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EMBO Reports Mar 2024Leishmania parasites undergo differentiation between various proliferating and non-dividing forms to adapt to changing host environments. The mechanisms that link...
Leishmania parasites undergo differentiation between various proliferating and non-dividing forms to adapt to changing host environments. The mechanisms that link environmental cues with the parasite's developmental changes remain elusive. Here, we report that Leishmania TORC1 is a key environmental sensor for parasite proliferation and differentiation in the sand fly-stage promastigotes and for replication of mammalian-stage amastigotes. We show that Leishmania RPTOR1, interacts with TOR1 and LST8, and identify new parasite-specific proteins that interact in this complex. We investigate TORC1 function by conditional deletion of RPTOR1, where under nutrient-rich conditions RPTOR1 depletion results in decreased protein synthesis and growth, G1 cell cycle arrest and premature differentiation from proliferative promastigotes to non-dividing mammalian-infective metacyclic forms. These parasites are unable to respond to nutrients to differentiate into proliferative retroleptomonads, which are required for their blood-meal induced amplification in sand flies and enhanced mammalian infectivity. We additionally show that RPTOR1 metacyclic promastigotes develop into amastigotes but do not proliferate in the mammalian host to cause pathology. RPTOR1-dependent TORC1 functionality represents a critical mechanism for driving parasite growth and proliferation.
Topics: Animals; Leishmania; Psychodidae; Phlebotomus; Nutrients; Cell Proliferation; Mammals
PubMed: 38396206
DOI: 10.1038/s44319-024-00084-y -
PloS One 2022Morphological characteristics of eggshells are important in sand fly ootaxonomy. In this study, eggshells from Phlebotomus stantoni Newstead, Sergentomyia khawi...
Morphological characteristics of eggshells are important in sand fly ootaxonomy. In this study, eggshells from Phlebotomus stantoni Newstead, Sergentomyia khawi (Raynal), and Grassomyia indica (Theodor) sand flies collected in Chiang Mai province, Thailand were examined and characterized using light microscopy (LM) and scanning electron microscopy (SEM). Then, eggshell morphology of these three species was described for the first time. Each gravid female was forced to lay eggs by decapitation and the eggs were collected for SEM analysis. Egg laying females were identified by morphological examination and molecular typing using cytochrome b (Cytb) as a molecular marker. The chorionic sculpturing of Ph. stantoni eggs combines two patterns on the same egg: unconnected parallel ridges and reticular patterns. Sergentomyia khawi and Gr. indica have similar chorionic polygonal patterns, but their exochorionic morphology and aeropylar area are different. Results indicate that eggshell morphological characteristics such as chorionic pattern, exochorionic morphology, inter-ridge/boundary area, aeropylar area (including the number of aeropyles) and basal layer, can be useful to develop morphological identification keys of eggs. These can serve as an additional tool to distinguish species of sand flies. In addition, the chorionic sculpturing of the eggs of the three species of sand flies observed by LM is useful for species identification in gravid females with spermathecae obscured by eggs.
Topics: Animals; Chorion; Cytochromes b; Egg Shell; Eggs; Female; Microscopy, Electron, Scanning; Oviposition; Psychodidae; Species Specificity
PubMed: 35213563
DOI: 10.1371/journal.pone.0263268 -
Journal of Medical Entomology Sep 2015Chemical insecticides are effective for controlling Lutzomyia and Phlebotomus sand fly (Diptera: Psychodidae) vectors of Leishmania parasites. However, repeated use of...
