Vector competence
Dotaz
Zobrazit nápovědu
Visceral leishmaniasis (VL), the most severe form of the disease, is caused by Leishmania donovani in the Indian sub-continent (ISC). Whole genome sequencing studies revealed that two parasite populations exist in the ISC: a main population named the Core Group (CG) found mostly in the lowlands, and a new, genetically different subpopulation called ISC1. Parasites belonging to the CG were shown to be responsible for the recent epidemics, while the ISC1 variant was originally identified in hilly districts of Nepal and was later on increasingly found in the lowlands. Importantly, the ISC1 and CG isolates differ in their drug susceptibility and virulence signatures, suggesting that ISC1 constitutes an emerging and functionally different variant of L. donovani. In present study we aimed to address the potential of ISC1 transmission by the natural vector of L. donovani in the lowlands, Phlebotomus argentipes. By experimental infection of sand flies with parasites of the different genotypes, we demonstrate that ISC1 and CG strains are developing similarly in P. argentipes, suggesting that P. argentipes is a fully competent vector for ISC1 parasites. Integration of previous and current findings shows thus that ISC1 is a new and different variant of L. donovani, fully adapted to spread in the ISC through the main vector. This information is directly useful for managers of the elimination program. Furthermore, integration of our successive studies (genotyping, phenotyping and vector competence) demonstrates the relevance of molecular surveillance and should be of interest for scientists working on vector borne diseases and control managers.
- MeSH
- fylogeneze MeSH
- hmyz - vektory parazitologie MeSH
- Leishmania donovani klasifikace genetika izolace a purifikace MeSH
- leishmanióza viscerální přenos MeSH
- lidé MeSH
- Phlebotomus parazitologie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Indie MeSH
Ticks and the pathogens they transmit constitute a growing burden for human and animal health worldwide. Vector competence is a component of vectorial capacity and depends on genetic determinants affecting the ability of a vector to transmit a pathogen. These determinants affect traits such as tick-host-pathogen and susceptibility to pathogen infection. Therefore, the elucidation of the mechanisms involved in tick-pathogen interactions that affect vector competence is essential for the identification of molecular drivers for tick-borne diseases. In this review, we provide a comprehensive overview of tick-pathogen molecular interactions for bacteria, viruses, and protozoa affecting human and animal health. Additionally, the impact of tick microbiome on these interactions was considered. Results show that different pathogens evolved similar strategies such as manipulation of the immune response to infect vectors and facilitate multiplication and transmission. Furthermore, some of these strategies may be used by pathogens to infect both tick and mammalian hosts. Identification of interactions that promote tick survival, spread, and pathogen transmission provides the opportunity to disrupt these interactions and lead to a reduction in tick burden and the prevalence of tick-borne diseases. Targeting some of the similar mechanisms used by the pathogens for infection and transmission by ticks may assist in development of preventative strategies against multiple tick-borne diseases.
- MeSH
- arachnida jako vektory mikrobiologie parazitologie virologie MeSH
- interakce hostitele a patogenu * MeSH
- klíšťata mikrobiologie parazitologie fyziologie virologie MeSH
- lidé MeSH
- nemoci přenášené klíšťaty epidemiologie MeSH
- přenos infekční nemoci * MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Zika virus (ZIKV) has spread in the Americas since 2015 and the potential establishment of a sylvatic transmission cycle in the continent has been hypothesized. We evaluated vector competence of five sylvatic Neotropical mosquito species to two ZIKV isolates. Distinct batches of Haemagogus leucoceleanus, Sabethes albiprivus, Sabethes identicus, Aedes terrens and Aedes scapularis females were respectively orally challenged and inoculated intrathoracically with ZIKV. Orally challenged mosquitoes were refractory or exhibited low infection rates. Viral dissemination was detected only in Hg. leucocelaenus, but with very low rates. Virus was not detected in saliva of any mosquito orally challenged with ZIKV, regardless of viral isolate and incubation time. When intrathoracically injected, ZIKV disseminated in high rates in Hg. leucocelaenus, Sa. identicus and Sa. albpiprivus, but low transmission was detected in these species; very low dissemination and no transmission was detected in Ae. terrens and Ae. scapularis. Together these results suggest that genetically determined tissue barriers, especially in the midgut, play a vital role in inhibiting ZIKV for transmission in the tested sylvatic mosquito species. Thus, an independent enzootic transmission cycle for ZIKV in South America is very unlikely.
