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PubMed1979

Development of Dipetalonema viteae third-stage larvae (Nematoda: Filarioidea) in micropore chambers implanted into jirds, hamsters, normal and immunized mice.

Development of third-stage larvae of Dipetalonema viteae within subcutaneously implanted micropore chambers proceeded in all hosts tested up to the fourth-stage larvae and occasionally to adolescent worms. In the jird the timing of development was comparable to a natural infection. Although the mouse is an insusceptible host, larval development could take place, but was very slow. Two intraperitoneal inoculations of living third-stage larvae into mice induced the production of antibodies against the larval cuticle and against common antigens. In such immune mice the development of third- and fourth-stage larvae within micropore chambers was significantly inhibited, larval mortality was increased, and the larval motility was impaired.

Animals↗
PubMed1995

Ultrastructure study of the excretory system and the genital primordium of the infective stage of Onchocerca volvulus (Nematoda:Filarioidea).

The electron microscopic investigation of the anterior part of the infective third-stage juvenile of Onchocerca volvulus provides first insights into the structure of the excretory system of this developmental stage of the parasite. The most anterior part of this system consists of a cell process of the syncytial excretory cells. At this height the excretory cells enclose the cuticle-lined excretory channel. The channel is in the process of elongation in the anterior-posterior direction, indicated by cell division in this region. More posteriad an ampulla-like structure is forming in the cytoplasm of the excretory cells. The inner surface of this ampulla is lined with a small number of single microvilli. In this part of the system the cytoplasm of the excretory cells is rich in Golgi bodies and endocytic vesicles. The ampulla has direct access to the exterior by the excretory duct. The excretory duct is a cuticle-lined structure surrounded by supporting fibres of an additional cell. This duct cell connects the excretory duct to the body-wall cuticle at the excretory pore. Adjacent to the region of the excretory system a cell is found that resembles a gland cell. This cell is in close contact to the ventral nerve cord. The genital primordia of the third-stage juvenile consist of several dividing cells. The female genital primordium is seen at the junction of the muscular with the glandular oesophagus and the male primordium can be found at the junction of the glandular oesophagus with the gut.

Animals↗
PubMed1992

Dose-dependent recovery of adult Acanthocheilonema viteae (Nematoda: Filarioidea) after single and trickle inoculations in jirds.

Increasing single doses of 5, 15, 30, 60 and 90 third-stage Acanthocheilonema viteae larvae per animal were inoculated into jirds. The adult worm load increased steadily, whereas the recovery rate decreased significantly, i.e. the correlation between dose and recovery was negative (rs, -0.90; n = 5; alpha, 0.05). The same inoculation doses were given as trickle inoculations of 5 L3 each (3 x 5, 6 x 5, 12 x 5, 18 x 5) at intervals of 2-6 days throughout the prepatency period. Irrespective of the number of repeated inoculations, a rather constant but low load of 7-10 worms/animal was reached. The recovery rate decreased drastically (rs, -1.0; n = 5). When trickle inoculations were carried out in animals exhibiting patient infections, the superinoculated larvae seemed to be destroyed almost completely; thus, a parasite-host equilibrium was guaranteed in all cases. The immunological background is discussed.

Animals↗
PubMed1993

Ultrastructural observations on the nervous system and the sensory organs of the infective stage (L3) of Onchocerca volvulus (Nematoda: Filarioidea).

A detailed morphological investigation of the sensory organs and the nervous system of the third juvenile stage of Onchocerca volvulus was performed at the ultrastructural level. A complex system of different receptor cells is found at the anterior and posterior end of this developmental stage. The eight papillae are arranged in two concentric circles consisting of two types of morphologically different receptors. Accessory nerve processes end free in the tip of the head. The paired amphids contain nine dendritic processes and accessory axons are seen in the surrounding cells. The basic structure of the amphids and of the circumoesophageal nerve ring is similar to that of other filarial nematodes. Two presumably neurosecretory cells are associated with the nerve ring. The reticular cytoplasm of these cells merges with the rough-surfaced endoplasmic reticulum of the lateral hypodermal chord. The paired phasmids at the posterior end of the developmental stages consist of single modified cilia that are embedded in an electron-dense mass. The receptor cell has access to the outside by a channel ending with a cuticular pore.

Animals↗
PubMed1985

The isolation and immunogenicity of the cuticle of Dipetalonema viteae (Filarioidea).

