New insights into the life cycle of Platynosomum (Trematoda: Dicrocoeliidae).

The platynosomiasis, a worldwide parasitic disease with importance for domestic cat, has an etiological agent species of trematodes of the genus Platynosomum, whose complete life cycles are not yet known. The real role of lizards in the transmission of this dicrocoeliid parasite (as obligatory intermediate or paratenic host) still needs to be defined. In the present study, oval-shaped encysted metacercariae obtained from terrestrial isopods (Oniscidea sp. and Nagurus nanus) and elongated excysted metacercariae found in biliary ducts and gallbladder of lizards (Hemidactylus mabouia) in Brazil were used for morphological characterization and experimental infection of mice. Adult parasites recovered from bile ducts and liver of mice inoculated orally with metacercariae from both hosts (isopods and lizards) were identified as Platynosomum illiciens (=Platynosomum fastosum), showing that lizards are paratenic (not obligatory) hosts involved in the life cycle of this parasite. Moreover, Subulina octona is reported as the first intermediate host of P. illiciens in South America, and terrestrial isopods are presented here as new natural second intermediate hosts of the parasite. Finally, it is pointed out that high prevalence and intensity of infection of intermediate and paratenic hosts were observed. These findings on the life cycle of P. illiciens are relevant considering that they may indicate possible control measures of platynosomiasis.

Peptides containing T cell epitopes, derived from Sm14, but not from paramyosin, induce a Th1 type of immune response, reduction in liver pathology and partial protection against Schistosoma mansoni infection in mice.

Sm14 and paramyosin are two major Schistosoma mansoni vaccine candidate antigens. Recently, we have identified Sm14 and paramyosin epitopes that are recognized by T cells of resistant individuals living in endemic areas for schistosomiasis. Herein, mice were immunized with these peptides separately or in association in order to evaluate their vaccine potential. Immunization of mice with Sm14 peptides alone or mixed with paramyosin peptides was able to induce 26%-36.7% or 28%-29.2% of worm burden reduction, 67% or 46% of intestinal eggs reduction and also 54%-61% or 43%-52% of liver pathology reduction, respectively. Protection was associated with a Th1 type of immune response induced by Sm14 peptide immunization. In contrast, paramyosin peptide vaccination did not engender protective immunity or liver pathology reduction and immunization was associated with a Th2 type of immune response.

Oral immunization with Salmonella harboring a Sm14-based DNA vaccine does not protect mice against Schistosoma mansoni infection.

The protection against Schistosoma mansoni infection was evaluated in SWISS mice orally vaccinated with an attenuated strain of Salmonella carrying a Sm14-based DNA vaccine. Although this formulation was not able to afford a reduction in the worm burden, a non-antigen-specific decrease in schistosome-induced granulomatous reaction was verified in livers of mice that received Salmonella.

Enhanced oral delivery of antimony from meglumine antimoniate/beta-cyclodextrin nanoassemblies.

The composition comprising the highly water-soluble drug meglumine antimoniate (MA) and beta-cyclodextrin (beta-CD) was shown previously to enhance the absorption of Sb by oral route and render MA orally active in a murine model of cutaneous leishmaniasis. This unexpected behaviour was attributed, in part, to the fact that the heating of equimolar mixture of MA and beta-CD (first step of preparation of MA/beta-CD composition) induced the depolymerization of MA from high-molecular weight Sb complexes into 1:1 Sb-meglumine complex, resulting in an enhanced oral bioavailability of Sb. In the present work, we demonstrate that the heated MA+beta-CD mixture still produced significantly lower serum Sb levels when compared to the MA/beta-CD composition, indicating that the freeze-drying process (second step of preparation of MA/beta-CD composition) is required for achieving a high absorption of Sb by oral route. To get insight into the physicochemical alterations induced by the freeze-drying step, the MA/beta-CD composition was further characterized by circular dichroism, (1)H NMR and ESI(-)-MS and photon correlation spectroscopy. The freeze-drying process was found to promote the formation of supramolecular nanoassemblies with a mean hydrodynamic diameter of 190 nm, comprising 1:2:1, 2:2:1 and 2:2:2 NMG-Sb-beta-CD complexes. Another important observation was the ability of the MA/beta-CD composition to act as a sustained release system of the antimonial drug MA, suggesting that this property may result in the change of the drug absorption site in the gastrointestinal tract. A model is proposed for the mechanisms involved in the enhanced absorption of Sb from the MA/beta-CD composition.

