共查询到20条相似文献,搜索用时 31 毫秒
1.
Susana Carolina Martins Ferreira Heribert Hofer Luis Madeira de Carvalho Marion L. East 《Ecology and evolution》2019,9(15):8783-8799
There are substantial individual differences in parasite composition and infection load in wildlife populations. Few studies have investigated the factors shaping this heterogeneity in large wild mammals or the impact of parasite infections on Darwinian fitness, particularly in juveniles. A host's parasite composition and infection load can be shaped by factors that determine contact with infective parasite stages and those that determine the host's resistance to infection, such as abiotic and social environmental factors, and age. Host–parasite interactions and synergies between coinfecting parasites may also be important. We test predictions derived from these different processes to investigate factors shaping infection loads (fecal egg/oocyte load) of two energetically costly gastrointestinal parasites: the hookworm Ancylostoma and the intracellular Cystoisospora, in juvenile spotted hyenas (Crocuta crocuta) in the Serengeti National Park, in Tanzania. We also assess whether parasite infections curtail survival to adulthood and longevity. Ancylostoma and Cystoisospora infection loads declined as the number of adult clan members increased, a result consistent with an encounter‐reduction effect whereby adults reduced encounters between juveniles and infective larvae, but were not affected by the number of juveniles in a clan. Infection loads decreased with age, possibly because active immune responses to infection improved with age. Differences in parasite load between clans possibly indicate variation in abiotic environmental factors between clan den sites. The survival of juveniles (<365 days old) to adulthood decreased with Ancylostoma load, increased with age, and was modulated by maternal social status. High‐ranking individuals with low Ancylostoma loads had a higher survivorship during the first 4 years of life than high‐ranking individuals with high Ancylostoma loads. These findings suggest that high infection loads with energetically costly parasites such as hookworms during early life can have negative fitness consequences. 相似文献
2.
Hideo Hasegawa David Modry Masahiro Kitagawa Kathryn A. Shutt Angelique Todd Barbora Kalousová Ilona Profousová Klára J. Petr?elková 《PLoS neglected tropical diseases》2014,8(3)
Background
Hookworms are important pathogens of humans. To date, Necator americanus is the sole, known species of the genus Necator infecting humans. In contrast, several Necator species have been described in African great apes and other primates. It has not yet been determined whether primate-originating Necator species are also parasitic in humans.Methodology/Principal Findings
The infective larvae of Necator spp. were developed using modified Harada-Mori filter-paper cultures from faeces of humans and great apes inhabiting Dzanga-Sangha Protected Areas, Central African Republic. The first and second internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA and partial cytochrome c oxidase subunit 1 (cox1) gene of mtDNA obtained from the hookworm larvae were sequenced and compared. Three sequence types (I–III) were recognized in the ITS region, and 34 cox1 haplotypes represented three phylogenetic groups (A–C). The combinations determined were I-A, II-B, II-C, III-B and III-C. Combination I-A, corresponding to N. americanus, was demonstrated in humans and western lowland gorillas; II-B and II-C were observed in humans, western lowland gorillas and chimpanzees; III-B and III-C were found only in humans. Pairwise nucleotide difference in the cox1 haplotypes between the groups was more than 8%, while the difference within each group was less than 2.1%.Conclusions/Significance
The distinctness of ITS sequence variants and high number of pairwise nucleotide differences among cox1 variants indicate the possible presence of several species of Necator in both humans and great apes. We conclude that Necator hookworms are shared by humans and great apes co-habiting the same tropical forest ecosystems. 相似文献3.
