Taenia solium tapeworms synthesize corticosteroids and sex steroids in vitro

Cysticercosis is a disease caused by the larval stage of Taenia solium cestodes that belongs to the family Taeniidae that affects a number of hosts including humans. Taeniids tapeworms are hermaphroditic organisms that have reproductive units called proglottids that gradually mature to develop testis and ovaries. Cysticerci, the larval stage of these parasites synthesize steroids. To our knowledge there is no information about the capacity of T. solium tapeworms to metabolize progesterone or other precursors to steroid hormones. Therefore, the aim of this paper was to investigate if T. solium tapeworms were able to transform steroid precursors to corticosteroids and sex steroids. T. solium tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were cultured in the presence of tritiated progesterone or androstenedione. At the end of the experiments the culture media were analyzed by thin layer chromatography. The experiments described here showed that small amounts of testosterone were synthesized from (3)H-progesterone by complete or segmented tapeworms whereas the incubation of segmented tapeworms with (3)H-androstenedione, instead of (3)H-progesterone, improved their capacity to synthesize testosterone. In addition, the incubation of the parasites with (3)H-progesterone yielded corticosteroids, mainly deoxicorticosterone (DOC) and 11-deoxicortisol. In summary, the results described here, demonstrate that T. solium tapeworms synthesize corticosteroid and sex steroid like metabolites. The capacity of T. solium tapeworms to synthesize steroid hormones may contribute to the physiological functions of the parasite and also to their interaction with the host.

Steroid synthesis by Taenia crassiceps WFU cysticerci is regulated by enzyme inhibitors

Cysticerci and tapeworms from Taenia crassiceps WFU, ORF and Taenia solium synthesize sex-steroid hormones in vitro. Corticosteroids increase the 17β-estradiol synthesis by T. crassiceps cysticerci. T. crassiceps WFU cysticerci synthesize corticosteroids, mainly 11-deoxycorticosterone (DOC). The aim of this work was to investigate whether classical steroidogenic inhibitors modify the capacity of T. crassiceps WFU cysticerci to synthesize corticosteroids and sex steroid hormones. For this purpose, T. crassiceps WFU cysticerci were obtained from the abdominal cavity of mice, pre-cultured for 24h in DMEM+antibiotics/antimycotics and cultured in the presence of tritiated progesterone ((3)H-P4), androstendione ((3)H-A4), or dehydroepiandrosterone ((3)H-DHEA) plus different doses of the corresponding inhibitors, for different periods. Blanks with the culture media adding the tritiated precursors were simultaneously incubated. At the end of the incubation period, parasites were separated and media extracted with ether. The resulting steroids were separated by thin layer chromatography (TLC). Data were expressed as percent transformation of the tritiated precursors. Results showed that after 2h of exposure of the cysticerci to 100 μM formestane, the (3)H-17β-estradiol synthesis from tritiated androstenedione was significantly inhibited. The incubation of cysticerci in the presence of (3)H-DHEA and danazol (100 nM) resulted in (3)H-androstenediol accumulation and a significant reduction of the 17β-estradiol synthesis. The cysticerci (3)H-DOC synthesis was significantly inhibited when the parasites were cultured in the presence of different ketoconazole dosis. The drug treatments did not affect parasite's viability. The results of this study showed that corticosteroid and sex steroid synthesis in T. crassiceps WFU cysticerci can be modified by steroidogenic enzyme inhibitors. As was shown previously by our laboratory and others, parasite survival and development depends on sex steroids, therefore the inhibition of their synthesis is a good starting point exploited in situations where the inhibition of steroidogenesis could help to control the infection for the development of new treatments, or replacement of the usual therapy in resistant parasite infections. We raise the possibility that these drug actions may be beneficially.