Granulomatous nephritis in psittacines associated with parasitism by the trematode Paratanaisia spp.

Trematodes belonging to the family Eucotylidae are parasites of the kidney and ureter, and affect several bird species. However, psittacines have not been identified as hosts of these parasites. Three birds, an adult female blue and gold macaw (Ara ararauna), an adult female blue-winged macaw (Propyrrhura maracana) and an adult male white-eared parakeet (Pyrrhura leucotis) were admitted at the Veterinary Hospital of the Fundação Zoo-Botânica de Belo Horizonte, Brazil (FZB/BH). All three birds had severe dehydration and cachexia. The blue and gold macaw presented with dyspnea, apathy, and incoordination. Blood cell counts indicated discrete anemia and leucopenia. Blood biochemistry revealed significant increase in levels of uric acid (61 mg/dl) and blood urea nitrogen (22 mg/dl). The bird died within 24 h after admission. The other two birds were admitted with similar clinical signs, but died prior to a complete clinical examination. At the necropsy, in all the three birds, the kidneys were enlarged with brown-yellowish discoloration and irregular cortical surface. On the cut surface, there was a brown-yellowish material with few visible parasites flowing out of the parenchyma. When fragments of the kidneys were placed in 10% formalin, a large number of trematodes came out of the renal parenchyma. The parasites were identified as Paratanaisia robusta infecting all three birds, and P. bragai infecting the blue-winged macaw and the white-eared parakeet. Histologically, there was an interstitial, multifocal to coalescent, lymphoplasmacytic infiltrate with some epithelioid macrophages, and a few heterophils, characterizing a granulomatous nephritis. Adult worms and eggs were observed within dilated tubules and in the renal pelvis. In the blue and gold macaw, some parasite eggs were located interstitially associated with an intense adjacent granulomatous reaction.

Putative new genera and species of avian schistosomes potentially involved in human cercarial dermatitis in the Americas, Europe and Africa.

New larval avian schistosomes found in planorbid snails from Brazil and USA were used for morphological and molecular studies. Eggs with a distinctive long polar filament were found in ducks infected experimentally with Brazilian cercariae. Similar eggs were reported previously in wild or experimentally infected anatids from Brazil, South Africa, and the Czech Republic. Molecular phylogenetic analyses showed that the North American and European schistosomes are sister taxa, which are both sister to the Brazilian species. However, these clades do not group with any named genus. Molecular data plus egg morphology suggest that these are new putative genera and species of avian schistosomes that can cause human cercarial dermatitis in the Americas, Africa and Europe.

Oral administration of a live Aro attenuated Salmonella vaccine strain expressing 14-kDa Schistosoma mansoni fatty acid-binding protein induced partial protection against experimental schistosomiasis.

We report the oral vaccination of SWISS mice with an Aro attenuated Salmonella enterica var. Typhimurium vaccine strain expressing the 14-kDa Schistosoma mansoni antigen, Sm14. Bacterial adjuvants, including (i) Lactococcus lactis expressing interleukin-12 (IL-12) and (ii) Lactobacillus delbrueckii UFV-H2b20, were also employed in oral immunization assays. Detection assays to specific IgG and IgA anti-Sm14 antibodies were performed to evaluate humoral immune responses in vaccinated mice. An increase in specific IgG titers was observed; however, no IgA production was detected. The protection levels against schistosomiasis (34.9-49.5%) obtained with all experimental formulations in this work were very similar to values reported by previous studies, which used purified recombinant Sm14 for parenteral vaccination of mice. There was a slight reduction in hepatic granulomas of mice vaccinated with Salmonella. Oogram studies showed diminished numbers of S. mansoni eggs in the intestinal wall of vaccinated mice, but individual female worm fecundity did not seem to be affected by our immunization protocol.

