Apoptotic mechanisms are involved in the death of Strongyloides venezuelensis after triggering of nitric oxide.

Despite progress in understanding the role of nitric oxide (NO) in the pathogenesis of helminth infections, the role in strongyloidosis is unknown. Firstly, we studied the production of NO in mice infected with Strongyloides venezuelensis as well as in macrophage cultures stimulated with parasite antigens. Somatic larvae 3 (L3) and excretory-secretory female antigens stimulate specific NO production measured by Griess reaction and expression of inducible NO synthase by RT-PCR and quantitative PCR. Moreover, mice infected with S. venezuelensis produce NO in migration stages. Secondly, we analysed the effect of NO production on L3 and females of S. venezuelensis using NO donors such as diethylenetriamine and 3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene. Parasites died after NO donor treatment in a dose-dependent manner. Finally, apoptotic mechanisms are involved in the death of S. venezuelensis larvae.

Evaluation of the role of angiogenic factors in the pathogenesis of schistosomiasis.

Schistosomiasis is one disease produced by helminths, which affect many people in tropical areas. Granuloma formation is the main mechanism involved in the pathogenesis of this disease. Experimental studies have demonstrated angiogenesis (blood vessels formation from pre-existing vessels) in the initial phase of granuloma formation. In the present work, VEGF (vascular endothelial growth factor) levels were analyzed in sera from people diagnosed with different helminthic infections. Patients with schistosomiasis and filariasis had significantly high VEGF levels in compared with healthy people and patients diagnosed with hookworms. In addition, the effects of angiogenesis inhibition using anti-angiogenic factors (endostatin) were evaluated in a schistosomiasis murine model. A lesion decrease was observed in mice infected with Schistosoma mansoni and treated with endostatin. Finally, mechanisms of angiogenesis induction were studied and observed that cercariae antigens stimulated the angiogenic factors by host alveolar macrophages.

Role of angiogenic factors in acute experimental Strongyloides venezuelensis infection.

This study aims to investigate the role of angiogenic factors in the pathogenesis of experimental strongyloidiasis. Two complementary approaches were used: Firstly, CD1 mice were treated with endostatin, an angiogenesis inhibitor, and infected with Strongyloides venezuelensis. Also, the mechanisms involved in this process were studied. Parasitological examination revealed a significant decrease in egg per gram of faeces, number of collected larvae from lung tissue and number of collected adult females in mice treated with endostatin. Direct mechanisms with diminution of angiogenesis factors and an indirect mechanism with increase of eosinophil perhaps produced their effect. Secondly, the effect of the antigens responsible for stimulation of angiogenic factors [vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2)] from alveolar macrophages and the mechanisms involved in their production were investigated. Alveolar macrophage cells obtained by bronchoalveolar lavage were incubated at different concentrations of somatic and excretory/secretory antigens of S. venezuelensis. Also, mRNA levels of VEGF and FGF2 in macrophage cells were detected by RT-PCR. L3-PBS larvae antigens induced angiogenic factors. The relationship between angiogenesis factors and nitric oxide has been observed using nitric oxide synthase inhibitors.

Trichinella: differential expression of angiogenic factors in macrophages stimulated with antigens from encapsulated and non-encapsulated species.

The newborn larval stage of Trichinella spiralis enters the host striated skeletal muscle cell resulting in the formation of the nurse cell. Vascular Endothelial Growth Factor (VEGF) was detected in cells in the area immediately surrounding the nurse cells. However, no data are available on the antigens involved, the role of other angiogenic factors or the relationship of angiogenesis with Nitric Oxide (NO) production. Using macrophage cell culture we study the effect of different Trichinella L1 antigens from one encapsulated (T. spiralis) and one non-encapsulated (Trichinellapseudospiralis) on the expression of VEGF and basic Fibroblast Growth Factor (FGF2). Also, we investigate the relationship between the production of NO and angiogenic mediators. The results show that encapsulated and non-encapsulated Trichinella species are different in their capacity to stimulate the expression of VEGF and FGF2 from host macrophages. Finally, there is no relationship between angiogenic factors and NO production by T. spiralis antigen.

Progress in loop-mediated isothermal amplification assay for detection of Schistosoma mansoni DNA: towards a ready-to-use test.

