (Lagurus lagurus) with five species of Mundinia and we also tested reservoir potential of African grass rat (Arvicanthis niloticus) and Natal multimammate mouse (Mastomys natalensis) to Leishmania chancei. The second part focused on potential vectors of the parasites. We experimentally infected biting midges Culicoides sonorensis and sand flies sharing...
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Development of flagellates of the genus Porcisia and subgenus Mundinia in phlebotomine sand flies (Diptera: Psychodidae) and ceratopogonid midges (Diptera: Ceratopogonidae)
Bačíková, Dominika ; Sádlová, Jovana (advisor) ; Modrý, David (referee)
The main part of the thesis is focused on flagellates of the genus Porcisia, parasitizing Neotropical porcupines with unknown vectors. The development of two known species of this genus (P. deanei and P. hertigi) in two sand fly species (Lu. migonei, Lu. longipalpis) and biting midges C. sonorensis was studied using experimental infections. While P. hertigi did not survive defecation in females of either vector, P. deanei formed strong mature infections in 51-61% of Lu. longipalpis and in a smaller percentage in Lu. migonei (7 %) and C. sonorensis (7 %). Porcisia showed significantly smaller size than the control species L. infantum but formed the same morphological forms. The localization of P. deanei was exceptional; infections were detected predominantly in Malpighian tubules. Further experiments demonstrated the presence of P. deanei in the urine of Lu. longipalpis excreted during prediuresis and successful transmission of parasites to BALB/c mice by this unique route. Thus, Lu. longipalpis is a competent vector of P. deanei, but other vector species may be involved in transmission at endemic localities. A minor part is focused on the comparison of the morphology of two Mundinia species - L. martiniquensis and L. orientalis - during development in biting midges C. sonorensis and sand flies Ph....
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Leishmaniases and their vectors in western Africa
Hošková, Anna ; Dvořák, Vít (advisor) ; Sádlová, Jovana (referee)
Leishmaniasis is a parasitic disease transmitted by sand flies. In West Africa, leishmaniasis is endemic and we distinguish cutaneous, visceral and mucocutaneous form of the disease. The most common form in this area is cutaneous leishmaniasis, which is caused by Leishmania major, Leishmania tropica and a new, as yet undescribed species Leishmania sp. from Ghana. The causative agents of visceral leishmaniasis are Leishmania donovani and Leishmania infantum. Phlebotomus duboscqi is a confirmed vector of L. major in this region. Vectors of Leishmania sp. from Ghana and vectors of visceral leishmaniasis remain unknown in West Africa. Sand flies of the genus Sergentomyia or Culicoides biting midges are considered as potential alternative vectors in this area. The confirmed reservoir hosts of L. major in some countries are the rodents Tatera gambiana, Arvicanthis niloticus and Mastomys erythroleucus, but in most states they are not confirmed. The reservoir hosts of visceral leishmaniasis are mainly dogs. Some West African states used to be French colonies, and there are many people of African descent in France who come to visit their relatives in West Africa. This poses a risk of import of leishmaniasis to non-endemic areas. The aim of this bachelor thesis is to summarize the current knowledge about the...
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Genus Sergentomyia and its role in the transmission of Leishmania
Hlavačková, Kristýna ; Dvořák, Vít (advisor) ; Sádlová, Jovana (referee)
Sand flies, members of the subfamily Phlebotominae do not occur in the CzechRepublic, but as near as in the Mediterraneantheir fauna is quite abundant. Sand flies can be found approximately between 50řN and 40řS. Species of genus Phlebotomus, Sergentomyia and Lutzomyia include medically and veterinary important vectors of viral and bacterial diseases as well as leishmaniasis, one of the most important human protozoal diseases. 321 years have passed since the first sand fly was described, but only 110 years ago intensive taxonomic work began. Over the years many classification systems have been proposed, mainly based on division of morphological characters. The classification is not clearly settled even after several taxonomic revisions and many questions remain, especially about genus Sergentomyia, which is repeatedly mentioned in connection with transmission of mammals' leishmaniasis. This bachelor thesis gives contemporary summary of taxonomic knowledge of sand flies; special attention is given to genus Sergentomyia.
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Types of Leishmania development in phlebotomine species
Nováková, Julie ; Votýpka, Jan (advisor) ; Sádlová, Jovana (referee)
The aim of this thesis is to depict the means of Leishmania development in sand flies (Phlebotominae). Three main Leishmania evolutionary branches (subgenera Leishmania, Viannia and Sauroleishmania) have a slightly different development in the vector, the Sauroleishmania development being the least known. The vector-bound development of the subgenus Leishmania is localized in the midgut and foregut of the sand fly solely, whereas species of the Viannia subgenus occur in the hindgut (although the necessity of this phase for a successful development and infection of the vertebrate host is a matter of doubt) and the subgenus Sauroleishmania development is according to literature confined to the hindgut. Quite little is known about the genus Endotrypanum, according to phylogenetic data set inside the Leishmania group. In my bachelor thesis, I review up-to-date literature on the topic of different types of Leishmania development inside the sand flies and their probable reasons.
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Comparison of different rodent species as hosts of human pathogenic leishmania.
