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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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Macrophages and nitric oxide in leishmania - sandfly - host interactions
Kratochvílová, Tereza ; Kolářová, Iva (advisor) ; Fialová, Anna (referee)
Leishmania reside fagolysosome of macrophages immediately after their entry to host where they multiply and consequently infect other macrophages or eventually other cells. A synthesis of a reactive reactant of oxygen and nitrogen is one of the mechanisms that some mammal cells are equipped with and that also contributes to eradication of leishmania. Nitric oxide rising during a metabolic change of L-arginine under the catalysis of NO synthase is of a large importance. Beyond cytotoxic function, nitric oxide is involved in signalling pathways for a neurotransmission (nNOS) and vasorelaxation (eNOS). Not all types of macrophages have ability to produce NO (iNOS). It is a heterogeneous group differing in immunological function and also in physiology. A group of classical activated macrophages represents an effective APC capable of efficient killing of intracellular pathogens. In addition to NO, they also secrete an inflammatory cytokines, which evolve an immune reaction towards to Th1. Contrary to this, a group of alternative activated macrophages is not capable of any efficient antigen presentation and nitric oxide production but produces L-ornithine, which is a precursor of polyamines, which leishmania utilizes for its own intracellular growth. For the mouse model, status of resistance and/or...
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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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Development of Leishmania from L.donovani complex in various vectors
Hrobáriková, Veronika
This thesis focuses on the development of protozoan parasites from Leishmania donovani complex in their insect vectors and summarizes results of five parts of the project I participated in during my Ph.D. studies. Sand flies of genera Phlebotomus and Lutzomyia are the only proven vectors of leishmaniasis, however, the role of alternative vectors, like ticks, fleas and biting midges is frequently discussed in the literature. In this work, we showed that Eurasian species of biting midge Culicoides nubeculosus does not support late stage infections of L. major and L. infantum. We also demonstrated that microscopical observation of Leishmania promastigotes in the digestive tract of bloodfeeding arthropods remains a crucial method for any conclusion about the vector competence of the suspected insect. In the second part of our study were compared the life-cycle parameters and vector competence of two Ethiopian P. orientalis colonies for L. donovani. Marked differences between colonies were found in life-cycle parametes, however, molecular analyses did not reveal any genetic differences. Experimental infections showed that both P. orientalis colonies are very susceptible to L. donovani infection and even the lowest infective dose tested (2 × 103 promastigotes/ml; corresponding to 1-2 promastigotes) was...
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Salivary proteins of sand flies and the immune aspects of Leishmania transmission
Kindlová, Michaela
Sand flies serve as the vectors of leishmaniasis and their saliva was shown to affect the outcome of Leishmania infection by immunomodulation of the host. On the other hand, sand fly saliva contains a large scale of farmacologically active proteins that are strongly immunogenous for bitten hosts and specific anti-saliva immunity initiated by repeated sand fly feeding provides protection against Leishmania infection. Specific cell-mediated immunity was shown to be the core of the protectivity; however, our data suggests that the protective immunity has certain limitations. In mice bitten by sand flies for prolonged periods, we observed the desenzitization in term of abrogation of the protective immunity. Thus, we can speculate that the protective effect of immunity is linked solely with the short-term exposure. Nevertheless, our experiments showed that this aspect is also conditioned by the immediate infection after the protective short-term immunization. Taken together, it seems that these limitations may explain the circulation of leishmaniasis in endemic areas, even though humans and animals are frequently immunized by bites of uninfected sand flies. Repeated sand fly feeding on various hosts also promotes production of anti-saliva antibodies that reflect the intensity of exposure. We...
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Molecular taxonomy of sand flies (Diptera: Psychodidae) in Europe
Grešová, Markéta ; Dvořák, Vít (advisor) ; Brzoňová, Jana (referee)
Phlebotomine sand flies (Diptera, Psychodidae) are small blood sucking insects which are only proven vectors of neglected tropical disease called leishmaniasis. Sand flies of the genus Phlebotomus act as vectors in the Old World and those of genus Lutzomyia are vectors in the New World. However, not all of them are capable of transmitting the disease. It is therefore crutial to conclusively determinate the species and have up-to-date knowledge of their natural occurence. Routine identification based on morphological characters is challenging due to intraspecific variability of these or their possible damage during the capture and preparation. In adition, correct assessment of distinctive cahracters, especially for females, is difficult and requires certain expertise. Thus, approaches of molecular taxonomy have been recently increasingly used for sand flies species determination. This thesis presents usage of DNA sequencing and MALDI-TOF protein profiling for routine determination of sand flies caught in southeastern Europe and adjacent regions, where we have lack of information of present sand flies species. Another part of this thesis focus on closer examination of relations between selected closely related species within species complexes. Key words: Phlebotomus, molacular identification, DNA...