Chemical insecticides are effective for controlling Lutzomyia and Phlebotomus sand fly (Diptera: Psychodidae) vectors of Leishmania parasites. However, repeated use of certain insecticides has led to tolerance and resistance. The objective of this study was to determine lethal concentrations (LCs) and lethal exposure times (LTs) to assess levels of susceptibility of laboratory Lutzomyia longipalpis (Lutz and Nieva) and Phlebotomus papatasi (Scopoli) to 10 insecticides using a modified version of the World Health Organization (WHO) exposure kit assay and Centers for Disease Control and Prevention (CDC) bottle bioassay. Sand flies were exposed to insecticides coated on the interior of 0.5-gallon and 1,000-ml glass bottles. Following exposure, the flies were allowed to recover for 24 h, after which mortality was recorded. From dose-response survival curves for L. longipalpis and P. papatasi generated with the QCal software, LCs causing 50, 90, and 95% mortality were determined for each insecticide. The LCs and LTs from this study will be useful as baseline reference points for future studies using the CDC bottle bioassays to assess insecticide susceptibility of sand fly populations in the field. There is a need for a larger repository of sand fly insecticide susceptibility data from the CDC bottle bioassays, including a range of LCs and LTs for more sand fly species with more insecticides. Such a repository would be a valuable tool for vector management.
Topics: Animals; Dose-Response Relationship, Drug; Insecticide Resistance; Insecticides; Lethal Dose 50; Phlebotomus; Psychodidae
PubMed: 26336231
DOI: 10.1093/jme/tjv091 -
Memorias Do Instituto Oswaldo Cruz Feb 2014The composition and seasonal occurrence of sandflies were investigated in coffee agroecosystems in the Soconusco region of Chiapas, Mexico. Insect sampling was performed...
The composition and seasonal occurrence of sandflies were investigated in coffee agroecosystems in the Soconusco region of Chiapas, Mexico. Insect sampling was performed on three plantations located at different altitudes: Finca Guadalupe Zajú [1,000 m above sea level (a.s.l.)], Finca Argovia (613 m a.s.l.) and Teotihuacán del Valle (429 m a.s.l.). Sandflies were sampled monthly from August 2007-July 2008 using three sampling methods: Shannon traps, CDC miniature light traps and Disney traps. Sampling was conducted for 3 h during three consecutive nights, beginning at sunset. A total of 4,387 sandflies were collected during the course of the study: 2,718 individuals in Finca Guadalupe Zajú, 605 in Finca Argovia and 1,064 in Teotihuacán del Valle. The Shannon traps captured 94.3% of the total sandflies, while the CDC light traps and Disney traps captured 4.9% and 0.8%, respectively. More females than males were collected at all sites. While the number of sandflies captured was positively correlated with temperature and relative humidity, a negative correlation was observed between sandfly numbers and rainfall. Five species of sandflies were captured: Lutzomyia cruciata , Lutzomyia texana , Lutzomyia ovallesi , Lutzomyia cratifer / undulata and Brumptomyia sp. Lu. cruciata , constituting 98.8% of the total, was the most abundant species. None of the captured sandflies was infected with Leishmania spp.
Topics: Animal Distribution; Animals; Coffea; Crops, Agricultural; Ecosystem; Female; Humidity; Insect Vectors; Leishmania; Male; Mexico; Psychodidae; Seasons; Sex Distribution; Temperature
PubMed: 24271002
DOI: 10.1590/0074-0276130224 -
Journal of the American Mosquito... Sep 2008Phlebotomine sand flies are vectors of bacteria, parasites, and viruses. Lutzomyia apache, a North American sand fly, was incriminated as a vector of vesicular...
Phlebotomine sand flies are vectors of bacteria, parasites, and viruses. Lutzomyia apache, a North American sand fly, was incriminated as a vector of vesicular stomatitis viruses (VSV) due to overlapping ranges of the sand fly and recent outbreaks of VSV. We report on the discovery of 2 populations of L. apache in Wyoming from Albany and Fremont counties. We attempted to isolate VSV and phleboviruses from sand flies from Albany County and screened select flies by polymerase chain reaction for Bartonella and blood meals. We did not isolate viruses or detect DNA from vertebrate hosts or Bartonella. Flies were also tested for insect pathogens and other microbes. We detected a Rickettsia sp. in all flies that were examined and a parasitic protozoon, Ascogregarina sp., from the midgut of a larva. Eustigmaeus lirella, a stigmaeid mite, parasitized 2 field-caught females.