Taenia crassiceps WFU cysticerci synthesize corticosteroids in vitro: metyrapone regulates the production

Taenia solium and Taenia crassiceps WFU cysticerci and tapeworms have the ability to synthesize sex steroid hormones and have a functional 3β-hydroxisteroid dehydrogenase. Corticosteroids (CS) like corticosterone and dexamethasone have been shown to stimulate in vitro estrogen production by Taenia crassiceps WFU cysticerci. The aim of this work was to study the ability of T. crassiceps WFU cysticerci to synthesize corticosteroids, and the effect of the inhibitor metyrapone on the CS synthesis. For this purpose T. crassiceps WFU cysticerci were obtained from the abdominal cavity of mice, thoroughly washed and pre-incubated in multiwells for 24 h in DMEM plus antibiotics/antimycotics. The tritiated CS precursor progesterone ((3)H-P4) was added to the culture media and parasites cultured for different periods. Blanks containing the culture media plus the (3)H-P4 were simultaneously incubated. Blanks and parasite culture media were ether extracted and analyzed by thin layer chromatography (TLC) in two different solvent systems. Corticosterone production was measured in the culture media by RIA. In some experiments metyrapone (0.1-0.5 mM) was added for 24, 48 or 72 h. Results showed that cysticerci mainly synthesized tritiated 11-deoxy corticosterone (DOC) and small amounts of corticosterone that was also detected by RIA. Small amounts of (3)H-11-deoxy cortisol were also found. Corticosteroid synthesis was time dependent. The addition of metyrapone significantly inhibited tritiated DOC, deoxycortisol and corticosterone synthesis. These results show for the first time that parasites have the capacity to synthesize CS that is modulated by metyrapone. Data suggest that DOC is the main corticosteroid in the parasites.

Taenia crassiceps: chloride currents expressed in Xenopus oocytes upon injection of mRNA of cysticerci (WFU strain) isolated from mice

To study the properties of ion channels of the tapeworm Taenia crassiceps, mRNA was isolated from cysticerci and injected into mature oocytes of the frog Xenopus laevis and ion currents were recorded four days after injection with the two-electrode voltage clamp technique. Oocytes injected with mRNA of T. crassiceps expressed outward currents (I(TC)) that activated instantly after onset of the test pulse, followed by a slow inactivation at potentials over +40 mV, with a reversal potential of -23.2+/-5 mV. They were not affected by changes on monovalent cationic composition of external media, but replacement of external chloride by gluconate shifted significantly the reversal potential, suggesting that I(TC) are anion currents, with a permeability sequence of NO3->Cl(-)>I(-)>>Gluconate. These currents were sensitive to changes of external pH but not to hypotonic challenges. They were significantly inhibited by DIDS, NPPB and Niflumic acid, but not by 9-anthracene. These results suggest that I(TC) are the result of expression of anion channels from the tapeworm T. crassiceps.

Excitability changes in human forearm corticospinal projections and spinal reflex pathways during rhythmic voluntary movement of the opposite limb

Rhythmic movements brought about by the contraction of muscles on one side of the body give rise to phase-locked changes in the excitability of the homologous motor pathways of the opposite limb. Such crossed facilitation should favour patterns of bimanual coordination in which homologous muscles are engaged simultaneously, and disrupt those in which the muscles are activated in an alternating fashion. In order to examine these issues, we obtained responses to transcranial magnetic stimulation (TMS), to stimulation of the cervicomedullary junction (cervicomedullary-evoked potentials, CMEPs), to peripheral nerve stimulation (H-reflexes and f-waves), and elicited stretch reflexes in the relaxed right flexor carpi radialis (FCR) muscle during rhythmic (2 Hz) flexion and extension movements of the opposite (left) wrist. The potentials evoked by TMS in right FCR were potentiated during the phases of movement in which the left FCR was most strongly engaged. In contrast, CMEPs were unaffected by the movements of the opposite limb. These results suggest that there was systematic variation of the excitability of the motor cortex ipsilateral to the moving limb. H-reflexes and stretch reflexes recorded in right FCR were modulated in phase with the activation of left FCR. As the f-waves did not vary in corresponding fashion, it appears that the phasic modulation of the H-reflex was mediated by presynaptic inhibition of Ia afferents. The observation that both H-reflexes and f-waves were depressed markedly during movements of the opposite indicates that there may also have been postsynaptic inhibition or disfacilitation of the largest motor units. Our findings indicate that the patterned modulation of excitability in motor pathways that occurs during rhythmic movements of the opposite limb is mediated primarily by interhemispheric interactions between cortical motor areas.

