An open label, randomized clinical trial to compare the tolerability and efficacy of ivermectin plus diethylcarbamazine and albendazole vs. diethylcarbamazine plus albendazole for treatment of brugian filariasis in Indonesia.

Improved treatments for lymphatic filariasis (LF) could accelerate the global elimination program for this disease. A triple drug combination of the anti-filarial drugs ivermectin, diethylcarbamazine (DEC) and albendazole (IDA) has been shown to be safe and effective for achieving sustained clearance of microfilariae (Mf) of the filarial parasite Wuchereria bancrofti from human blood. However, the triple drug combination has not been previously been evaluated for treatment of brugian filariasis, which accounts for about 10% of the global LF burden. This hospital-based clinical trial compared the safety and efficacy of IDA with that of the standard treatment (DEC plus albendazole, DA) in persons with Brugia timori infections on Sumba island, Indonesia. Fifty-five asymptomatic persons with B. timori Mf were treated with either a single oral dose of IDA (28 subjects) or with DEC plus albendazole (DA, 27 subjects). Participants were actively monitored for adverse events (AE) for two days after treatment by nurses and physicians who were masked regarding treatment assignments. Passive monitoring was performed by clinical teams that visited participant's home villages for an additional five days. Microfilaremia was assessed by membrane filtration of 1 ml night blood at baseline, at 24h and one year after treatment. IDA was more effective than DA for completely clearing Mf at 24 hours (25/28, 89% vs. 8/27, 30%, P < 0.001). By 12 months after treatment, only one of 27 IDA recipients had Mf in their blood (4%) vs. 10 of 25 (40%) in persons treated with DA (P = 0.002). Approximately 90% of participants had antibodies to recombinant filarial antigen BmR1 at baseline. Antibody prevalence decreased to approximately 30% in both treatment groups at 12 months. About 45% of persons in both treatment groups experienced AE such as fever, muscle aches, lower back, joint and abdominal pain. These were mostly mild and most common during the first two days after treatment. No participant experienced a severe or serious AE. This study showed that IDA was well-tolerated and significantly more effective for clearing B. timori Mf from the blood than DA. Larger studies should be performed to further assess the safety and efficacy of IDA as a mass drug administration regimen to eliminate brugian filariasis. Trial Registration: NCT02899936.

Identification and characterization of epitopes on Plasmodium knowlesi merozoite surface protein-142 (MSP-142) using synthetic peptide library and phage display library.

Plasmodium knowlesi can cause potentially life threatening human malaria. The Plasmodium merozoite surface protein-142 (MSP-142) is a potential target for malaria blood stage vaccine, and for diagnosis of malaria. Two epitope mapping techniques were used to identify the potential epitopes within P. knowlesi MSP-142. Nine and 14 potential epitopes were identified using overlapping synthetic peptide library and phage display library, respectively. Two regions on P. knowlesi MSP-142 (amino acid residues 37-95 and residues 240-289) were identified to be the potential dominant epitope regions. Two of the prominent epitopes, P10 (TAKDGMEYYNKMGELYKQ) and P31 (RCLLGFKEVGGKCVPASI), were evaluated using mouse model. P10- and P31-immunized mouse sera reacted with recombinant P. knowlesi MSP-142, with the IgG isotype distribution of IgG2b>IgG1>IgG2a>IgG3. Significant higher level of cytokines interferon-gamma and interleukin-2 was detected in P31-immunized mice. Both P10 and P31 could be the suitable epitope candidates to be used in malaria vaccine designs and immunodiagnostic assays, provided further evaluation is needed to validate the potential uses of these epitopes.

A protocol for HPLC-based activity profiling for natural products with activities against tropical parasites.

HPLC based activity profiling is an effective strategy to accelerate the discovery of new hits and leads from nature. It conveniently combines the superior separation power of HPLC micro scale compound separation with miniaturized biological screening methods, and on-line and off-line spectroscopy (PDA, MS(n), HR-MS, NMR) for structure elucidation. We here describe a protocol for the discovery of natural products with antimalarial, antileishmanial and antitrypanosomal activity, from extracts libraries in 96-well format. Analytical gradient HPLC on a 3 x 150 mm column of 350 microg of extract, and collection of one-minute fractions into 96 deep-well microtiter plates, parallel evaporation of the micro-fractions, and a suitable dilution scheme permitted parallel activity profiling against three parasites from a single HPLC injection. The protocol was validated with extracts and positive controls such as Artemisia annua.