The cuticle of the filaria Dipetalonema viteae was isolated by sonication in 1% sodiumdodecylsulphate (SDS) and in a mixture of 1% SDS and 5% B-mercaptoethanol (BME). Sonication in SDS removed all internal parts and left the cuticle intact; this was verified by light- and electronmicroscopy. Sonication and incubation of the cuticle in the mixture of SDS-BME at pH 6.8 dissolved the basal and part of the median zone of the cuticle. The epicuticle and the cortical zone remained intact. The extracts were investigated using SDS-polyacrylamide gel electrophoresis; the early extracts contained a wide variety of proteins, whereas the later steps showed a consistent pattern with a smaller number of bands. Cuticles after SDS-purification, the extract of cuticular material in SDS-BME, and the cuticles insoluble in SDS-BME were used to immunize mice; the antibodies produced were visualized by an indirect fluorescent antibody test on cryostat sections of female worms. When SDS-purified cuticles were used for immunization, antibodies directed against all organs in the filariae were found. The SDS-BME extract and the insoluble cuticular pellet stimulated the production of antibodies restricted to the cuticle of adult worms and microfilariae. The purification method opens up the possibility of further isolation and characterization of antigens from the cuticle.

Animals↗
PubMed2006

Cytochemical characterization of the third-stage larva of Wuchereria bancrofti (Nematoda: Filarioidea).

In the present paper, we report the results we obtained using several cytochemical techniques to analyze the infective larva of Wuchereria bancrofti. An imidazole osmium tetroxide solution was used to visualize unsaturated fatty acids. A highly contrasted material forming a continuous structure was observed on the larval surface and over the epicuticle. A strong reaction was observed on the esophagus and also on the inner secreted material. Carbohydrates containing vic-glycol groups were not observed on the cuticle of the third-stage larva of W. bancrofti submitted to the Thiéry technique. Using a panel of eight gold-labeled lectins, we found that the cuticle exhibited slight labeling with all lectins used, indicating residues of N-acetyl-D: -glucosamine, N-acetyl-galactosamine, D: -galactose, D: -manose, and L: -fucose. Surface anionic sites were visualized by using cationized ferritin particles. Treatment with trypsin partially inhibited the reaction, whereas the treatment with chondroitinase ABC, a specific enzyme for glycosaminoglycans, completely abolished the labeling with cationic particles.

Animals↗
PubMed1997

The anterior central nervous system of male Onchocerca volvulus (Nematoda:Filarioidea) as a target for chemotherapy: results of an electron microscopy study.

An electron microscopy study was performed to evaluate the feasibility of the use of the anterior nerve ring of male Onchocerca volvulus for the assessment of early drug effects. Worms were exposed to new and known compounds at reasonable concentrations of 1 microM and less for 6, 12, 18, and 36 h in an established in vitro system. The anterior end of the filariae up to a length of 1 mm was examined and the morphological findings were compared with motility and reduction of a tetrazolium sat to formazan by live but not dead worms. The nerve fibers were more susceptible to the chemotherapeutic intervention then the other tissues in the anteriormost part of the worms. The alterations depended on the duration of exposure and the chemical nature of the compounds used. Morphological changes in the nervous tissue and the inhibition of motility and formazan production corresponded well for the arsenical mel w, used as an active standard, two pyrimidinyl-guanidines (PD 105482 and PD 105666), and an imidazolinylhydrazone (WR 251993).

Animals↗
PubMed1997

Electron microscope observations on Onchocerca ochengi and O. fasciata (Nematoda:Filarioidea).

The fine structure of the females and males of Onchocerca ochengi (parasitizing zebu and cattle) and of the females of O. fasciata from camels were described and compared to other filariae of the genus Onchocerca. It was shown that O. ochengi resembles O. volvulus of humans in its degree of development, while being more primitive than O. gibsoni. Besides other similarities O. ochengi attracts inflammatory cells in the way of O. volvulus and these could be a model for chemotherapeutic trials.

Animals↗
PubMed1989

Cytochemical demonstration of lectin binding-sites in the cuticle and tissues of Acanthocheilonema viteae (Filarioidea).