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Leishmaniases of northern Africa and their vectors
Hanušniaková, Ida ; Dvořák, Vít (advisor) ; Sádlová, Jovana (referee)
Leishmaniasis belongs to the most important world human as well as animal diseases. It occurs in almost all continents. Its nearest area of occurrence from our point of view is the Mediterranean, including the states of North Africa. A significant portion of all registered cases occurs here and the prevalence has been increasing in last decades. Algeria is the second in the world in number of cases of cutaneous leishmaniasis and in the other countries the situation is quite similar. Two major forms of the disease occur in the region: visceral and cutaneous leishmaniasis. Leishmania major is the most abundant species in the are, followed by L. infantum and L. tropica. In the Old World, leishmanises are transmitted by sand flies of the genus Phlebotomus. The most important proven vectors are Phlebotomus papatasi, P. sergenti, P. perfiliewi or P. perniciosus. Rodents are considered to be main reservoir organisms (Psammomys obesus, Meriones shawi), together with dogs in which canine leishmaniasis may occur with clinical symptoms; at the same time they serve as reservoirs of the disease. This bachelor thesis summarizes occurrence of individual Leishmania species, clinical symptoms they cause in the hosts and their vectors in North Africa. Key words: leishmaniasis, phlebotomus, North Africa, Leishmania,...
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A comparison of the peritrophic matrix in four sand fly species (Diptera: Psychodidae) and its role in the Leishmania development (Kinetoplastida: Trypanosomatidae).
Homola, Miroslav ; Sádlová, Jovana (advisor) ; Hypša, Václav (referee)
anglický Phlebotomine sand flies (Diptera: Psychodidae) are the only proven vectors of Leishmania parasites (Kinetoplastida: Trypanosomatidae). In Nematoceran Diptera, including sand flies, adults produce a type 1 peritrophic matrix (PM) which is secreted in response to the distension of the midgut caused by blood meal. The PM is an acellular envelope composed of chitin fibres and proteins, which protects the midgut epithelium against abrasion and pathogens and improves digestion. In hematophagous insects, the PM also plays a central role in heme detoxification. Female sand flies acquire Leishmania with a bloodmeal and the parasites undergo complicated development in their gut finished by the colonization of the stomodeal valve. The PM is one of the most important barriers in Leishmania development and its role in the vector competence of the S. schwetzi is the main topic of this master thesis. The PM's kinetic and morfology in the S. schwetzi is compared with other three sand fly species which differ in susceptibility to L. donovani. The key role of the PM in S. schwetzi vector competence is finally proved by disrupting the PM using the exogenous chitinase from Beauveria bassiana. Under these artificial conditions, the Leishmania parasites (L. donovani and L. major) are able to exit the PM,...
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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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Salivary proteins of sand flies and the immune aspects of Leishmania transmission
Vlková, Michaela ; Volf, Petr (advisor) ; Schwarz, Alexandra (referee) ; Remoue, Franck (referee)
Sand flies serve as the vectors of leishmaniasis and their saliva was shown to affect the outcome of Leishmania infection by immunomodulation of the host. On the other hand, sand fly saliva contains a large scale of farmacologically active proteins that are strongly immunogenous for bitten hosts and specific anti-saliva immunity initiated by repeated sand fly feeding provides protection against Leishmania infection. Specific cell-mediated immunity was shown to be the core of the protectivity; however, our data suggests that the protective immunity has certain limitations. In mice bitten by sand flies for prolonged periods, we observed the desenzitization in term of abrogation of the protective immunity. Thus, we can speculate that the protective effect of immunity is linked solely with the short-term exposure. Nevertheless, our experiments showed that this aspect is also conditioned by the immediate infection after the protective short-term immunization. Taken together, it seems that these limitations may explain the circulation of leishmaniasis in endemic areas, even though humans and animals are frequently immunized by bites of uninfected sand flies. Repeated sand fly feeding on various hosts also promotes production of anti-saliva antibodies that reflect the intensity of exposure. We...
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