The Apple Snail Pomacea maculata (Caenogastropoda: Ampullariidae) as the intermediate host of Stomylotrema gratiosus (Trematoda: Stomylotrematidae) in Brazil: the first report of a mollusc host of a Stomylotrematid Trematode.

Trematodes belonging to the family Stomylotrematidae are intestinal parasites of birds. Despite the worldwide distribution and diversity of host species, the first intermediate host remains unknown. For a survey of parasites of Pomacea maculata , snails were collected from the municipality of São Vicente Férrer, state of Maranhão, northeastern Brazil. In the present study, the xiphidiocercariae shed from these snails were used in the experimental infection of the water bug Belostoma plebejum. The insect mortality was observed 30 days post-infection, and the metacercariae recovered in the body cavity of B. plebejum were identified as Stomylotrema gratiosus. This is the first report of an ampullariid snail as intermediate host of stomylotrematid trematodes.

Enhanced schistosomicidal efficacy of tartar emetic encapsulated in pegylated liposomes.

The aim of the present study was to evaluate the ability of liposomes to improve the efficacy of tartar emetic (TA) against established Schistosoma mansoni infection. TA was used as a schistosomicidal drug model and both conventional liposomes (CL) and long-circulating pegylated liposomes (LCL) were evaluated. In the first experiment, TA, either free or encapsulated within CL or LCL, was given intraperitoneally (i.p.) as a single dose of 11 mg Sb/kg to mice experimentally infected with S. mansoni. Only the group treated with LCL showed a significant (55%) reduction in the worm burden, compared to the control groups (untreated or treated with empty LCL). In the second experiment, the efficacy of TA-containing LCL was evaluated at a higher dose (27 mg Sb/kg) by both subcutaneous (s.c.) and i.p. routes. Reduction levels of 67 and 82% were achieved by s.c. and i.p. routes, respectively. Strikingly, all mice survived to this high dose of antimony. This is in contrast with free TA that was lethal in 100% of mice at the same dose. The present work demonstrates that LCL reduce the acute toxicity of TA and effectively deliver this drug to S. mansoni during the late stages of parasite infection.

Physa marmorata (Mollusca: Physidae) as a natural intermediate host of Trichobilharzia (Trematoda: Schistosomatidae), a potential causative agent of avian cercarial dermatitis in Brazil.

Species of Trichobilharzia are the main etiological agents of cercarial dermatitis in humans, which is considered a re-emerging disease. Despite the diversity and global distribution of species of this genus, studies of Trichobilharzia are scarce in South America. The goal of our investigations is better understand the diversity, distribution and life cycle of avian schistosomes and their likely role in causing dermatitis in Brazil. As part of this effort, cercariae found in naturally infected Physa marmorata were identified by morphological and molecular (mitochondrial cox1, nuclear ITS1 and 28S gene regions) methods as Trichobilharzia sp. These cercariae are similar morphologically to T. jequitibaensis described previously from Brazil and similar genetically to the North American physid transmitted species T. querquedulae and T. physellae. This is the first report of a potential agent of cercarial dermatitis from naturally infected snails from Brazil and first molecular characterization of a South American species of Trichobilharzia. A discussion follows concerning the potential role of this species has in outbreaks of dermatitis in Brazil.

Schistosoma mansoni tegument protein Sm29 is able to induce a Th1-type of immune response and protection against parasite infection.