Taehee Chang Bong-Kwang Jung Woon-Mok Sohn Sooji Hong Hyejoo Shin Seungwan Ryoo Jeonggyu Lee Keon Hoon Lee Virak Khieu Rekol Huy Jong-Yil Chai 《The Korean journal of parasitology》2020,58(6):619
Human hookworm infections caused by adult Ancylostoma spp. and Necator americanus are one of the most important tropical diseases. We performed a survey of intestinal helminths using the Kato-Katz fecal examination technique targeting 1,156 villagers residing in 2 northern provinces (Preah Vihear and Stung Treng) of Cambodia in 2018. The results revealed a high overall egg positive rate of intestinal helminths (61.9%), and the egg positive rate of hookworms was 11.6%. Nine of the hookworm egg positive cases in Preah Vihear Province were treated with 5–10 mg/kg pyrantel pamoate followed by purging with magnesium salts, and a total of 65 adult hookworms were expelled in diarrheic stools. The adult hookworms were analyzed morphologically and molecularly to confirm the species. The morphologies of the buccal cavity and dorsal rays on the costa were observed with a light microscope, and the nucleotide sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) gene were analyzed. The majority of the hookworm adults (90.7%) were N. americanus, whereas the remaining 9.3% were Ancylostoma ceylanicum, a rare hookworm species infecting humans. The results revealed a high prevalence of hookworm infections among people in a northern part of Cambodia, suggesting the necessity of a sustained survey combined with control measures against hookworm infections. 相似文献
4.
Stacey Llewellyn Tawin Inpankaew Susana Vaz Nery Darren J. Gray Jaco J. Verweij Archie C. A. Clements Santina J. Gomes Rebecca Traub James S. McCarthy 《PLoS neglected tropical diseases》2016,10(1)
Background
Accurate quantitative assessment of infection with soil transmitted helminths and protozoa is key to the interpretation of epidemiologic studies of these parasites, as well as for monitoring large scale treatment efficacy and effectiveness studies. As morbidity and transmission of helminth infections are directly related to both the prevalence and intensity of infection, there is particular need for improved techniques for assessment of infection intensity for both purposes. The current study aimed to evaluate two multiplex PCR assays to determine prevalence and intensity of intestinal parasite infections, and compare them to standard microscopy.Methodology/Principal Findings
Faecal samples were collected from a total of 680 people, originating from rural communities in Timor-Leste (467 samples) and Cambodia (213 samples). DNA was extracted from stool samples and subject to two multiplex real-time PCR reactions the first targeting: Necator americanus, Ancylostoma spp., Ascaris spp., and Trichuris trichiura; and the second Entamoeba histolytica, Cryptosporidium spp., Giardia. duodenalis, and Strongyloides stercoralis. Samples were also subject to sodium nitrate flotation for identification and quantification of STH eggs, and zinc sulphate centrifugal flotation for detection of protozoan parasites. Higher parasite prevalence was detected by multiplex PCR (hookworms 2.9 times higher, Ascaris 1.2, Giardia 1.6, along with superior polyparasitism detection with this effect magnified as the number of parasites present increased (one: 40.2% vs. 38.1%, two: 30.9% vs. 12.9%, three: 7.6% vs. 0.4%, four: 0.4% vs. 0%). Although, all STH positive samples were low intensity infections by microscopy as defined by WHO guidelines the DNA-load detected by multiplex PCR suggested higher intensity infections.Conclusions/Significance
Multiplex PCR, in addition to superior sensitivity, enabled more accurate determination of infection intensity for Ascaris, hookworms and Giardia compared to microscopy, especially in samples exhibiting polyparasitism. The superior performance of multiplex PCR to detect polyparasitism and more accurately determine infection intensity suggests that it is a more appropriate technique for use in epidemiologic studies and for monitoring large-scale intervention trials. 相似文献5.