Schistosomiasis is one of the most prevalent Neglected Tropical Disease, affecting approximately 250 million people worldwide. Schistosoma mansoni is the most important species causing human intestinal schistosomiasis. Despite significant efforts in recent decades, the global disease burden of schistosomiasis remains extremely high. This could partly be attributed to the absence of accurate diagnostic tools, primarily in endemic areas. Loop-mediated isothermal amplification (LAMP) is increasingly used in molecular diagnostics as a field-friendly alternative to many other complex molecular methods and it has been proposed as an ideal candidate for revolutionizing point-of-care molecular diagnostics. In a previous work, a LAMP-based method to detect S. mansoni DNA (SmMIT-LAMP) was developed by our research group for early diagnosis of active schistosomiasis in an experimental infection murine model. The SmMIT-LAMP has been further successfully evaluated in both human stool and snail samples and, recently, in human urine samples. In this study, we developed an important improvement for SmMIT-LAMP molecular assay, transforming it into a cold maintenance dry format suitable for potentially manufacturing as kit for ready-to-use for schistosomiasis diagnosis. This procedure could be applied to create dry LAMP kits for a laboratory setting and for diagnostic applications for other neglected tropical diseases.

The addition of a new immunomodulator with the adjuvant adaptation ADAD system using fatty acid binding proteins increases the protection against Fasciola hepatica.

Fatty acid binding proteins (FABP) have shown protective immune response against Fasciola hepatica infection. We evaluated the protection induced by the Fh12 FABP from F. hepatica (Fh12) combined with the new immunomodulator the lipidic aminoalcohol OA0012 in the ADAD system in mice and sheep. In this work we introduced a lipidic aminoalcohol OA0012 as immunomodulator alone or in combination with the hydroalcoholic extract of Phlebodium pseudoaureum; PAL. Mice vaccinated with ADAD containing OA0012+Fh12 or OA0012+Qs+Fh12 had survival rates of 40-50%. Sheep ADAD-vaccinated with OA0012+Qs+Fh12 showed lower fluke recovery, less hepatic lesions and higher post-infection daily weight gain than F. hepatica infected control animals. Sheep ADAD-vaccinated with OA0012 combined PAL and Qs+Fh12 showed lower fluke recovery (42%), lower adult worms count (57%) lower faecal egg count (38%), less hepatic lesions and higher post-infection daily weight gain than F. hepatica infected control animals. Thus, the addition of a new immunomodulator of synthesis to ADAD system with FABPs increased the protection against F. hepatica.

Progress in the development of Fasciola hepatica vaccine using recombinant fatty acid binding protein with the adjuvant adaptation system ADAD.

Fatty acid binding proteins (FABP) have been designed as a potential vaccine against fasciolosis. In this work, the immunoprophylaxis of the recombinant Fh15 FABP from F. hepatica (Fh15) in adjuvant/immunomodulator ADAD system was evaluated using mice and sheep challenged with F. hepatica. The ADAD system combines the Fh15 antigen with an immunomodulator (hydroalcoholic extract of Polypodium leucotomos; PAL) and/or an adjuvant (saponins of Quillaja saponaria; Qs) in a water/oil emulsion (30/70) with a non-mineral oil (Montanide). All the infected control mice died by 41-48 days post-infection. The mice vaccinated with ADAD only with PAL+Fh15 present a survival rate of 40-50% and those vaccinated with ADAD containing PAL+Qs+Fh15 had a survival rate of 50-62.5%. IgG1 antibodies were lower in surviving mice in comparison with non-surviving mice. The sheep vaccinated with ADAD PAL+Qs+Fh15 showed lower fluke recovery (43%), less hepatic lesions and higher post-infection daily weight gain than F. hepatica infected control animals. Thus, the ADAD system using recombinant fatty acid binding proteins from F. hepatica could be a good option to develop vaccines against F. hepatica.

Genetic and immunological characterization of the 14-3-3xi molecule from Schistosoma bovis.

Currently available candidate vaccines against schistosomiasis elicit only partial protection. In addition, the type of immune response that could lead to the highest level of protection against schistosomes has not yet been described. Thus, efforts should be made in both the identification of novel proteins essential for the parasite cycle and in the modulation of immune responses against these novel candidates through the combined use of immunomodulatory molecules. Several parasites have 14-3-3 proteins, and these proteins are known to play a key role in parasite biology. In the present work, we report the isolation and characterization of a new 14-3-3 gene from Schistosoma bovis and offer new information regarding the genetic structure of the gene. In addition, we have produced the corresponding recombinant protein. Finally, we describe the immune responses elicited by this protein when combined with 4 different immunomodulators in immunized mice.

Vaccination of mice and sheep with Fh12 FABP from Fasciola hepatica using the new adjuvant/immunomodulator system ADAD.