BACKGROUND: Schistosomiasis continues to be a significant public health problem. This disease affects 200 million people worldwide and almost 800 million people are at risk of acquiring the infection. Although vaccine development against this disease has experienced more failures than successes, encouraging results have recently been obtained using membrane-spanning protein antigens from the tegument of Schistosoma mansoni. Our group recently identified Sm29, another antigen that is present at the adult worm tegument surface. In this study, we investigated murine cellular immune responses to recombinant (r) Sm29 and tested this protein as a vaccine candidate. METHODS AND FINDINGS: We first show that Sm29 is located on the surface of adult worms and lung-stage schistosomula through confocal microscopy. Next, immunization of mice with rSm29 engendered 51%, 60% and 50% reduction in adult worm burdens, in intestinal eggs and in liver granuloma counts, respectively (p<0.05). Protective immunity in mice was associated with high titers of specific anti-Sm29 IgG1 and IgG2a and elevated production of IFN-gamma, TNF-alpha and IL-12, a typical Th1 response. Gene expression analysis of worms recovered from rSm29 vaccinated mice relative to worms from control mice revealed a significant (q<0.01) down-regulation of 495 genes and up-regulation of only 22 genes. Among down-regulated genes, many of them encode surface antigens and proteins associated with immune signals, suggesting that under immune attack schistosomes reduce the expression of critical surface proteins. CONCLUSION: This study demonstrates that Sm29 surface protein is a new vaccine candidate against schistosomiasis and suggests that Sm29 vaccination associated with other protective critical surface antigens is the next logical strategy for improving protection.

[Keys to families and genera of gerromorpha and nepomorpha (Insecta: Heteroptera) in the central Amazonia, Brazil]. / Chaves de identificação para famílias e gêneros de gerromorpha e nepomorpha (Insecta: Heteroptera) na Amazônia central.

Few studies have been done in Brazil on aquatic and semi-aquatic Gerromorpha and Nepomorpha (Heteroptera), Minas Gerais being the state where these insects have been studied the most. The present study presents keys for identification of Gerromorpha and Nepomorpha adults, thus providing a tool for ecological studies on aquatic insects in Central Amazonia. The specimens used to elaborate the taxonomic keys were collected in Presidente Figueiredo county in streams and artificial lakes and in Manaus county in streams, white-water floodplain (várzea) lakes and Rio Negro black-water flooded forest (igapó). Specimens from the invertebrate collection of the Instituto Nacional de Pesquisas da Amazonia (INPA) were also examined and included in the keys. Thirty one genera from 13 families of the infra-orders mentioned.

[Aquatic heteroptera from Mariana County, Minas Gerais, Brazil]. / Heterópteros aquáticos oriundos do município de Mariana, MG.

In surveys carried out in lotic and lentic environments in Mariana County, Minas Gerais state, Brazil, 35 genera and 64 species of aquatic and semi-aquatic Heteroptera were recorded, distributed in 13 families. Thirty four species were collected in lentic environments, while in lotic environments 48 species were collected, some of them common to both environments. Nepomorpha presented the greatest number of species (45), markedly for the family Naucoridae, represented by 12 species. Among the 19 Gerromorpha species collected, eight were Veliidae and six were Gerridae.

Oral delivery of meglumine antimoniate-beta-cyclodextrin complex for treatment of leishmaniasis.

The need for daily parenteral administration represents one of the most serious limitations in the clinical use of pentavalent antimonials against leishmaniasis. In this work, we investigated the ability of beta-cyclodextrin to enhance the oral absorption of antimony and to promote the oral efficacy of meglumine antimoniate against experimental cutaneous leishmaniasis. The occurrence of interactions between beta-cyclodextrin and meglumine antimoniate was demonstrated through the changes induced in the spin lattice relaxation times of protons in both compounds. When free and complexed meglumine antimoniate were given orally to Swiss mice, plasma antimony levels were found to be about three times higher for the meglumine antimoniate-beta-cyclodextrin complex than for the free drug. Antileishmanial efficacy was evaluated in BALB/c mice experimentally infected with Leishmania amazonensis. Animals treated daily with the complex (32 mg of Sb/kg of body weight) by the oral route developed significantly smaller lesions than those treated with meglumine antimoniate (120 mg of Sb/kg) and control animals (treated with saline). The effectiveness of the complex given orally was equivalent to that of meglumine antimoniate given intraperitoneally at a twofold-higher antimony dose. The antileishmanial efficacy of the complex was confirmed by the significantly lower parasite load in the lesions of treated animals than in saline-treated controls. This work reports for the first time the effectiveness of an oral formulation for pentavalent antimonials.