Background
Dogs are the most common pet animals worldwide. They may harbour a wide range of parasites with zoonotic potential, thus causing a health risk to humans. In Nigeria, epidemiological knowledge on these parasites is limited.Methods
In a community-based study, we examined 396 dogs in urban and rural areas of Ilorin (Kwara State, Central Nigeria) for ectoparasites and intestinal helminths. In addition, a questionnaire regarding knowledge and practices was applied to pet owners.Results
Nine ectoparasite species belonging to four taxa and six intestinal helminth species were identified: fleas (Ctenocephalides canis, Pulex irritans, Tunga penetrans), mites (Demodex canis, Otodectes sp., Sarcoptes scabiei var. canis), ticks (Rhipicephalus sanguineus, Ixodes sp.), and lice (Trichodectes canis); and Toxocara canis, Ancylostoma sp., Trichuris vulpis, Dipylidium caninum, Taenidae and Strongyloides sp. Overall prevalence of ectoparasites was 60.4% and of intestinal helminths 68.4%. The occurrence of C. canis, R. sanguineus, T. canis, Ancylostoma sp. and T. vulpis was most common (prevalence 14.4% to 41.7%). Prevalence patterns in helminths were age-dependent, with T. canis showing a decreasing prevalence with age of host, and a reverse trend in other parasite species. Knowledge regarding zoonoses was very limited and the diseases not considered a major health problem. Treatment with antiparasitic drugs was more frequent in urban areas.Conclusion
Parasites of importance for human health were highly prevalent in Nigerian dogs. Interventions should include health education provided to dog owners and the establishment of a program focusing on zoonotic diseases.6.
7.
8.
Taylor B. Smallwood Severine Navarro Ben Cristofori-Armstrong Thomas S. Watkins Katie Tungatt Rachael Y.M. Ryan Oscar L. Haigh Viviana P. Lutzky Jason P. Mulvenna K. Johan Rosengren Alex Loukas John J. Miles Richard J. Clark 《The Journal of biological chemistry》2021,297(1)
The prevalence of autoimmune diseases is on the rise globally. Currently, autoimmunity presents in over 100 different forms and affects around 9% of the world’s population. Current treatments available for autoimmune diseases are inadequate, expensive, and tend to focus on symptom management rather than cure. Clinical trials have shown that live helminthic therapy can decrease chronic inflammation associated with inflammatory bowel disease and other gastrointestinal autoimmune inflammatory conditions. As an alternative and better controlled approach to live infection, we have identified and characterized two peptides, Acan1 and Nak1, from the excretory/secretory component of parasitic hookworms for their therapeutic activity on experimental colitis. We synthesized Acan1 and Nak1 peptides from the Ancylostoma caninum and Necator americanus hookworms and assessed their structures and protective properties in human cell–based assays and in a mouse model of acute colitis. Acan1 and Nak1 displayed anticolitic properties via significantly reducing weight loss and colon atrophy, edema, ulceration, and necrosis in 2,4,6-trinitrobenzene sulfonic acid–exposed mice. These hookworm peptides prevented mucosal loss of goblet cells and preserved intestinal architecture. Acan1 upregulated genes responsible for the repair and restitution of ulcerated epithelium, whereas Nak1 downregulated genes responsible for epithelial cell migration and apoptotic cell signaling within the colon. These peptides were nontoxic and displayed key immunomodulatory functions in human peripheral blood mononuclear cells by suppressing CD4+ T cell proliferation and inhibiting IL-2 and TNF production. We conclude that Acan1 and Nak1 warrant further development as therapeutics for the treatment of autoimmunity, particularly gastrointestinal inflammatory conditions. 相似文献
9.