Ultrastructural damage of Trypanosoma cruzi epimastigotes exposed to decomplemented immune sera

The susceptibility of Trypanosoma cruzi epimastigotes to lysis by normal or immune sera in a complement-dependent reaction has been reported, but the effects induced directly by immune serum depleted of complement remain unstudied. The aim of this work was to study the ultrastructural alterations induced in T. cruzi epimastigotes by immune mouse or rabbit sera with or without complement. A local isolate of T. cruzi (Queretaro) was used in all experiments. Immune sera were raised in both mouse and rabbit by immunization with T. cruzi epimastigote antigens. Light microscopy showed intense agglutination of epimastigotes when incubated with decomplemented mouse or rabbit immune sera. A distinctive ultrastructural feature of this agglutination pattern was the fusion of plasma membranes and a pattern of intercrossing between subpellicular microtubules. Agglutination was associated with fragmentation of nuclear membranes and swelling of cytoplasm, Golgi cisternae, endoplasmic reticulum, mitochondria and kinetoplast membranes. Agglutinated parasites also incorporated trypan blue stain. Results of [3H]-thymidine incorporation confirmed that epimastigotes exposed to specific antibodies in the absence of complement were incapable of proliferating. Ultrastructural changes observed in epimastigote micrographs incubated with decomplemented immune mouse sera were statistically significant (P<0.001) when compared with results obtained from images after incubation with decomplemented normal mouse sera.

Taenia solium: germinal cell precursors in tapeworms grown in hamster intestine

BACKGROUND

In a previous study, it was shown that growth of evaginated metacestodes occurs in the germinative tissue of the neck by duplication of somatic stem cells. In these specimens, it was not possible to find the mitotic figures required to demonstrate duplication of germ cell lines.

METHODS

Taenia solium strobilae were collected from the intestinal lumen of outbred hamsters infected orally with 10 metacestodes dissected from naturally infected pigs. Animals were anesthetized 1-10 days postinfection, the small intestine excised, submerged in PBS, and cut open longitudinally. Live Taenias were incubated for 6-8 h in medium containing colchicine or 3H-thymidine, washed, and embedded for electron microscopy. For light microscopy and autoradiography, longitudinal sections were cut from whole blocks and mounted on glass slides. A population of large cells without nuclear membranes and containing discrete aggregates of chromatin were observed apposed to myofibrils in the germinative tissue of the neck. These cells were confirmed by electron microscopy as metaphase mitotic figures, with chromosomes attached to a microtubular spindle, embedded in cytoplasm, without a nuclear membrane, and with characteristic centrioles.

RESULTS

Only tapeworms in which 3H-thymidine was injected directly into the worm tissue by microsyringe were positive by autoradiography, demonstrating that in contrast to evaginated metacestodes, intestinal worms do not transport thymidine across the tegument.

CONCLUSIONS

The results show that differentiating T. solium worms have a subset of stem cells that require passage through a mammalian host to go into mitosis, and that tapeworms grown in an experimental animal do not take up 3H-thymidine in vitro.

Formation of calcareous corpuscles in the lumen of excretory canals of Taenia solium cysticerci

Platyhelminths, like many other organisms, are capable of producing mineral concretions. In cestodes these are referred to as calcareous corpuscles. Studies on these concretions in different cestodes both in vivo and in vitro have resulted in a number of hypotheses on their origin, formation, and structure. Calcareous corpuscles are believed to be of cellular origin, although the kind of cell involved and the mechanisms of mineralization remain under discussion. In the present paper we show that formation of calcareous corpuscles in cysticerci of Taenia solium is not of intracellular origin, as described for other cestodes, but occurs extracellularly in the lumen of protonephridial ducts in a way similar to that proposed for trematodes. This finding enhances the function of the protonephridial ducts, at least in the larvae of T. solium, to the roles formerly ascribed to the calcareous corpuscles.