- MeSH
- infekce přenášené vektorem MeSH
- infekce virem zika diagnóza epidemiologie přenos virologie MeSH
- komáří přenašeči virologie MeSH
- lidé MeSH
- ochrana veřejného zdraví MeSH
- virová nálož MeSH
- virus zika * klasifikace genetika MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Jižní Amerika MeSH
Biting midges of the genus Forcipomyia (Diptera: Ceratopogonidae) have recently been implicated as vectors of kinetoplastid parasites in the Leishmania enrietti complex. This study assesses susceptibility of one of the few successfully colonized Ceratopogonidae, Culicoides nubeculosus Meigen, to infection with Leishmania parasites infecting humans. While Leishmania infantum initially developed in the midgut of C. nubeculosus until 2 d postfeeding, parasite populations on day 3 were considerably reduced. Despite this, a polymerase chain reaction-based assay continued to indicate presence of L. infantum for up to 7 d after the bloodmeal. These findings are discussed within the wider context of implicating arthropods as vectors of Leishmania and it is suggested that conventional polymerase chain reaction use in vector-competence studies should be accompanied by direct microscopical observations.
- MeSH
- feces parazitologie MeSH
- finanční podpora výzkumu jako téma MeSH
- hmyz - vektory parazitologie MeSH
- králíci MeSH
- Leishmania major izolace a purifikace růst a vývoj MeSH
- Leishmania tropica izolace a purifikace růst a vývoj MeSH
- Phlebotomus parazitologie MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- zvířata MeSH
The present concept of the transmission of Lyme disease from Borrelia-infected Ixodes sp. ticks to the naïve host assumes that a low number of spirochetes that manage to penetrate the midgut epithelium migrate through the hemocoel to the salivary glands and subsequently infect the host with the aid of immunomodulatory compounds present in tick saliva. Therefore, humoral and/or cellular immune reactions within the tick hemocoel may play an important role in tick competence to act as a vector for borreliosis. To test this hypothesis we have examined complement-like reactions in the hemolymph of the hard tick Ixodes ricinus against Borrelia afzelii (the most common vector and causative agent of Lyme disease in Europe). We demonstrate that I. ricinus hemolymph does not exhibit borreliacidal effects comparable to complement-mediated lysis of bovine sera. However, after injection of B. afzelii into the tick hemocoel, the spirochetes were efficiently phagocytosed by tick hemocytes and this cellular defense was completely eliminated by pre-injection of latex beads. As tick thioester-containing proteins (T-TEPs) are components of the tick complement system, we performed RNAi-mediated silencing of all nine genes encoding individual T-TEPs followed by in vitro phagocytosis assays. Silencing of two molecules related to the C3 complement component (IrC3-2 and IrC3-3) significantly suppressed phagocytosis of B. afzelii, while knockdown of IrTep (insect type TEP) led to its stimulation. However, RNAi-mediated silencing of T-TEPs or elimination of phagocytosis by injection of latex beads in B. afzelii-infected I. ricinus nymphs had no obvious impact on the transmission of spirochetes to naïve mice, as determined by B. afzelii infection of murine tissues following tick infestation. This result supports the concept that Borrelia spirochetes are capable of avoiding complement-related reactions within the hemocoel of ticks competent to transmit Lyme disease.
- MeSH
- arachnida jako vektory imunologie mikrobiologie MeSH
- Borrelia burgdorferi komplex imunologie MeSH
- fagocytóza * MeSH
- hemocyty imunologie MeSH
- klíště imunologie mikrobiologie MeSH
- komplement metabolismus MeSH
- lymeská nemoc přenos MeSH
- modely nemocí na zvířatech MeSH
- myši MeSH
- přenos infekční nemoci MeSH
- proteiny členovců metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Leishmania infantum is the most widespread etiological agent of visceral leishmaniasis (VL) in the world, with significant mortality rates in human cases. In Latin America, this parasite is primarily transmitted by Lutzomyia longipalpis, but the role of Lutzomyia migonei as a potential vector for this protozoan has been discussed. Laboratory and field investigations have contributed to this hypothesis; however, proof of the vector competence of L. migonei has not yet been provided. In this study, we evaluate for the first time the susceptibility of L. migonei to L. infantum. METHODS: Females of laboratory-reared L. migonei were fed through a chick-skin membrane on rabbit blood containing L. infantum promastigotes, dissected at 1, 5 and 8 days post-infection (PI) and checked microscopically for the presence, intensity and localisation of Leishmania infections. In addition, morphometric analysis of L. infantum promastigotes was performed. RESULTS: High infection rates of both L. infantum strains tested were observed in L. migonei, with colonisation of the stomodeal valve already on day 5 PI. At the late-stage infection, most L. migonei females had their cardia and stomodeal valve colonised by high numbers of parasites, and no significant differences were found compared to the development in L. longipalpis. Metacyclic forms were found in all parasite-vector combinations since day 5 PI. CONCLUSIONS: We propose that Lutzomyia migonei belongs to sand fly species permissive to various Leishmania spp. Here we demonstrate that L. migonei is highly susceptible to the development of L. infantum. This, together with its known anthropophily, abundance in VL foci and natural infection by L. infantum, constitute important evidence that L. migonei is another vector of this parasite in Latin America.