《Revista iberoamericana de micología》2014,31(2):114-118
BackgroundGeohelminths are parasites that stand out for their prevalence and wide distribution, depending on the soil for their transmission.AimsThe aim of this work was to evaluate the predatory capacity of the fungal isolate of the genus Duddingtonia (CG768) on third stage larvae (L3) of Ancylostoma spp. in beach sand under laboratory conditions.MethodsIn the assay A five treatment groups and 1 control group were formed. The treatment groups contained 5000, 10,000, 15,000, 20,000 or 25,000 chlamydospores of the fungal isolate and 1000 Ancylostoma spp. L3 in pots containing 30 g of sand. The control group (without fungus) contained only 1000 Ancylostoma spp. L3 and distilled water in pots with 30 g of sand.ResultsEvidence of predatory activity was observed at the end of 15 days, where we observed the following percentages of reduction of L3: Group 1 (4.5%); Group 2 (24.5%); Group 3 (59.2%); Group 4 (58.8%); Group 5 (63%). However, difference was noted (p < 0.01) only at concentrations 15,000, 20,000 and 25,000 in relation to control group. In the assay B two groups were formed in Petri dishes of 9 cm in diameter containing agar water 2% medium. In the treated group, each Petri dish contained 500 Ancylostoma spp. L3 and 5 g of sand containing the isolate CG 768 at a concentration of 25,000 chlamydospores/g of sand, and the control group (without fungus) contained only 500 L3. At the end of 7 days the non-predation L3 of Petri dishes using the method of Baermann were recovered. Difference (p < 0.01) between groups on reducing the average number of Ancylostoma spp. L3 (percent reduction of 84%) was observed.ConclusionsThe results of this study confirm earlier work on the efficiency of the Duddingtonia genus in the control of Ancylostoma spp. infective larvae. 相似文献
10.
Katharina Stracke Poom Adisakwattana Suparat Phuanukoonnon Tippayarat Yoonuan Akkarin Poodeepiyasawat Paron Dekumyoy Kittipong Chaisiri Alexandra Roth Schulze Stephen Wilcox Harin Karunajeewa Rebecca J. Traub Aaron R. Jex 《PLoS neglected tropical diseases》2021,15(7)
Soil-transmitted helminths, such as roundworms (Ascaris lumbricoides), whipworms (Trichuris trichiura) and hookworms (Necator americanus and Ancylostoma spp.), are gastrointestinal parasites that occur predominantly in low- to middle-income countries worldwide and disproportionally impact children. Depending on the STH species, health status of the host and infection intensity, direct impacts of these parasites include malnutrition, anaemia, diarrhoea and physical and cognitive stunting. The indirect consequences of these infections are less well understood. Specifically, gastrointestinal infections may exert acute or chronic impacts on the natural gut microfauna, leading to increased risk of post-infectious gastrointestinal disorders, and reduced gut and overall health through immunomodulating mechanisms. To date a small number of preliminary studies have assessed the impact of helminths on the gut microbiome, but these studies are conflicting. Here, we assessed STH burden in 273 pre-school and school-aged children in Tha Song Yang district, Tak province, Thailand receiving annual oral mebendazole treatment. Ascaris lumbricoides (107/273) and Trichuris trichiura (100/273) were the most prevalent species and often occurred as co-infections (66/273). Ancylostoma ceylanicum was detected in a small number of children as well (n = 3). All of these infections were of low intensity (<4,999 or 999 eggs per gram for Ascaris and Trichuris respectively). Using this information, we characterised the baseline gut microbiome profile and investigated acute STH-induced alterations, comparing infected with uninfected children at the time of sampling. We found no difference between these groups in bacterial alpha-diversity, but did observe differences in beta-diversity and specific differentially abundant OTUs, including increased Akkermansia muciniphila and Bacteroides coprophilus, and reduced Bifidobacterium adolescentis, each of which have been previously implicated in STH-associated changes in the gut microfauna. 相似文献
11.