Clinical manifestations and immunodiagnosis of gnathostomiasis in Culiacan, Mexico

Gnathostomiasis was first described in Mexico in 1970, and endemic areas have been spreading in six states of this country. In Culiacan, Sinaloa, 300 cases of cutaneous larva migrans were recorded between January 1992 and December 1995. In addition, a Gnathostoma larva was surgically removed from the eye of one patient. Cutaneous lesions were observed mainly on the face, neck, arms, and legs. About 70% of the patients showed eosinophilia. A skin biopsy was carried out on 35 patients and the parasite was identified in histopathologic sections of 12 of these patients. In four patients, the larva migrated out spontaneously from the skin. An enzyme-linked immunosorbent assay using a crude somatic extract of adult Gnathostoma doloresi worms showed that 93% of the patients were seropositive, confirming the reliability of clinical diagnosis. A total of 14 advanced third-stage Gnathostoma larvae were found in four species of ichthyophagous birds captured on dams and dikes near the city of Culiacan. Scanning electron micrographs of human and bird larvae showed that they were morphologically indistinguishable from G. spinigerm. We conclude that the life cycle of Gnathostoma has been established in Sinaloa, and has become a serious public health issue for residents.

Taenia solium: description of the intestinal implantation sites in experimental hamster infections

Experimental infections in golden hamsters with viable Taenia solium metacestodes were used to study by light and electron microscopy the implantation site of the adult tapeworm in the intestinal wall. Implantation sites from 3-, 4-, 10-, and 40-day infections were located in the upper third of the duodenum, excised and fixed in Zenker's or Karnovsky's solution, embedded in Polybed resin, and sectioned longitudinally to observe the position of the worm on the intestinal wall. The scolex of the tapeworm was situated between host villi, with the rostellum penetrating the intestinal wall and the suckers entrapping adjacent villi. Serial sections through several whole implantation sites revealed that the worm was anchored to the host by all 4 suckers simultaneously, each of which was located at a different level and had entrapped intestinal villi in its cavity. Host tissue within the suckers was damaged, exhibiting various degrees of cell lysis and necrosis of epithelial and submucosal cells. The tegumentary surface and microtriches of the scolex were well preserved, with occasional coalescence of tegumentary microvesicles in 10- and 40-day-old infections; microtriches were in direct contact with the damaged host tissue. This study is the first morphological and ultrastructural description of the attachment of T. solium to the intestinal wall employing an experimental model, the results of which may contribute to a better understanding of the biology of human tapeworm infections.

Host cells in the spiral canal of Taenia solium (Cestoda) cysticerci

The presence of host inflammatory cells inside the spiral canal of all viable Taenia solium cysts obtained from naturally infected pigs is described. Cells can penetrate into the vicinity of suckers and rostellum, although most appear damaged, suggesting that conditions in the canal are deleterious for them. These observations extend the localization of host inflammatory infiltrate to this intricate microniche, which may offer new approaches for the treatment of cysticercosis, based on a scolex-targeted action. The presence of host cells in the canal of cysts also poses the problem of the resulting contamination with host materials in studies using cysts extracts. As an example, host DNA contamination is readily detectable in genomic DNA isolated from T. solium and Taenia taeniaeformis cysts, as demonstrated by polymerase chain reaction amplification and subsequent sequencing of a segment of the 18S ribosomal gene.