Human placental extract offers protection against experimental visceral leishmaniasis: a pilot study for a phase-I clinical trial.

An aqueous extract of human placenta (HPE) was found to offer protection against established experimental visceral leishmaniasis in BALB/c mice and hamsters, whether the Leishmania donovani strain involved was one that was sensitive or resistant to pentavalent antimony. Intraperitoneal administration of the extract, into mice or hamsters that had been infected 2 months previously, led to antileishmanial T-cell proliferation among splenic mononuclear cells, the generation of host-protective cytokines (interferon-gamma, tumour necrosis factor and interleukin-12) and the upregulation of the expression of inducible nitric oxide synthase (and subsequent NO generation) in splenocytes. Furthermore, splenic macrophages from the HPE-treated mice showed increased generation of reactive oxygen species and enhanced surface expression of antigens of major histocompatibility complex class II (MHCII), and the extract restored the otherwise-defective antigen-presenting ability of the macrophages. Thus, in mice and hamsters infected with L. donovani, HPE therapy can stimulate both arms of the host's immune system and favour the complete resolution of the leishmanial infection. Among five human cases of visceral leishmaniasis, 30 daily intramuscular injections of HPE, at doses much lower than those used in the experimental infections, also gave very promising results. Based on the results of this pilot study, a further evaluation of the efficacy of HPE therapy, which may offer a cost-effective way of improving the treatment of antimony-resistant cases of visceral leishmaniasis, is being undertaken.

Alpha 2 macroglobulin activity in rats infected with Typanosoma lewisi and treated with cyclophosphamide and its effect on the malignancy of the disease.

BACKGROUND & OBJECTIVES: Trypanosoma lewisi is a common, flagellated parasite of the rat. Our previous study showed that rabbits injected with serum collected from rats infected with Trypanosoma lewisi and treated with cyclophosphamide (CyI) produced high levels of antibodies against a new protein in the CyI rat serum. RESULTS: In the present study, this protein was characterised as alpha2 macroglobulin (alpha2M) and the kinetics of its production and its influence on the malignancy of the disease were determined. In rats infected with T. lewisi, alpha2M was first demonstrated and peaked on the second day post-infection (972 microg/ml) and then reduced gradually, reaching a level of 32 microg/ml on the eighth day post-infection. However, in the CyI rats the level of alpha2M was gradually increased as the disease progressed, reaching a level of 890 microg/ml on the eighth day post-infection. Injection of both crude and purified alpha2M into rats infected with T. lewisi led to increased parasitaemia. INTERPRETATION & CONCLUSION: The present study suggests that increased levels of alpha2M in the CyI rats contribute to the malignancy of the disease.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) reduces Leishmania major burdens in C57BL/6 mice.

Acute exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can suppress adaptive immunity. In this study, pre-exposure of Leishmania major-infected mice to TCDD caused a dose-dependent and unexpected decrease in parasite burdens on day 20 after infection. In contrast, TCDD-mediated lymphoid atrophy, suppressed antibody levels, and enhanced interleukin-2 production were observed as expected. These results suggest that TCDD may enhance resistance to L. major in the face of immune suppression.

Trypanosoma cruzi-infected individuals demonstrate varied antibody responses to a panel of trans-sialidase proteins encoded by SA85-1 genes.

Chronic infection with Trypanosoma cruzi causes significant morbidity and mortality. The parasite expresses on its surface and sheds into the extracellular milieu a large superfamily of trans-sialidase proteins. Previous studies have demonstrated that during T. cruzi infection, the trans-sialidase superfamily stimulates an antibody response, but how individuals respond to different proteins of the trans-sialidase superfamily remain poorly defined. In this report, we present an analysis of the antibody response of chronically infected individuals and inbred strains of mice to a panel of 11 different trans-sialidase proteins encoded by surface antigen 85 kD (SA85-1) genes. These data indicate that: (1) 90% of the individuals tested generated antibodies to one or more trans-sialidase proteins; (2) the individuals develop different patterns of antibody responsiveness to the panel of trans-sialidase proteins; (3) three inbred strains of mice develop trans-sialidase antibody responses, but each strain develops a different pattern of antibody response to the panel of trans-sialidase proteins; (4) the differences in the pattern of antibody response by the mouse strains are independent of MHC differences; and (5) trans-sialidase proteins that do not stimulate an antibody response during T. cruzi infection can stimulate a response following immunization. Together these data indicate that during T. cruzi infection individuals develop a diverse trans-sialidase antibody response that appears to be affected by genetic and environmental factors.