Keeseon S. Eom Tai-Soon Yong Woon-Mok Sohn Jong-Yil Chai Duk-Young Min Han-Jong Rim Hyeong-Kyu Jeon Virasack Banouvong Bounnaloth Insisiengmay Bounlay Phommasack 《The Korean journal of parasitology》2014,52(1):51-56
The prevalence of helminthic infections was surveyed on a total of 6,178 residents (males 2,549 and females 3,629) in 102 villages of 9 provinces in Lao PDR between 2007 and 2011 under the project of Korea-Laos Collaborative Project for Control of Foodborne Trematode Infections in Lao PDR. Fecal specimens were collected and examined by the Kato-Katz thick smear and Stoll''s egg counting techniques. The overall liver/intestinal helminth egg positive rate was 71.9% with a single or mixed infections with Opisthorchis viverrini and minute intestinal flukes (Ov/MIF), Ascaris lumbricoides, hookworms, Trichuris trichiura, Trichostrongylus sp., echinostomes, Taenia spp., and others. Ov/MIF revealed the highest prevalence (55.6%) followed by hookworms (27.8%) and T. trichiura (6.5%). The endemic regions with the highest prevalence of Ov/MIF were Savannakhet, Khammouane, Vientiane (Nam Ngum), Champasak (Khong Island), and Saravane Province. High prevalences of A. lumbricoides (33.8%), hookworms (47.8%), and T. trichiura (32.6%) were observed in Phongsaly, Luang Prabang, and Vientiane (Nam Ngum) areas, respectively. The results of this study highlight helminth parasites of current public health significance in different areas of Lao PDR. 相似文献
12.
Javier Sotillo Alejandro Sanchez-Flores Cinzia Cantacessi Yvonne Harcus Darren Pickering Tiffany Bouchery Mali Camberis Shiau-Choot Tang Paul Giacomin Jason Mulvenna Makedonka Mitreva Matthew Berriman Graham LeGros Rick M. Maizels Alex Loukas 《Molecular & cellular proteomics : MCP》2014,13(10):2736-2751
13.
Jong-Yil Chai Eun-Taek Han Eun-Hee Shin Woon-Mok Sohn Tai-Soon Yong Keeseon S. Eom Duk-Young Min Jin-Young Um Min-Sung Park Eui-Hyug Hoang Bounlay Phommasack Bounnaloth Insisiengmay Soon-Hyung Lee Han-Jong Rim 《The Korean journal of parasitology》2009,47(3):243-247
The prevalence of liver and intestinal helminth infections, including Opisthorchis, Haplorchis, Phaneropsolus, hookworms, Enterobius, and Taenia, was surveyed in Khammouane province, Lao PDR. Fecal specimens were collected from 1,242 people (590 men and 652 women) in 3 Mekong riverside villages and were examined by the Kato-Katz thick smear technique. The overall helminth egg positive rate was 81.1%. The positive rate for small trematode eggs, including Opisthorchis viverrini, heterophyids, and lecithodendriids, was 81.1% and the positive rate for hookworms was 6.7%. To obtain adult worms, 35 people who were positive for small trematode eggs were treated with 20-30 mg/kg praziquantel and 10-15 mg/kg pyrantel pamoate, and then purged. Diarrheic stools were collected from 33 of these people and searched for helminth parasites using a stereomicroscope. Mixed infections with various helminths (Haplorchis taichui, Haplorchis yokogawai, Prosthodendrium molenkampi, Phaneropsolus bonnei, echinostomes, hookworms, Trichostrongylus spp., Trichuris trichiura, Enterobius vermicularis, and/or Taenia saginata) were found. The total number of helminth specimens collected was 20,907 (approximately 634 per person). The most common species was H. taichui, followed by P. molenkampi, O. viverrini, P. bonnei, E. vermicularis, hookworms, and Trichostrongylus spp. These results show that diverse species of intestinal nematodes, trematodes, and cestodes are infecting humans in Khammouane province, Lao PDR. 相似文献
14.
The aim of present study was to compare the efficiency of a commercial assay and two conventional methods for fecal concentration in detecting canine gastrointestinal parasites. Fecal samples from 254 dogs were processed by centrifugation-sedimentation (CS), centrifugation-flotation (CF) and a commercial assay for fecal concentration (TF-test®). The following parasites were detected: Ancylostoma (37.8%), Giardia (16.9%), Toxocara canis (8.7%), Trichuris vulpis (7.1%), Isospora (3.5%), and Sarcocystis (2.7%). The calculated analytical sensitivity indicated that CF was more accurate (P < 0.01) in detecting Ancylostoma, T. canis, T. vulpis and Giardia infections. However, CF showed significantly higher sensitivity only for Ancylostoma, compared to the other two methods. The kappa index value of diagnostic agreement between TF-test and CF was high for T. canis (83%) and moderate for Giardia (72%) and Ancylostoma (63%). The advantages and limitations of each method were assessed for individual diagnosis and epidemiological investigation. 相似文献
15.