Autoradiographic analysis of the germinative tissue in evaginated Taenia solium metacestodes

Evaginated Taenia solium metacestodes dissected from infected pork meat were incubated in vitro in RPMI 1640 medium with tritiated thymidine, washed, and further incubated for various chase periods. Worms were fixed and embedded in Poly/Bed and sections were processed for autoradiography. Results showed that all longitudinal sections had a germinative region located 500-700 mm posterior to the apex of the scolex with tegumentary cytons arranged in staggered columns perpendicular to the tegument. After 6-hr pulse and 0-12-hr chase periods, a large number of labeled cells were found in the parenchyma and tegumentary wall, included were myocytons, calcareous corpuscle cells, flame cells, osmoregulatory channel cells, and, in the medullary parenchyma, labeled undifferentiated round cells with a large nucleus, prominent nucleolus, abundant ribosomes, and no cytoplasmic organelles. These undifferentiated cells were not labeled after 24-hr and 48-hr chase periods, an observation that strongly suggests these cells divide and migrate toward the tegument in a pattern similar to that described for other cestodes. The morphology and localization of these cells support the view that they are stem cells that give rise to the various cell types of the tegumentary wall. The results indicate that T. solium contains a germinative tissue similar to that described in other cestodes, in which stem cells proliferate continuously, differentiate, and migrate to the tegument, constituting the main process by which these worms develop from metacestode to the adult stage.

Immunosuppression and inhibition of inflammation in mice induced by a small Taenia solium RNA-peptide to implanted T. solium metacestodes

Subcutaneous implantation of Taenia solium metacestodes in mice induces an inflammatory reaction made up mainly of neutrophils and eosinophils after 12 days. Administration of a small RNA-peptide (metacestode factor, MF) purified from T. solium metacestodes significantly reduces the inflammatory site in both size and composition, yielding a very low number of eosinophils. The metacestodes implanted in control mice were completely destroyed and their remnants were surrounded by an intense inflammation predominantly made up of neutrophils and eosinophils. In contrast, metacestodes implanted in mice treated with MF showed apparently intact suckers, rostellum, hooks, and tegument. Inhibition of inflammation around the parasites was also observed in mice immunized with T. solium metacestode antigens and inoculated simultaneously with MF. Mice immunized only with T. solium metacestode antigens produced a granulomatous process around metacestodes that destroyed most of the large metacestode structures: suckers, rostellum, hooks, and tegument-wall tissues. Furthermore, treatment of mice with MF or implanted metacestodes decreased the antibody (P < 0.05) and cellular responses (P < 0.05) to metacestode antigens. The antibody responses was even lower when both of these treatments were given simultaneously. These findings support the idea that MF plays a key role in the down-regulation of the host immune response, contributing to the parasite's survival.

Fermentative and aerobic metabolism in Rhizobium etli

Strains of Rhizobium etli, Rhizobium meliloti, and Rhizobium tropici decreased their capacity to grow after successive subcultures in minimal medium, with a pattern characteristic for each species. During the growth of R. etli CE 3 in minimal medium (MM), a fermentation-like response was apparent: the O2 content was reduced and, simultaneously, organic acids and amino acids were excreted and poly-beta-hydroxybutyrate (PHB) was accumulated. Some of the organic acids excreted into the medium were tricarboxylic acid (TCA) cycle intermediates, and, concomitantly, the activities of several TCA cycle and auxiliary enzymes decreased substantially or became undetectable. Optimal and sustained growth and a low PHB content were found in R. etli CE 3 when it was grown in MM inoculated at a low cell density with O2 maintained at 20% or with the addition of supplements that have an effect on the supply of substrates for the TCA cycle. In the presence of supplements such as biotin or thiamine, no amino acids were excreted and the organic acids already excreted into the medium were later reutilized. Levels of enzyme activities in cells from supplemented cultures indicated that carbon flux through the TCA cycle was maintained, which did not happen in MM. It is proposed that the fermentative state in Rhizobium species is triggered by a cell density signal that results in the regulation of some of the enzymes responsible for the flux of carbon through the TCA cycle and that this in turn determines how much carbon is available for the synthesis and accumulation of PHB. The fermentative state of free-living Rhizobium species may be closely related to the metabolism that these bacteria express during symbiosis.

