Comparative analysis of a chemotherapy effect on the cuticular surface of Wuchereria bancrofti adult worms in vivo

Nematocidal effect of Piper retrofractum Vahl on morphology and ultrastructure of Strongyloides stercoralis third-stage infective larvae

In a previous research work aimed at discovering natural helminthicides as alternatives to conventional synthetic drugs, Piper retrofractum fruit hexane extract (PHE) has been shown to possess promising nematocidal activity against the third-stage infective larvae of Strongyloides stercoralis. Thus, this study was designed to evaluate the chemical composition and the impact of PHE on symptom and structural alterations of S. stercoralis. Chemical analysis of PHE by gas chromatography-mass spectrometry demonstrated 26 different compounds, constituting 100% of the total composition. The main components were 4-acetylphenyl (4-benzoylphenoxy) acetate (14.86%) and octyl methoxycinnamate (12.72%). Nematocidal bioassays revealed promising potential of PHE against S. stercoralis larvae, with an LC50 value of 0.059 mg/ml, while the reference drug ivermectin exerted higher efficacy, with an LC50 value of 0.020 µg/ml. Behavioural observations under light microscopy revealed that PHE-treated S. stercoralis larvae moved slowly, became paralysed and eventually died during 24 h of incubation. The dead larvae appeared under light microscope as straight worms with unknown vacuoles of different sizes inside their internal bodies. Morphological alterations of the PHE-treated S. stercoralis larvae, such as straight bodies with swollen cuticle, faded transverse annulations and faded longitudinal striations, as well as shallow and smooth lateral longitudinal grooves, were seen clearly under scanning electron microscopy. Ultrastructural changes in the treated larvae, such as protruded lateral longitudinal grooves, loose muscle with vacuolation, dissociation between the hypodermis and cuticle and marked intracellular disorganization with vacuolation, were detected under transmission electron microscopy. The results of this study provide evidence that PHE is toxic against S. stercoralis and also a potential new alternative for anti-Strongyloides chemotherapy.

Cuticular surface damage of Ascaridia galli adult worms treated with Veitchia merrillii betel nuts extract in vitro

Aim:

The objective of this research was to in vitro evaluate the cuticular surface damage of Ascaridia galli adult worms treated with ethanolic extract of betel nuts Veitchia merrillii.

Materials and Methods:

Phytochemical screening was done using FeCl₃, Wagner and Dragendorff reagents, NaOH, MgHCl, and Liebermann–Burchard reaction test. Amount of 16 worms were segregated into four groups with three replicates. Four worms of each group submerged into phosphate buffered saline, 25 mg/ml, and 75 mg/ml crude ethanolic extract of V. merrillii, and 15 mg/ml albendazole. The effect of these extract was observed 40 h after incubation as soon as worms death. The worms were sectioned transversally and were explored for any cuticular histopathological changes in their body surface under microscope.

Results:

We found that the ethanolic extract of V. merrillii betel nuts contains tannins, alkaloids, flavonoids, triterpenoids, and saponins. The ethanolic extract of betel nuts V. merrillii induces surface alterations caused cuticular damage of A. galli adult worms.

Conclusion:

We concluded that ethanolic extract of betel nuts V. merrillii possess anthelmintic activity caused cuticular damage of A. galli adult worms.

Profiling the macrofilaricidal effects of flubendazole on adult female Brugia malayi using RNAseq

The use of microfilaricidal drugs for the control of onchocerciasis and lymphatic filariasis (LF) necessitates prolonged yearly dosing. Prospects for elimination or eradication of these diseases would be enhanced by the availability of a macrofilaricidal drug. Flubendazole (FLBZ), a benzimidazole anthelmintic, is an appealing candidate. FLBZ has demonstrated potent macrofilaricidal effects in a number of experimental rodent models and in one human trial. Unfortunately, FLBZ was deemed unsatisfactory for use in mass drug administration campaigns due to its limited oral bioavailability. A new formulation that enables sufficient bioavailability following oral administration could render FLBZ an effective treatment for onchocerciasis and LF. Identification of drug-derived effects is important in ascertaining a dosage regimen which is predicted to be lethal to the parasite in situ. In previous histological studies, exposure to FLBZ induced damage to tissues required for reproduction and survival at pharmacologically relevant concentrations. However, more precise and quantitative indices of drug effects are needed. This study assessed drug effects using a transcriptomic approach to confirm effects observed histologically and to identify genes which were differentially expressed in treated adult female Brugia malayi. Comparative analysis across different concentrations (1 μM and 5 μM) and durations (48 and 120 h) provided an overview of the processes which are affected by FLBZ exposure. Genes with dysregulated expression were consistent with the reproductive effects observed via histology in our previous studies. This study revealed transcriptional changes in genes involved in embryo development. Additionally, significant downregulation was observed in genes encoding cuticle components, which may reflect changes in developing embryos, the adult worm cuticle or both. These data support the hypothesis that FLBZ acts predominantly on rapidly dividing cells, and provides a basis for selecting molecular markers of drug-induced damage which may be of use in predicting efficacious FLBZ regimens.