J.M. Smith 《International journal for parasitology》1976,6(1):9-13
Smith J. M. 1976. Comparative ultrastructure of the oesophageal glands of third stage larval hookworms. International Journal for Parasitology6: 9–13. The oesophageal glands of the third stage larvae of Necator americanus and Ancylostoma tubaeforme are compared, both before and after penetration through skin. The glands of “infective” larvae of N. americanus are densely packed with secretory granules, contrasting with a reduced gland size in the “penetrated” larvae coupled with the presence of gland secretions in the oesophageal lumen.No difference was observed between the glands of “infective” and “penetrated” larvae of A. tubaeforme. The role of oesophageal gland secretions for penetration of host skin is discussed. 相似文献
16.
17.
Entomopathogenic nematodes are used for biological control of insect pests. A method for improved cryopreservation of infective juvenile stage nematodes has been developed using Steinernema carpocapsae and Heterorhabditis bacteriophora. Optimum survival for both species was achieved with 12,000 infective juveniles/ml in glycerol and 7,500/ml in Ringer''s solution. For S. carpocapsae, maximum survival also was observed with 60,000 infective juveniles/ml in glycerol and 25,000/ml in Ringer''s solution. These concentrations resulted in 100% post-cryopreservation survival of S. carpocapsae and 100% retention of original virulence to Galleria mellonella larvae. This is the first report of achieving 100% survival of an entomopathogenic nematode after preservation in liquid nitrogen. Maximum survival of H. bacteriophora following cryopreservation was 87%. 相似文献
18.
Yan Hu Bin Zhan Brian Keegan Ying Y. Yiu Melanie M. Miller Kathryn Jones Raffi V. Aroian 《PLoS neglected tropical diseases》2012,6(11)
Background
Hookworm infections are one of the most important parasitic infections of humans worldwide, considered by some second only to malaria in associated disease burden. Single-dose mass drug administration for soil-transmitted helminths, including hookworms, relies primarily on albendazole, which has variable efficacy. New and better hookworm therapies are urgently needed. Bacillus thuringiensis crystal protein Cry5B has potential as a novel anthelmintic and has been extensively studied in the roundworm Caenorhabditis elegans. Here, we ask whether single-dose Cry5B can provide therapy against a hookworm infection and whether C. elegans mechanism-of-action studies are relevant to hookworms.Methodology/Principal Findings
To test whether the C. elegans invertebrate-specific glycolipid receptor for Cry5B is relevant in hookworms, we fed Ancylostoma ceylanicum hookworm adults Cry5B with and without galactose, an inhibitor of Cry5B-C. elegans glycolipid interactions. As with C. elegans, galactose inhibits Cry5B toxicity in A. ceylanicum. Furthermore, p38 mitogen-activated protein kinase (MAPK), which controls one of the most important Cry5B signal transduction responses in C. elegans, is functionally operational in hookworms. A. ceylanicum hookworms treated with Cry5B up-regulate p38 MAPK and knock down of p38 MAPK activity in hookworms results in hypersensitivity of A. ceylanicum adults to Cry5B attack. Single-dose Cry5B is able to reduce by >90% A. ceylanicum hookworm burdens from infected hamsters, in the process eliminating hookworm egg shedding in feces and protecting infected hamsters from blood loss. Anthelmintic activity is increased about 3-fold, eliminating >97% of the parasites with a single 3 mg dose (∼30 mg/kg), by incorporating a simple formulation to help prevent digestion in the acidic stomach of the host mammal.Conclusions/Significance
These studies advance the development of Cry5B protein as a potent, safe single-dose anthelmintic for hookworm therapy and make available the information of how Cry5B functions in C. elegans in order to study and improve Cry5B function against hookworms. 相似文献19.