A prerequisite for possible autochthonous transmission of the Zika virus in Europe would be the presence of a competent mosquito species of the genus Aedes. The Aedes aegypti mosquito has been recognized worldwide as a Zika virus vector, and the Asian tiger mosquito (Aedes albopictus) is considered as a potential alternative vector. In Europe, Aedes aegypti is only present on the Madeira island and locally along the east coast of the Black Sea. However, Aedes albopictus is abundant in nearly all Mediterranean countries, southern Switzerland, and in the Balkans. The key question is as follows: Are the European populations of Aedes albopictus competent for Zika virus transmission?
Pro případný autochtonní přenos viru Zika v Evropském regionu je nutná přítomnost kompetentního komářího přenašeče (vektor) rodu Aedes. Celosvětově je komár tropický (Aedes aegypti) prokázaný přenašeč viru Zika, komár tygrovaný (Aedes albopictus) je považován za pravděpodobného alternativního přenašeče. Výskyt Ae. aegypti v Evropě je omezen na ostrov Madeira a okrskově na východní pobřeží Černého moře. Avšak Ae. albopictus se vyskytuje, mnohdy velmi hojně, prakticky ve všech středomořských státech, v jižním Švýcarsku a na Balkáně. Klíčová otázka zní: jsou evropské populace Ae. albopictus schopny přenést virus Zika?
- Klíčová slova
- komár tropický, komár tygrovaný, Aedes aegypti, Aedes albopictus,
- MeSH
- Aedes * MeSH
- Flaviviridae * MeSH
- hmyz - vektory * MeSH
- infekce viry z čeledi Flaviviridae přenos MeSH
- virus zika MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Geografické názvy
- Evropa MeSH
Verifying the speaker of a speech fragment can be crucial in attributing a crime to a suspect. The question can be addressed given disputed and reference speech material, adopting the recommended and scientifically accepted likelihood ratio framework for reporting evidential strength in court. In forensic practice, usually, auditory and acoustic analyses are performed to carry out such a verification task considering a diversity of features, such as language competence, pronunciation, or other linguistic features. Automated speaker comparison systems can also be used alongside those manual analyses. State-of-the-art automatic speaker comparison systems are based on deep neural networks that take acoustic features as input. Additional information, though, may be obtained from linguistic analysis. In this paper, we aim to answer if, when and how modern acoustic-based systems can be complemented by an authorship technique based on frequent words, within the likelihood ratio framework. We consider three different approaches to derive a combined likelihood ratio: using a support vector machine algorithm, fitting bivariate normal distributions, and passing the score of the acoustic system as additional input to the frequent-word analysis. We apply our method to the forensically relevant dataset FRIDA and the FISHER corpus, and we explore under which conditions fusion is valuable. We evaluate our results in terms of log likelihood ratio cost (Cllr) and equal error rate (EER). We show that fusion can be beneficial, especially in the case of intercepted phone calls with noise in the background.
- MeSH
- akustika řeči MeSH
- algoritmy MeSH
- lidé MeSH
- lingvistika MeSH
- pravděpodobnostní funkce MeSH
- řeč MeSH
- soudní vědy * metody MeSH
- support vector machine MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Cutaneous leishmaniasis caused by Leishmania major is a typical zoonosis circulating in rodents. In Sub-Saharan Africa the reservoirs remain to be identified, although L. major has been detected in several rodent species including members of the genera Arvicanthis and Mastomys. However, differentiation of true reservoir hosts from incidental hosts requires in-depth studies both in the field and in the laboratory, with the best method for testing the infectiousness of hosts to biting vectors being xenodiagnosis. Here we studied experimental infections of three L. major strains in Arvicanthis neumanni, A. niloticus and Mastomys natalensis; the infections were initiated either with sand fly-derived or with culture-derived Leishmania promastigotes. Inoculated rodents were monitored for several months and tested by xenodiagnoses for their infectiousness to Phlebotomus duboscqi, the natural vector of L. major in Sub-Saharan Africa. The distribution and load of parasites were determined post mortem using qPCR from the blood, skin and viscera samples. The attractiveness of Arvicanthis and Mastomys to P. duboscqi was tested by pair-wise comparisons. Three L. major strains used significantly differed in infectivity: the Middle Eastern strain infected a low proportion of rodents, while two Sub-Saharan isolates (LV109, LV110) infected a high percentage of animals and LV110 also produced higher parasite loads in all host species. All three rodent species maintained parasites of the LV109 strain for 20-25 weeks and were able to infect P. duboscqi without apparent health complications: infected animals showed only temporary swellings or changes of pigmentation at the site of inoculation. However, the higher infection rates, more generalized distribution of parasites and longer infectiousness period to sand flies in M. natalensis suggest that this species plays the more important reservoir role in the life cycle of L. major in Sub-Saharan Africa. Arvicanthis species may serve as potential reservoirs in seasons/periods of low abundance of Mastomys.
- Publikační typ
- časopisecké články MeSH