Purification and ultrastructural localization of surface glycoproteins of Taenia solium (Cestoda) cysticerci

A glycoprotein-enriched fraction was obtained by Concanavalin A-Sepharose 4B affinity chromatography from a crude extract of T. solium cysticerci. The six most prominent glycoproteins with molecular sizes of 180, 103, 96, 68, 55 and 45 kDa were purified by electro-elution from polyacrylamide gel slices. Ultrastructural localization assays using hyperimmune rabbit sera to each glycoprotein, demonstrated their presence on the tegumentary surface of the bladder wall of T. solium cysticerci. Similar studies showed that the 180 kDa glycoprotein is also present on the surface of the T. solium and T. saginata adult worms, as well as in T. saginata, T. pisiformis and T. crassiceps cysticerci. The 55 kDa glycoprotein, which is one of the most abundant on the cyst surface, was found to correspond to the heavy chain of pig IgG by Western blotting.

Taenia solium taeniasis and neurocysticercosis in a Mexican rural family

A case of neurocysticercosis in a six-year-old Mexican boy and a case of Taenia solium taeniasis in his five-year-old brother are reported. Neurocysticercosis was suspected based on clinical findings and was confirmed by computed tomography scanning. A parasitologic examination with zinc-sulfate flotation and formalin-ether sedimentation techniques was carried out on the whole family, and revealed Taenia sp. eggs in three stool samples from the five-year-old boy. The entire family agreed to undergo chemotherapy with niclosamide, but only the child passing taeniid eggs eliminated T. solium. No additional taeniasis cases were found in an examination of 20% of the village population, using the same parasitologic techniques. The results of an ELISA using cysticercus antigens were negative for the boy with neurocysticercosis, for other family members, and for 24 village volunteers, but were positive for the T. solium tapeworm carrier. It was concluded that in this family, person-to-person transmission of the tapeworm occurred due to poor living conditions and hygiene.

Epidemiologic study and control of Taenia solium infections with praziquantel in a rural village of Mexico

This study reports the results of an epidemiologic survey for the detection of Taenia solium in a rural village of 559 inhabitants in Sinaloa, Mexico, as well as a large scale treatment of the population with praziquantel. The study was carried out in two stages. In stage 1, serial stool analysis of 392 persons detected a cluster of three T. solium tapeworms. A fourth T. solium tapeworm was detected through a household census, giving a 1.32% prevalence rate for this helminth. Over 70% of the population over five years of age was treated with a 10 mg/kg dose of praziquantel, and no additional tapeworms were found. Environmental studies for the detection of Taenia sp. eggs in soil, water, and and objects from the houses of tapeworm-infected individuals showed only one soil sample containing eggs compatible with Taenia sp. A total of 72 domestic pigs were examined for the presence of cysticerci under the tongue. One animal had cysts, and belonged to a household that had two T. solium tapeworm infections. Stage 2 of the study was carried out one year after large scale antihelminthic treatment (LSAT), and no infections with Taenia sp. eggs were found. No cysticercus-infected pigs were detected. Intestinal parasitosis decreased from 69.2% to 37.5%. It is concluded that LSAT with praziquantel is efficient in decreasing endemic foci of T. solium. Seropositivity to T. solium bladder fluid antigens was tested by enzyme-linked immunosorbent assay and found to be 11% before LSAT and 7% one year later. In family members living with T. solium tapeworm carriers, the number of seropositive individuals was 28%. The relative risk ratio of seropositivity for persons living in the same household with a T. solium tapeworm carrier was 2.95. Positive response was significantly higher in the 30-39-year-old age group, in which 30% were seropositive in stage 1, compared with 7% one year after LSAT. High seropositivity rates were significantly associated with tapeworm clusters as well as with individuals with a clinical history of seizures.