Topics: Animals; Female; Insect Vectors; Male; Pest Control, Biological; Psychodidae; Wyoming
PubMed: 18939699
DOI: 10.2987/5745.1 -
PLoS Neglected Tropical Diseases Apr 2022It is well-known that Leishmania parasites can alter the behavior of the sand fly vector in order to increase their transmission potential. However, little is known...
It is well-known that Leishmania parasites can alter the behavior of the sand fly vector in order to increase their transmission potential. However, little is known about the contribution of the infecting host's blood composition on subsequent sand fly infection and survival. This study focused on the host's glucose metabolism and the insulin/insulin-like growth factor 1 (IGF-1) pathway as both metabolic processes are known to impact vector-parasite interactions of other protozoa and insect species. The focus of this study was inspired by the observation that the glycemic levels in the blood of infected Syrian golden hamsters inversely correlated to splenic and hepatic parasite burdens. To evaluate the biological impact of these findings on further transmission, Lutzomyia longipalpis sand flies were infected with blood that was artificially supplemented with different physiological concentrations of several monosaccharides, insulin or IGF-1. Normoglycemic levels resulted in transiently higher parasite loads and faster appearance of metacyclics, whereas higher carbohydrate and insulin/IGF-1 levels favored sand fly survival. Although the recorded effects were modest or transient of nature, these observations support the concept that the host blood biochemistry may affect Leishmania transmission and sand fly longevity.
Topics: Animals; Cricetinae; Insulin; Insulin-Like Growth Factor I; Leishmania infantum; Phlebotomus; Psychodidae; Sugars
PubMed: 35385472
DOI: 10.1371/journal.pntd.0010293 -
Journal of Vector Ecology : Journal of... Jun 2013An entomological study was conducted from June to September, 2010 in rural regions of Azarbayjan-e-sharqi, Azarbayjan-e-qarbi, and Ardabil provinces in northwestern Iran...
An entomological study was conducted from June to September, 2010 in rural regions of Azarbayjan-e-sharqi, Azarbayjan-e-qarbi, and Ardabil provinces in northwestern Iran to determine sand fly fauna, diversity, and distribution in different habitats and altitudes using both sticky papers and light traps. Geographical distribution of sand flies and the similarity of populations in different locations were analyzed ecologically based on the Shannon-Wiener Index and Jacard Coefficient, respectively. A total of 3,982 specimens was collected and sixteen species recorded. They belonged to the genera Phlebotomus [subgenus Phlebotomus (P. papatasi), Paraphlebotomus (P. sergenti, P. mongolensis, P. caucasicus, P. jacusieli), Larroussius (P. major s.l., P. tobbi, P. perfiliewi transcaucasicus, P. kandelakii) and Adlerius (P. halepensis, P. brevis, P. longiductus, P. balcanicus)], and Sergentomyia [subgenus Sergentomyia (S. sintoni, S. dentata and S. theodori)]. P. papatasi was the predominant species in all the locations except Bileh Savar, Macu, and Meshkin Shahr, followed by P. perfiliewi transcaucasicus and P. kandelakii. The latter species were caught from different habitats and altitudes with higher frequency than other species of the subgenus Larroussius. The lowest abundance belonged to P. jacusieli. The predominant species of subgenus Adlerius was P. halepensis. Data analysis showed that Meshkin Shahr and Bileh Savar had high and low diversities of sand fly distribution, respectively. Meshkin Shahr and Sarab districts had the highest similarity. Both are located in the foothills of Sabalan Mountain, with high diversity and richness.
Topics: Altitude; Animals; Biodiversity; Iran; Leishmaniasis, Visceral; Psychodidae
PubMed: 23701613
DOI: 10.1111/j.1948-7134.2013.12014.x -
Frontiers in Cellular and Infection... 2019Despite the increasing number of studies concerning insect immunity, immune responses in the presence of infection has not been widely investigated. The few available...