The lectin-gold technique was used for the ultrastructural localization of lectin binding sites on thin sections of Lowicryl K4M embedded adult females, infective larvae and SDS-2-mercaptoethanol-insoluble cuticle components of Acanthocheilonema (Dipetalonema) viteae. Helix pomatia lectin (HPL) coupled to 14 nm gold particles, was used for the demonstration of N-acetyl-D-galactosamine-containing glycoconjugates. Triticum vulgaris (wheat germ) agglutinin (WGA) coupled to 10 nm gold particles after cross-linking to BSA or ovomucoid-gold after application of unlabeled WGA, demonstrated WGA binding sites (N-acetyl-D-glucosamine). With both lectins no surface labelling of the cuticle was observed, but subcuticular layers reacted positively. HPL-gold was bound to cuticular fibers, the matrix and to the electron dense layer within the cortical zone of the cuticle of female worms. WGA-gold complexes were bound mainly to the cuticle matrix and somatic tissues. The results support the hypothesis that tissue-dwelling parasitic nematodes have reduced their surface carbohydrates perhaps as a consequence of their parasitic life.

Acetylgalactosamine↗
PubMed1989

The detoxification of xenobiotic compounds by Onchocerca gutturosa (Nematoda: Filarioidea).

In common with other helminths O. gutturosa appears to lack cytochrome P450 linked phase 1 enzymes and so its ability to metabolize aromatic nuclei may be severely restricted. The parasite could reduce azo- but not nitro-compounds and low levels of epoxide hydrolase activity were also detected. Glutathione S-transferase was the only phase 2 enzyme which could be demonstrated in O. gutturosa. High levels of glyoxalase I and in particular glyoxalase II were found in the parasite, suggesting an important role for these enzymes in detoxification.

Animals↗
PubMed1991

Apodemus sylvaticus, a new host for Acanthocheilonema viteae (Nematoda: filarioidea).

Susceptibility of Apodemus sylvaticus and A. agrarius to infection with Acanthocheilonema viteae was compared with that of hamsters and jirds. Microfilaremia in A. sylvaticus was first noted on day 52 post-infection (p.i.) and lasted during the course of the study (up to day 150 p.i.). Maximum microfilaremic levels (female worm basis) of A. sylvaticus [mean +/- S.D. (n) = 690 +/- 1288(6)] were considerably higher than those of hamsters [16 +/- 18(6)] and jirds [51 +/- 25(5)]. Adult worm recovery in A. sylvaticus ranged from 2 to 40% of the number of infective larvae inoculated. Worm development in A. sylvaticus resembled that in hamsters and jirds. In contrast, microfilaremia was not detected in, nor adult worms recovered from A. agrarius throughout the study.

Animals↗
PubMed1995

Ultrastructural and cytochemical aspects of the cuticle of adult Wuchereria bancrofti (Nematoda: Filarioidea).

Because of the practical limitations of obtaining viable adult forms of the Wuchereria bancrofti, the major species responsible for human lymphatic filariasis, only few ultrastructural studies were carried out. Adult worms present the cuticle as the interface structure between host and parasite. Cuticle structure and the demonstration of the presence of basic proteins, lipids, small amounts of terminal carbohydrate residues, phospholipids and collagen in the cuticle was undertaken on thin sections of embedded parasites. Using immunocytochemical methods, antigenic epitopes similar to those found in the extra cellular matrix of vertebrates were localized on thin sections of the Lowicryl embedded adult filariae.

Animals↗
PubMed1995

Polyamine uptake by a rodent filariid, Acanthocheilonema viteae (Nematoda: Filarioidea).

Helminth parasites lack the capacity to synthesize polyamines de novo. With the view to characterise alternative pools for the replenishment of polyamines, uptake of spermidine and spermine, were studied in Acanthocheilonema viteae, a parasite known to infect rodents. Motile worms recovered from the subcutaneous tissues of experimentally infected Mastomys natalensis were incubated in vitro with radiolabelled polyamines for the uptake assays. A time-dependent, temperature-sensitive, energy-requiring and saturable-uptake of the polyamines was observed. Male worms exhibited better uptake than the females and spermidine influx occurred at a higher rate than for spermine. A marginal competition of spermine with spermidine uptake and vice-versa was noticed while putrescine did not compete with uptake of either polyamines. Methyl-glyoxal-bis-guanyl hydrazone and Berenil caused significant inhibition of spermidine as well as spermine uptake. Subcutaneous tissues of A. viteae infected animals exhibited markedly higher levels of polyamines compared with the tissues obtained from healthy animals. Filarial worms are thus equipped with multiple polyamine transport systems which may aid their growth and survival within the host.

Animals↗