Paramyosin is the Schistosoma mansoni (Trematoda) homologue of antigen B from Taenia solium (Cestoda)

Antigen B, a major antigen of the cestode parasite Taenia solium, has been purified and a portion of amino acid sequence obtained. Paramyosin of the trematode parasite Schistosoma mansoni, an immunogenic protein that has shown promise as a vaccine candidate, has several biochemical and immunological properties in common with antigen B. A full-length cDNA clone of S. mansoni paramyosin has been obtained and the predicted translation product contains a sequence that is highly homologous to the sequence obtained for antigen B. The predicted amino acid composition and isolectric point of paramyosin are nearly identical to those established for antigen B. Recombinant S. mansoni paramyosin, expressed in Escherichia coli as a fusion protein with beta-galactosidase, was recognized by antisera against T. solium antigen B. We conclude from these results that S. mansoni paramyosin and T. solium antigen B are homologous proteins. Since S. mansoni paramyosin is thought to be a muscle protein and T. solium antigen B a secreted glycoprotein with anti-complement activity, this conclusion raises some interesting questions regarding the role of this class of proteins in the host-parasite relationship.

Crystals of virus-like particles in the metacestodes of Taenia solium and T. crassiceps

Crystals of virus-like particles (VLP) are described as occurring in the nuclei of damaged tegumentary cytons from carcasses of Taenia solium metacestodes that had been stripped of their teguments. The VLP are grouped as parallel lines of round particles in an hexagonal packaging of spheroids forming small or large crystals. The individual particles have an external diameter of 36-37 nm and a wall of 5-6 nm thick, which surround a cavity of lower electron density. As identical crystals were also observed in normal tissues of T. solium and of T. crassiceps, it is suggested that both species of cysticerci are normal carriers of a similar species of virus. The possible biological implications of this condition are discussed.

Serology as an indicator of Taenia solium tapeworm infections in a rural community in Mexico

Serial stool examinations were carried out on a sample of 516 persons living in the town of El Salado (1993 inhabitants). In a group of 40 families (198 individuals), selected by random sampling, there were 2 cases of Taenia solium infection (1.2%); an additional group of 67 families (318 individuals), who volunteered for the study, had 4 cases (1.1%). 5 of the 6 T. solium cases were clustered in 4 neighbouring households. Serum antibodies to the larval stage of T. solium were detected by ELISA using bladder fluid as antigen. 22 members of the random sample group were positive (11%); 58 persons of the total sample of 478 were positive (12%). 43% of individuals living in the same household as a T. solium-infected person were positive, compared to 8.6% seropositive individuals among those not known to have been in daily contact with a T. solium carrier. Odds ratio analysis of the random and total samples showed that the risk of being seropositive when living in the same household as a tapeworm carrier was 9.05 and 6.85 respectively. The results showed a significant correlation between T. solium tapeworm clusters and higher seropositivity rates among contacts rather than among non-contacts. The immune response is a sensitive indicator of a tapeworm infection in a household or family, and is easier to determine than the traditional search for taeniid eggs in stool, a method which is difficult to apply in developing countries due to lack of trained personnel.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning and sequencing of two actin genes from Taenia solium (Cestoda)

Genomic and cDNA actin clones were isolated from Taenia solium gene libraries. The actin genes are interrupted by intervening sequences. Protein coding regions of both genes predict the same amino acid sequence. cDNA sequence data indicate that at least one gene is expressed at the larval stage. Results from Northern and Western blots showed that T. solium expresses an actin transcript of about 1,400 bases and a protein of 45,000 Da.

Purification of antigen B from Taenia solium cysticerci by affinity to mammalian collagen

A 1-step procedure for the easy and rapid purification of milligram amounts of antigen B from a crude extract of Taenia solium cysticerci is described here. This procedure takes advantage of the property of the antigen B to bind to collagen and is based on antigen adsorption to polymeric collagen.