Tai-Soon Yong Jong-Yil Chai Woon-Mok Sohn Keeseon S. Eom Hoo-Gn Jeoung Eui-Hyug Hoang Cheong-Ha Yoon Bong-Kwang Jung Soon-Hyung Lee Muth Sinuon Duong Socheat 《The Korean journal of parasitology》2014,52(6):661-666
In order to investigate the status of intestinal helminthic infections in Cambodia, epidemiological surveys were carried out on a national scale, including 19 provinces. A total of 32,201 fecal samples were collected from schoolchildren and adults between 2006 and 2011 and examined once by the Kato-Katz thick smear technique. The overall egg positive rate of intestinal helminths was 26.2%. The prevalence of hookworms was the highest (9.6%), followed by that of Opisthorchis viverrini/minute intestinal flukes (Ov/MIF) (5.7%), Ascaris lumbricoides (4.6%), and Trichuris trichiura (4.1%). Other types of parasites detected were Enterobius vermicularis (1.1%), Taenia spp. (0.4%), and Hymenolepis spp. (0.2%). The northwestern regions such as the Siem Reap, Oddar Meanchey, and Banteay Meanchey Provinces showed higher prevalences (17.4-22.3%) of hookworms than the other localities. The southwestern areas, including Koh Kong and Preah Sihanouk Provinces showed higher prevalences of A. lumbricoides (17.5-19.2%) and T. trichiura (6.1-21.0%). Meanwhile, the central and southern areas, in particular, Takeo and Kampong Cham Provinces, showed high prevalences of Ov/MIF (23.8-24.0%). The results indicate that a considerably high prevalence of intestinal helminths has been revealed in Cambodia, and thus sustained national parasite control projects are necessary to reduce morbidity due to parasitic infections in Cambodia. 相似文献
20.
Infections caused by Leishmania amazonensis are characterized by a persistent parasitemia due to the ability of the parasite to modulate the immune response of macrophages. It has been proposed that ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDases) could be able to suppress the host immune defense by reducing the ATP and ADP levels. The AMP generated from E-NTPDase activity can be subsequently hydrolyzed by ecto-nucleotidases, increasing the levels of adenosine, which can reduce the inflammatory response. In the present work, we provide new information about the role of E-NTPDases on infectivity and virulence of L. amazonensis. Our data demonstrate that not only the E-NTPDase activity is differentially regulated during the parasite development but also the expression of the genes ntpd1 and ntpd2. E-NTPDase activity increases significantly in axenic amastigotes and metacyclic promastigotes, both infective forms in mammalian host. A similar profile was found for mRNA levels of the ntpd1 and ntpd2 genes. Using parasites overexpressing the genes ntpd1 and ntpd2, we could demonstrate that L. amazonensis promastigotes overexpressing ntpd2 gene show a remarkable increase in their ability to interact with macrophages compared to controls. In addition, both ntpd1 and ntpd2-overexpressing parasites were more infective to macrophages than controls. The kinetics of lesion formation by transfected parasites were similar to controls until the second week. However, twenty days post-infection, mice infected with ntpd1 and ntpd2-overexpressing parasites presented significantly reduced lesions compared to controls. Interestingly, parasite load reached similar levels among the different experimental groups. Thus, our data show a non-linear relationship between higher E-NTPDase activity and lesion formation. Previous studies have correlated increased ecto-NTPDase activity with virulence and infectivity of Leishmania parasites. Based in our results, we are suggesting that the induced overexpression of E-NTPDases in L. amazonensis could increase extracellular adenosine levels, interfering with the balance of the immune response to promote the pathogen clearance and maintain the host protection. 相似文献