We evaluate the ability of a Fasciola hepatica FABP native antigen (Fh12) with a new vaccination system called ADAD to protect mice and sheep against an experimental F. hepatica infection. The vaccination protocol consists of a set of two injections. The first injection contains a micelle in which two components are included, saponin from Quillaja saponaria (Qs) and/or Anapsos (A) a Polypodium leucotomos hydroalcoholic extract, both emulsified in a non-mineral oil (Montanide) in a water/oil emulsion (30/70). This is subcutaneously injected to achieve the "adaptation" of the immune system to subsequent stimuli. The second injection contains in addition the Fh12 antigen. Two different experiments were carried out using two mouse strains (BALB/c and CD-1). Mice vaccinated with Qs+A+Fh12 presented a survival rate of 40%, when compared with control groups. Furthermore, we evaluated the efficiency of the vaccination in sheep against an experimental F. hepatica challenge. The vaccinated sheep presented lower fluke recovery (24.5%), number of eggs in bile fluid (58.1%) and faeces (40.3%) than control groups. The recovered flukes were shorter (32.7%), immature (34.0%) and with lower body mass (31.6%) than non-complete vaccinated sheep. Thus, the new ADAD system could be a good alternative for future vaccination experiments against fasciolosis.

The Schistosoma bovis Sb14-3-3zeta recombinant protein cross-protects against Schistosoma mansoni in BALB/c mice.

Current control programs against schistosomiasis could be reinforced through the use of an effective vaccine. Schistosome 14-3-3 proteins have been proposed as candidates for vaccine against the respective infections, and were seen to elicit high protection levels against Schistosoma bovis in a previous work done by our group. We have therefore investigated the protective capacity of the 14-3-3 protein from S. bovis - Sb14zeta - against Schistosoma mansoni in mice. In addition, we have addressed the influence of the co-administration of three different immunomodulators with the 14-3-3 polypeptide. Protection was high when the Sb14zeta protein was combined in two independent experiments with the AA2829 and PAL immunomodulatory molecules as regards both the reduction of worm numbers (mean: 64.8%) and egg loads in liver (mean: 73.9%) or intestine (mean: 71.5%). In contrast, the degree of protection achieved with the Sb14zeta-CpG vaccine was very low (14.9% reduction in worm numbers, and 46.6% and 32% reduction in liver and intestinal egg loads). The immune responses observed in the vaccinated animals showed that the production of IFNgamma and the absence of IL-4, accompanied by a strong humoral response, are insufficient to elicit protection against S. mansoni.

The Sb14-3-3zeta recombinant protein protects against Schistosoma bovis in BALB/c mice.

Schistosoma bovis is a trematode parasite mainly affecting cattle and sheep. Evidences about the arise of drug resistance and the high rates of re-infection of animals in endemic areas have pointed out the need of developing new control tools, e.g., effective vaccines. Schistosomes 14-3-3 proteins have been defined as vaccine candidates against respective infections. We have therefore investigated the protective capacity of the 14-3-3 protein from S. bovis - Sb14zeta - against S. bovis in mice. In addition, we have addressed the influence of the co-administration of four different immunomodulators with the 14-3-3 polypeptide. The values of protection against S. bovis were statistically significant when the Sb14zeta was combined in two independent experiments with the AA0029 (61.0% and 40.31%), AA2829 (49% and 36.3%) and PAL (49% and 40.075%) immunomodulatory molecules. Immune responses from vaccinated animals showed that the highest protection rates do not necessarily match with a dominant Th1-type response.

A new PCR-based approach for the specific amplification of DNA from different Schistosoma species applicable to human urine samples.

Currently available methods for the diagnosis of human schistosomiasis often lack enough sensitivity and specificity. Recently, several authors have developed more specific and sensitive diagnostic methods, mainly based on the polymerase chain reaction (PCR) technique. Nevertheless, these have been only applied for the diagnosis of 1 out of 4 Schistosoma species affecting man (S. mansoni). Additionally, application of specific PCR has been exclusively used for blood or faecal patients' samples. Here, we develop a new, high sensitive PCR approach that allows the genus- and species-specific amplification of the main 4 Schistosoma species causing disease in man plus S. bovis. We further successfully apply this technique for the detection of parasite DNA in easy-to-handle urine samples from patients with schistosomiasis. With these samples, we have found 94.4% sensitivity and 99.9% specificity when applying a genus-specific (Schistosoma spp.) primer pair, and 100% sensitivity and 98.9% specificity in a species-specific (S. mansoni) PCR.