Histological and ultrastructural localization of antigen B in the metacestode of Taenia solium

The morphological localization of antigen B (AgB) in the tissues of the Taenia solium metacestode was studied by immunological and biochemical methods. Indirect immunofluorescence carried out on vibratome sections showed that AgB is widely distributed throughout the tissue. A more intense fluorescence was observed in the tegumentary cytons of the bladder wall and in the lumen of the spiral canal of the invaginated scolex. Ultrastructural analysis of larvae washed in PBS after dissection from meat and then incubated with rabbit antibodies against AgB, followed by peroxidase-labeled goat anti-rabbit IgG, did not exhibit electron-dense material on the external surface. Larvae fixed in glutaraldehyde immediately after dissection and exposed to the immunoperoxidase reagents did exhibit electron-dense material on microtriches, indicating that AgB is only loosely bound to the external surface. Crude extracts of surface-radioiodinated cysticerci analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) contained no labeled proteins with the molecular weight of AgB. Autoradiography of the immunoelectrophoretograms in which the crude extract was confronted with antibodies to AgB demonstrated that this antigen was not labeled, and therefore is not exposed on the tegumentary surface. The results suggest that AgB is synthesized by the tegumentary cytons of the parasite and secreted through the tegumental membrane into the host tissues and the lumen of the spiral canal.

Inhibition of mitogenesis induced by phytohemagglutinin and Lens culinaris lectin in adherent-cell supernatants treated with protein extract of Mycobacterium tuberculosis

Specific stimulation of T cells by phytohemagglutinin and Lens culinaris lectin was inhibited by a soluble factor(s) secreted by normal adherent cells stimulated with culture filtrate protein extract (CFPE) derived from bacterial cultures of Mycobacterium tuberculosis H37Ra (avirulent) and H37Rv (virulent). The induction of the inhibitory factor was blocked by the presence of hyperimmune antisera to H37Rv or H37Ra CFPE. The inhibitory factor did not seem to be a CFPE reprocessed by the adherent cells. Inhibitory activity was maximal in supernatants of adherent-cell cultures incubated for 48 h; the inhibitory factor was heat labile, and its production was dependent on the concentration of M. tuberculosis CFPE. A mouse monocyte-macrophage cell line, ATCC J774A.1, produced an identical inhibitory factor, thus excluding a non-macrophage-contaminating adherent cell as the source of the factor. This inhibitory factor also interfered with the recognition of phytohemagglutinin and Lens culinaris lectin by T cells.

Taenia solium: mitogenic effect of larval extracts on murine B lymphocytes

The effect of an extract (CE) obtained from Cysticercus cellulosae on the proliferation of lymphocytes was studied in cultures of murine spleen cells. The addition of CE to the cultures resulted in the highly significant uptake and incorporation of tritiated thymidine (3H-TdR) into DNA. This phenomena was dose-dependent, with doses lower and higher than the optimal concentration causing less marked effects. The kinetic peak of this response was found to occur on day 2 of culture. CE evoked a proliferative response in cultures of spleen cells from congenitally athymic (nu/nu) BALB/c mice. Cultures of bone marrow-derived (B) lymphocytes, generated by treatment of spleen cells with rabbit antithymocyte serum and complement, incorporated 3H-TdR to a degree similar to that of normal spleen cell cultures. CE did not induce the proliferation of thymocytes. To eliminate the possibility that the mitogenic effect of CE was due to LPS, we carried out experiments using Polymyxin B (PB). CE was mitogenic after treatment with PB which inactivated the LPD effect. In addition, CE elicited 3H-TdR uptake in spleen cells from the LPS nonresponsive C3H/HeJ mouse strain.

The inflammatory reaction surrounding Taenia solium larvae in pig muscle: ultrastructural and light microscopic observations

An inflammatory reaction with the general characteristics of a chronic granuloma surrounding Taenia solium larvae in pig muscle is described. Larvae with an inflammatory capsule were obtained at slaughter from pigs 6-8 months-of-age and were processed for light and electron microscopy. Eosinophils (granulocytes with orange staining and peroxidase-positive granules) were found to be degranulated and in close contact with the parasite surface. Histiocyte, epithelioid cells, macrophages and lymphocytes were also evident, as well as large numbers of plasma cells in the outer areas of the wall-circumscribed reaction. The parasites were ultrastructurally intact, with a normal tegument and only occasional changes in the microvesicles. The results are discussed with reference to parasite survival in the host.