The binding and distribution of albendazole and its principal metabolites in Giardia duodenalis.

Trophozoites of the protozoan parasite Giardia duodenalis were exposed to various albendazole concentrations for 4 h, washed, fixed and incubated with antibodies raised against albendazole and its two major metabolites albendazole sulphoxide and albendazole sulphone. Tubulin antibodies were also used. A peroxidase- or FITC-conjugated secondary antibody was used to detect the primary antibody with transmission electron microscopy or confocal laser scanning microscopy, respectively. Albendazole, a benzimidazole compound, was detected in the mid-dorsal region of trophozoites, albendazole sulphoxide in the posterior-dorsal region and albendazole sulphone in clusters above the median bodies. Tubulin was recognised in the ventral disk. This is the first indication that G. duodenalis may be capable of metabolising albendazole and the potential path of the metabolised drug traced within the trophozoite. Fluorescence measurements revealed that albendazole sulphoxide binding decreased and albendazole sulphone binding increased with exposure of the trophozoites to increasing albendazole concentration. This indicates that if albendazole was being metabolised by trophozoites, it occurred to a greater extent following exposure to higher albendazole concentrations.

Haemolytic activities of plant saponins and adjuvants. Effect of Periandra mediterranea saponin on the humoral response to the FML antigen of Leishmania donovani.

An 87.7% (P < 0.01) and 84% (P < 0.001) of protection against visceral leishmaniasis was achieved in CB hamsters and Balb/c mice, respectively, with saponin combined to the fucose-mannose ligand of Leishmania donovani (FML). However, an undesirable haemolytic effect was described for several saponins. Aiming to improve the formulation with FML/saponin, we comparatively analysed the haemolytic potential of recently characterized plant saponins and currently used adjuvants. The haemolytic activity of steroidic saponins from Agave sisalana; Smilax officinalis as well as commercial saponin (Riedel De Haën's), was higher than that of triterpenoid ones (Bredemeyera floribunda; Periandra mediterranea) and the Freund's complete adjuvant. The concentration resulting in 50% haemolysis was 500 micrograms ml-1 for aluminum hydroxide. The low haemolytic effect of P. mediterranea saponin was abolished by removal of its glycidic moiety and its sapogenin fraction as well as the Freund's Incomplete Adjuvant were non-haemolytic within this range. Furthermore, the adjuvant effect of three doses of P. mediterranea saponin injected with the FML antigen of L. donovani, was assayed in mice, either by the intraperitoneal (i.p.) or the subcutaneous (s.c.) route. The anti-FML IgG antibody levels increased and detectable levels were observed up to 3 months in the s.c. group. The response was expanded in both groups after an injection with a fourth vaccine dose. The IgG response showed increased levels of IgG2a only in the i.p. group, while IgG2b and IgG1 but not IgG3 antibodies were higher than controls in both groups. In conclusion, the results suggest that the recently described triterpenoid fractions of P. mediterranea can be safely used as adjuvant with low or non-haemolytic effect.

Lipopeptide immunization without adjuvant induces potent and long-lasting B, T helper, and cytotoxic T lymphocyte responses against a malaria liver stage antigen in mice and chimpanzees.

We have employed a 26-amino-acid synthetic peptide based on Plasmodium falciparum liver stage antigen-3 to evaluate improvements in immunogenicity mediated by the inclusion of a simple lipid-conjugated amino acid during peptide synthesis. Comparative immunization by the peptide in Freund's adjuvant or by the lipopeptide in saline shows that the addition of a palmitoyl chain can dramatically increase T helper (Th) cell responses in a wide range of major histocompatibility complex (MHC) class II haplotypes, to the extent that responses were induced in mice otherwise unable to respond to the non-modified peptide injected with Freund's adjuvant, and that the increased immunogenicity of the lipopeptide led to high and longer lasting antibody production (studied up to 8 months). B and T cell responses induced by the lipopeptide were reactive with native parasite protein epitopes, and a lipopeptide longer than ten amino acids was endogenously processed to associate with MHC class I and elicit cytotoxic T lymphocyte (CTL) responses. Finally, the lipopeptide was safe and highly immunogenic in chimpanzees, whose immune system is very similar to that of humans. Our results suggest that relatively large synthetic peptides, carefully chosen from pertinent areas of proteins and incorporating a simple palmitoyl-lysine, can induce not only CTL, but also strong Th and antibody responses in genetically diverse populations. Lipopeptides engineered in this way are simple to produce and purify under GMP conditions, they are well tolerated by apes, and with the enhanced immunogenicity without the need for adjuvant that we report here, they offer a quick and relatively low-cost route to provide material for human malaria vaccination trials.

