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Sauroleishmania-sand fly interactions
Tichá, Lucie ; Volf, Petr (advisor) ; Berriatua Fernández de Larea, Eduardo (referee) ; Shaw, Jeffrey Jon (referee)
Sauroleishmania is a group of less studied parasites that belong to the genus Leishmania (Kinetoplastida: Trypanosomatidae). They circulate between reptile hosts and sand fly vectors (Diptera: Psychodidae). Due to the non-pathogenic character of its species, little is known about their development in reptiles and sand flies. The main objective of this project was to elucidate some missing aspects of Sauroleishmania life cycle. A major part of this thesis aimed to test the susceptibility of various sand fly species to different Sauroleishmania isolates and describe their development in the sand fly intestinal tract. A minor part was devoted to the study of infection in reptiles. First, we investigated the development of Leishmania (Sauroleishmania) tarentolae in three Phlebotomus species. Sand flies were infected through membrane on promastigote suspension and dissected at various time intervals post infection. Leishmania (S.) tarentolae developed in all three species tested and underwent peripylarian type of the development. Moreover, heavy parasite loads were frequently found in Malpighian tubules, which is a unique localization among Leishmania parasites. To summarize the current knowledge on L. (S.) tarentolae, we have also written a review describing the origin, life cycle and application of...
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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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The immune response in Post-kala-azar dermal leishmaniasis (PKDL)
Záluská, Elisabeth ; Volf, Petr (advisor) ; Leštinová, Tereza (referee)
Visceral leishmaniasis (VL), also called kala-azar, is a life-threatening parasitic disease, most often caused by Leishmania donovani. After recovery from VL, parasites persisting in the skin can cause post kala-azar dermatitis (PKDL). PKDL is found mainly in the Indian subcontinent and East Africa. Patients with PKDL are a threat to public health and their surroundings because they can serve as a reservoir for the parasite and thus help in its further spread. PKDL has two main forms: in South Asia are mostly caused by papulonodular lesions (pimples and bumps on the skin surface). In East Africa are more common hypomelatonic lesions (hypopigmentation of the skin, characterized by light spots). In patients, there is a decrease in the expression of melanin-A and a gradual loss and degeneration of melanocytes. After an episode of VL, there is a different immune response in the skin and in the rest of the body. The immune response is somewhere between TH1 and TH2, and that gives an advantage to the remaining surviving parasites in the skin. The TH1 response is responsible for the inflammatory response and formation of skin lesions, which are typical for PKDL. On the other hand, the TH2 response promotes regeneration and healing process, and that helps the parasite persist in the skin. For the...
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Development of Asaia genus in sand flies and its impact on Leishmania transmission
Stejskalová, Markéta ; Jančářová, Magdaléna (advisor) ; Procházková, Petra (referee)
The composition of the microbiome of insect vectors plays an irreplaceable role in the spread of human pathogens. Current knowledge of the interrelationships between phlebo- tomes, bacteria, and pathogens is quite limited. This thesis focuses on bacterias Asaia sp., which can be localized in a phlebotome microbiome. Both investigated species, Asaia siamensis and Asaia krungthepensis, can colo- nize the gut of Phlebotomus duboscqi, and, in addition, both transstadial transmission between larval stages and contaminative transmission to the next generation has been proved. Considering the superinfection of Ph. duboscqi with Asaia sp. and Leishmania major, the influence of bacteria on the development of leishmania infection has also been demonstrated. Results can have significant epidemiological implications and should be further investigated. Keywords: Phlebotomus, superinfection, Asaia siamensis, Asaia krungthepensis, Leishma- nia major, microbiome 1
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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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Comparison of different rodent species as hosts of human pathogenic leishmania.
Vojtková, Barbora
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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Sex chromosomes of Nematocera
Ryšan, Tadeáš ; Volf, Petr (advisor) ; Šťáhlavský, František (referee)
The paraphyletic group Nematocera is highly diversified in both body morphology and life strategies. Based on sex chromosome morphology, it can be divided into four groups defined as early as the mid- 20th century. All these systems are based on the presence of the XY/XX sex chromosomes or the loss of the Y chromosome. The different groups are distinguished based on whether the chromosomes are differentiated, whether chiasmata are present and whether the Y chromosome is retained. However, later research has shown much higher sex chromosome diversity, mostly in groups with homomorphic gonosomes. Even though most representatives of this group do not have differentiated sex chromosomes, we find the recurrence of differentiated gonosomes and even the X1X2Y1Y2/ X1X1X2X2 and ZW/ZZ sex systems, which are less typical for Diptera. These findings suggest that the form of sex chromosomes in Diptera may not be as stable as previously thought. The recently discovered non- homology of gonosomes across the Diptera, including several representatives of Nematocera, supports this idea. Multiple independent gonosome formation could also explain the diversity of primary sex- determining factors in those groups where these factors are known. Key words: Nematocera, Phlebotomus, Lutzomyia, sex chromosomes, sex determination
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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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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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Immunity in hosts repeatedly exposed to sand fies and the effect on pathogen transmission
Pohanková, Lucia ; Kolářová, Iva (advisor) ; Fialová, Anna (referee)
6 Abstrakt During the feeding of infected sand flies are inoculate into the host also sand fly saliva, which can strongly modulate the response of the immune system. If the host is naive, the course of infection is usually worse. In cutaneous leishmaniasis, the lesions developed early, are more destructive and persist longer. The hosts living in endemic areas of leishamniasis and their vector hosts are often exposed to feeding uninfected sand flies. For host are the saliva antigenic and induces specific cellular and antibody responses. This responses induce the protection against leishmania infection and differ for different hosts, attempts were made most frequently in murine and canine models. In humans, as hosts is difficult to monitor developments leishmania infection after previous exposure, because in humans mainly monitors the levels of antibodies, by which we can determine the degree of sand fly bites and the risk of transmission of leishmaniasis. Keywords: Lutzomyia, Phlebotomus, DTH, antibody, IgG,
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