Comparison between the effect of Lawsonia inermis and flubendazole on Strongyloides species using scanning electron microscopy

Strongyloides species is a helminth of worldwide distribution primarily in tropical and subtropical regions. It is the only soil-transmitted helminth with the ability for autoinfection so; it may lead to severe systemic manifestations especially in immunosuppressed patients. Chemotherapy is currently considered the best therapeutic option for strongyloidiasis but some drugs are expensive and others have side effects as nausea, diarrhea and headache. Strongyloides larva is resistant to most chemical agents so, search for plant extracts may provide other effective but less expensive treatment. Lawsonia inermis Linn, popularly known as Henna, has been proven to have antihelminthic, antibacterial and antifungal properties. The current study was carried out to evaluate the efficacy of Lawsonia inermis on Strongyloides spp. In vitro using scanning electron microscopy. Fifty Strongyloides species. larvae and free living females were incubated with different concentrations of Lawsonia (1, 10, 100 mg/ml), for different incubation periods (24, 48, 72 and 96 h) in comparison to the same concentrations of flubendazole at the same different time points. The results showed that Lawsonia inermis in a concentration of 10 mg/ml incubated with Strongyloides spp. female for 24 h affected the parasite cuticular surface in the form of transverse and longitudinal fissures and transverse depression in comparison to no cuticular change with flubendazole (100 mg/ml). This suggests that Lawsonia inermis may be a promising phytotherapeutic agent for strongyloidiasis.

Identification and ultrastructural characterization of the Wolbachia symbiont in Litomosoides chagasfilhoi

BACKGROUND

Filarial nematodes are arthropod-transmitted parasites of vertebrates that affect more than 150 million people around the world and remain a major public health problem throughout tropical and subtropical regions. Despite the importance of these nematodes, the current treatment strategies are not efficient in eliminating the parasite. The main strategy of control is based on chemotherapy with diethylcarbamazine, albendazole and ivermectin. In the 1970s, it was found that some filarids possess endosymbiotic bacteria that are important for the development, survival and infectivity of the nematodes. These bacteria belong to the genus Wolbachia, which is a widespread and abundant intracellular symbiont in worms. Knowledge about the structure of the bacteria and their relationship with their nematode hosts may allow new perspectives for the control of filarial nematodes.

METHODS

In this study, we used transmission electron microscopy combined with three-dimensional approaches to observe the structure of the endosymbiont of the filarial nematode Litomosoides chagasfilhoi, an experimental model for the study of lymphatic filariasis. In addition, the bacterium was classified based on PCR analyses.

RESULTS

The bacterium was mainly found in the hypodermis and in the female reproductive system in close association with host cell structures, such as the nucleus and endoplasmic reticulum. Our ultrastructural data also showed that the symbiont envelope is composed of two membrane units and is enclosed in a cytoplasmic vacuole, the symbiosome. Molecular data revealed that the bacterium of L. chagasfilhoi shares 100% identity with the Wolbachia endosymbiont of Litomosoides galizai.

CONCLUSIONS

Here we described ultrastructural aspects of the relationship of the Wolbachia with the filarial nematode Litomosoides chagasfilhoi and the findings lead us to consider this relationship as a mutualistic symbiosis.

Filarial infections in travelers and immigrants

Filarial infections including loiasis, onchocerciasis, and lymphatic filariasis are important causes of morbidity in endemic populations worldwide, and they present a risk to travelers to endemic areas. Definitive diagnosis is complicated by overlap in the geographic distribution and clinical manifestations of the different filarial parasites, as well as similarities in their antigenic and nucleic acid composition. This has important implications for treatment, because the efficacies and toxicities of available antifilarial agents differ dramatically among filarial species. Recent advances, including the visualization of adult filarial worms in vivo by high-frequency ultrasound and the identification of the bacterial endosymbiont, Wolbachia, have greatly improved our understanding of the pathogenesis of filarial infection and have led to novel approaches to the diagnosis and treatment of travelers and immigrants from filarial-endemic regions.

Imported bancroftian filariasis: diethylcarbamazine response and benzimidazole susceptibility of Wuchereria bancrofti in dynamic cross-border migrant population targeted by the National Program to Eliminate Lymphatic Filariasis in South Thailand

The implementation on the Thailand-Myanmar border of annual mass drug administration (MDA) of a single 6 mg/kg dose of diethylcarbamazine (DEC) plus 400mg albendazole, part of the National Program to Eliminate Lymphatic Filariasis (PELF), has been challenging. In particular, chain migration of cross-border Myanmar workers at risk for nocturnally periodic Wuchereria bancrofti infection can lead to imported bancroftian filariasis (IBF) in Thailand. IBF is targeted for multiple-dose MDA with 300 mg DEC, in addition to what is recommended by the World Health Organization (WHO). The dynamic Myanmar migrants in Phang-nga, southern Thailand were sampled to test whether the responsible W. bancrofti has a genetic predisposition of benzimidazole exposure, and IBF exhibits DEC susceptibility. The long-term migrants had more access to DEC. IBF in W. bancrofti antigenemic (microfilaremic vs. amicrofilaremic) short-term migrants exhibited susceptibility to a 300-mg single-dose DEC treatment. During the course of a 3-month follow-up, antigenemia was significantly reduced, but microfilaremia was fluctuated. Surprisingly, a newly recognized Mansonella infection co-existing among W. bancrofti-affected Myanmar migrants elicited microfilaremia clearance within a month after treatment. As a result of the presence of genetically stable W. bancrofti beta-tubulin (Wbtubb) gene responsible for benzimidazole susceptibility, IBF did not possess a genetic predisposition for benzimidazole exposure. Point mutations at positions Phe167Tyr and Phe200Tyr were not detected by Wbtubb locus-specific nested PCR and sequencing. This study has the potential to help guide not only the Thai/Myanmar PELF surveillance and monitoring of mass treatment impacts on W. bancrofti, but also the other endemic countries allied with the Global Program to Eliminate Lymphatic Filariasis (GPELF).