Despite the increasing number of studies concerning insect immunity, immune responses in the presence of infection has not been widely investigated. The few available studies analyzed the role of the Toll and IMD pathways involved in response against and microbial infections. Nevertheless, effector molecules responsible for controlling sand fly infections have not been identified. In the present study we investigated the role a signal transduction pathway, the Transforming Growth Factor-beta (TGF-β) pathway, on the interrelation between and . We identified an homolog belonging to the multifunctional cytokine TGF-β gene family (-β), which is closely related to the activin/inhibin subfamily and potentially involved in responses to infections. We investigated this gene expression through the insect development and in adult flies infected with . Our results showed that -β was expressed in all developmental stages and was upregulated at the third day post infection, when protein levels were also higher as compared to uninfected insects. At this point blood digestion is finished and parasites are in close contact with the insect gut. In addition, we investigated the role of LlTGF-β on infection by using either gene silencing by RNAi or pathway inactivation by addition of the TGF-β receptor inhibitor SB431542. The blockage of the LlTGF-β pathway increased significantly antimicrobial peptides expression and nitric oxide levels in the insect gut, as expected. Both methods led to a decreased infection. Our results show that inactivation of the TGF-β signal transduction pathway reduce survival, therefore suggesting that under natural conditions the parasite benefits from the insect LlTGF-β pathway, as already seen in infection of mosquitoes.
Topics: Animals; Gene Expression Profiling; Host-Pathogen Interactions; Immunity, Innate; Insect Vectors; Leishmania infantum; Psychodidae; Signal Transduction; Survival Analysis; Transforming Growth Factor beta
PubMed: 30972305
DOI: 10.3389/fcimb.2019.00071 -
Memorias Do Instituto Oswaldo Cruz Feb 2018BACKGROUND The insect chitinase gene family is composed by more than 10 paralogs, which can codify proteins with different domain structures. In Lutzomyia longipalpis,...
BACKGROUND The insect chitinase gene family is composed by more than 10 paralogs, which can codify proteins with different domain structures. In Lutzomyia longipalpis, the main vector of visceral leishmaniasis in Brazil, a chitinase cDNA from adult female insects was previously characterized. The predicted protein contains one catalytic domain and one chitin-binding domain (CBD). The expression of this gene coincided with the end of blood digestion indicating a putative role in peritrophic matrix degradation. OBJECTIVES To determine the occurrence of alternative splicing in chitinases of L. longipalpis. METHODS We sequenced the LlChit1 gene from a genomic clone and the three spliced forms obtained by reverse transcription polymerase chain reaction (RT-PCR) using larvae cDNA. FINDINGS We showed that LlChit1 from L. longipalpis immature forms undergoes alternative splicing. The spliced form corresponding to the adult cDNA was named LlChit1A and the two larvae specific transcripts were named LlChit1B and LlChit1C. The B and C forms possess stop codons interrupting the translation of the CBD. The A form is present in adult females post blood meal, L4 larvae and pre-pupae, while the other two forms are present only in L4 larvae and disappear just before pupation. Two bands of the expected size were identified by Western blot only in L4 larvae. MAIN CONCLUSIONS We show for the first time alternative splicing generating chitinases with different domain structures increasing our understanding on the finely regulated digestion physiology and shedding light on a potential target for controlling L. longipalpis larval development.
Topics: Alternative Splicing; Animals; Chitinases; Digestive System; Female; Phylogeny; Psychodidae; Reverse Transcriptase Polymerase Chain Reaction
PubMed: 29236932
DOI: 10.1590/0074-02760170179 -
Parasites & Vectors Mar 2016Leishmania infantum is the most widespread etiological agent of visceral leishmaniasis (VL) in the world, with significant mortality rates in human cases. In Latin...
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.
Topics: Animals; Insect Vectors; Leishmania infantum; Microscopy; Psychodidae
PubMed: 26988559
DOI: 10.1186/s13071-016-1444-2