Activity of antibodies against Salmonella dublin, Toxoplasma gondii, or Actinobacillus pleuropneumoniae in sera after treatment with electron beam irradiation or binary ethylenimine.

Viral contamination of biological material may constitute a risk when samples are exchanged between countries, and it may be necessary to subject the material to an inactivation treatment. The present study investigated possible adverse effects on antibody activity subsequent to either electron beam irradiation or binary ethylenimine (BEI) treatment. The treatments were performed with sera obtained from pigs or cattle. For each treatment level, the posttreatment activity was plotted against the pretreatment activity, and regression analyses were carried out. The slope of the regression line was used as an estimate for the relative posttreatment activity. For a Toxoplasma gondii indirect enzyme-linked immunosorbent assay (ELISA) and agglutination assay as well as for a Salmonella dublin indirect ELISA, the posttreatment activity was more than 89% of the pretreatment activity when the samples were irradiated in the frozen state (on dry ice) with up to 46. kGy or when they were treated with 5 or 10 mM BEI for up to 48 h. The samples were more sensitive to irradiation in the liquid state. Thus, samples irradiated with 22.6 kGy retained 98% of their activity in the indirect ELISA when they were irradiated in the frozen state on dry ice but only 35% of their activity when they were irradiated in the liquid state at 0 degrees C. The patterns seen in an S. dublin blocking ELISA and an Actinobacillus pleuropneumoniae complement fixation assay differed in that samples with a low level of pretreatment activity were subject to a relatively greater decrease in activity than samples with a high level of pretreatment activity. The complement fixation assay was particularly sensitive to irradiation of serum. It is concluded that serum samples retain sufficient activity by both methods of virus inactivation, especially when used in indirect ELISA or in the T. gondii agglutination assay.

Chemoprophylaxis of Cryptosporidium parvum infection with paromomycin in kids and immunological study.

The anticryptosporidial activity of paromomycin, a natural antibiotic weakly absorbed when administered per os, was assessed in goat kids experimentally infected once via the oral route with 10(6) Cryptosporidium parvum oocysts. Paromomycin used prophylactically at a dose of 100 mg/kg of body weight per day from day-1 to day 10 (day 0 was the inoculation day) prevented infection during the period of drug administration. A delayed low infection was suggested by an antibody rise, but the infection developed below the microscopic detection limits. This low parasite development induced a partial immunity in kids, which reacted immunologically to a challenge on day 21 without symptoms or detectable oocyst shedding. So, paromomycin is a good candidate for field trials because it is prophylactically effective against experimental C. parvum infection and well tolerated by animals. This drug would be useful in an adapted form as an anticryptosporidial agent for neonatal ruminants.

Construction of synthetic immunogens: use of T- and B-cell epitopes of CS and RESA proteins of Plasmodium falciparum.

An invariant T-helper epitope of the sequence ENDIEKKICKMEKCSSVFNV (residue no. 376-395) from the circumsporozoite (CS) protein was coupled chemically with the repeat sequences, namely (EENV)2, EENVEHDA and DDEHVEEPTVA, of ring-infected erythrocyte surface antigen (RESA) protein of Plasmodium falciparum. The CS sequence was tested for helper and proliferative activity in five inbred strains of mice of different haplotypes. The CS peptide showed dose-dependent lymphocyte proliferative response in all the strains tested. On the other hand, no proliferative response was observed with the dimers of the three RESA repeat sequences. The antibody levels in these strains immunized with RESA-CS hybrid structures showed high titres and a booster effect during subsequent immunization. Such a phenomenon was not observed with RESA peptides alone. The above CS sequence could be an ideal T-helper epitope which can be linked to hydrophilic B-cell epitopes of the RESA sequence to overcome major histocompatibility complex restriction in the host.