Vojtková, Barbora ; Sádlová, Jovana (advisor) ; Kodym, Petr (referee) ; Shaw, Jeffrey Jon (referee)
6 ABSTRACT Leishmania parasites (Kinetoplastida: Trypanosomatidae) are causative agents of leishmaniases, a group of vector-borne diseases with various manifestations and complex epidemiology. Principal vectors are sand flies (Diptera: Psychodidae) and among mammalian hosts, rodents are predominantly represented. Rodents are also the most common laboratory models for the research of leishmaniases. However, reservoirs of most Leishmania species are still poorly recognized and the scope of standard model hosts is still insufficient to mimic well the wide spectrum of leishmaniases. This PhD thesis summarizes three different topics, all dealing with experimental infections of rodents with important human parasites - Leishmania major and L. donovani. The first topic was focused on the effect of sand fly saliva on the development of cutaneous leishmaniasis. BALB/c mice infected intradermally with L. major were repeatedly bitten by P. duboscqi females every two weeks. The multiple and repeated sand fly bites significantly enhanced the development of cutaneous lesions and increased parasite load. The second topic was aimed at enrichment of the spectrum of laboratory model animals for Leishmania research. Three Asian rodent species (Cricetulus griseus, Lagurus lagurus and Phodopus sungorus) were infected with L....
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Autogeny by phlebotomine sandflies
Pavlasová, Michaela ; Votýpka, Jan (advisor) ; Sádlová, Jovana (referee)
1 Abstract In haematophagous insect autogeny means an eggs development and ability to set first egg batch without previous blood-feeding on a host. Autogeny developed in several groups of invertebrates mainly order Diptera and more rarely orders Heteroptera and Acari. It occurs mostly as an alternative possibility of development in case of unsuitable conditions or absence of hosts. This thesis includes present findings about autogeny among subfamily Phlebotominae and families Culicidae, Simuliidae, Ceratopogonidae and Tabanidae. The thesis focuses on factors influencing autogeny such as nutrition during larval development, geographic and genetic factors, temperature and photoperiodic aspects. The thesis is targeted mostly on sandflies, important vectors of many pathogens, and on influence of autogeny on its vectorial potential. Key words: autogeny, ovarian development, Phlebotomus, Culicidae, Simuliidae, Ceratopogonidae, Tabanidae
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Leishmania tropica: immunopathology and genetic control
Sohrabi, Yahya ; Lipoldová, Marie (advisor) ; Pravenec, Michal (referee) ; Sádlová, Jovana (referee)
Leishmaniasis is a neglected tropical disease caused by protozoan parasites of the genus Leishmania and transmitted by female sand flies. The outcome of Leishmania infection depends both on host and pathogen factors. Similarly as L. major, L. tropica very often causes cutaneous leishmaniasis in humans, but in rare occasions can also visceralize and cause systemic disease. Leishmaniasis cause by L. tropica has become a major public health problem in different endemic foci due to recent outbreaks in several urban areas and spread to new regions. The complications of the disease and lack of safe and effective drug and vaccine against the L. tropica infection require considerable attention to studies of the host-L. tropica interaction. Until recently, the research of leishmaniasis caused by L. tropica was limited due to lack of suitable inbred model and difficulties in inducing infection in animals. The aims of the present project were development of a suitable mouse model of the infection caused by L. tropica, and the study of mechanisms of the disease, and also mapping controlling genes/loci. We analysed susceptibility to L. tropica infection using recombinant congenic (RC) CcS/Dem mouse strains. These strains differ greatly in susceptibility to L. major due to random distribution of 12.5% of STS...
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Role of asymptomatic hosts in leishmaniasis transmission.
Sandner, Bruno ; Sádlová, Jovana (advisor) ; Kodym, Petr (referee)
Leishmania parasites have a digenetic-life cycle, circulating between vertebrate hosts and insect vectors, mainly phlebotomine sand flies (Diptera: Phlebotominae). Mammals serve as principal reservoirs of the disease and maintain the leishmania population even in the absence of the vector. Knowledge of the role of asymptomatic hosts in parasite transmission is one of the key prerequisites to understand epidemiology of leishmaniases. The aim of this work is to summarize the studies on asymptomatic hosts of visceral leishmaniasis caused by L. infantum and L. donovani. In L. infantum, asymptomatic hosts have been shown to be involved in transmission, namely dogs, humans, and other putative reservoir hosts. Asymptomatic dogs infect the same proportion of vectors as symptomatic dogs, and in humans, HIV coinfection significantly increased the infectiousness. VL caused by L. donovani is regarded as mostly anthroponotic, but the parasite has been often detected in animal hosts and zoonotic transmission has been suggested in East Africa. Transmission from asymptomatic individuals has not been established, but the studies on this topic are very scarce. Further intensive research is needed to confirm the role of potential reservoir hosts and asymptomatic individuals in the transmission of leishmaniases....
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Vývoj leishmanií v přenašečích rodu Phlebotomus
Sádlová, Jovana
DISSERTATION ABSTRACT Development of Leishmania parasites in vector sandflies (Diptera: Phlebotominae) Jovana Sádlová Introduction. The work is dealing with two topics: (1) factors affecting development of Leishmania parasites in sandfly vectors and (2) mechanism of Leishmania transmission to the vertebrate host. It includes a review on Leishmania - sandfly - host interactions, four papers published in scientific journals and one manuscript submitted for publication. (1) Within the sandfly gut, Leishmania promastigotes encounter a number of factors which affect their development. They are usually well-adapted to the habitat inside the gut of their natural vectors, but characters of the parasites crucial for the development in the vector have not been elucidated. The main cell-surface molecules of promastigotes, lipophosphoglycan (LPG) and metalloprotease gp63, are known as the most important virulence factors influencing Leishmania interactions with the vertebrate host. However, their role in the vector part of Leishmania life-cycle remains to be clarified. The idea of the work is based on the fact that there are differences in the courses of sandfly infections with various strains and lines of L. major. Therefore, a detailed characterization of individual strains/lines may lead to the recognition of a...
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