On the relationship between incorporation of32P into phospholipids and binding of beta-adrenoceptor blocking drugs to isolated mast cells

The lipophilic beta-adrenoceptor blocking drugs exaprolol and propranolol significantly decreased the incorporation of³²P into phosphatidylethanolamine, phosphatidylcholine and phosphatidylinositol of isolated rat mast cells. In contrast, the hydrophilic drugs metipranolol, practolol and atenolol increased the incorporation of³²P into phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. The inhibition of³²P incorporation by lipophilic drugs correlated with the high binding of these drugs to mast cells.     

Preliminary studies of lipids of the trematodes Eurytrema pancreaticum,Calicophoron erschowi and the turbellarian Penecurva sibirica

The amount of total lipids, phospholipids, neutral lipids and fatty acids was determined in cattle parasites, namely the trematodes Eurytrema pancreaticum, Calicophoron erschowi, and in the free-living turbellarian Penecurva sibirica. Neutral lipids of these flatworms contained sterols, sterol esters, triacylglycerols and free fatty acids. P. sibirica also contained diacylglycerols.Parasitic and free-living flatworms differed in phospholipid composition: the turbellarian did not contain phosphatidylserine, and the trematodes had practically no sphingomyelin or lysophosphatidyl choline. E. pancreaticum, C. erschowi and P. sibirica contained high levels of phosphatidylcholine and phosphatidylethanolamine as well as lysophosphatidylethanolamine and cardiolipin.The fatty acid composition of total lipid extracts of flatworms and of the pancreas and rumen of the host animals were determined. The fatty acid composition of the flatworm lipids reflected the fatty acid composition of the host tissue but was not identical to it.     

Detection of Schistosoma mansoni Membrane Antigens by Immunoblot Analysis of Sera of Patients from Low-Transmission Areas

Schistosoma mansoni surface membrane components play a relevant role in the host-parasite interaction, and some are released in vivo as circulating antigens. n-Butanol extraction favors the release of membrane antigens like alkaline phosphatase, which has been shown to be specifically recognized by antibodies from S. mansoni-infected humans and animals. In the present study, components in the n-butanol extract (BE) of the adult S. mansoni worm membrane fraction were separated by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D SDS-PAGE [15%]) and further analyzed by immunoblotting (immunoglobulin G) using defined sera. S. mansoni-infected patient sera, but not sera of uninfected patients or sera obtained from patients infected with other parasite species, specifically and variably recognized up to 20 polypeptides in the molecular mass range of ~8 to >80 kDa. There were some differences in the number, intensity, and frequency of recognition of the BE antigens among sera from Venezuelan sites of endemicity with a different status of schistosomiasis transmission. Antigens in the 28- to 24-kDa molecular mass range appeared as immunodominants and were recognized by S. mansoni-positive sera from all the sites, with recognition frequencies varying between 57.5 and 97.5%. Immunoblotting with BE membrane antigens resulted in a highly sensitive (98.1%), specific (96.1.0%), and confirmatory test for the immunodiagnosis of schistosomiasis in low-transmission areas.     

Lecithin biosynthesis in a clonal line of lung adenoma cells with type II alveolar cell properties

The content and synthesis of certain phospholipids associated with lung surfactant has been investigated in a clonal line of epithelial cells derived from mouse lung adenoma. These cells, designated LA-4, possess osmiophilic intracytoplasmic lamellar inclusion bodies similar in appearance to lamellar bodies observed in normal type 2 alveolar epithelial cells (Stoner et al., 1975).Lecithin was the most abundant phospholipid in the LA-4 cells, comprising more than 50% of all phospholipid. LA-4 cells had significantly higher contents of total lecithin than in vivo adenoma and normal lung, but a lower proportion (27–29%) of the total lecithin in disaturated form than normal lung (36%). In addition, LA-4 cells had a significantly higher proportion of total lecithin in disaturated form than a clonal line of mouse lung fibroblasts (14%). The content of phosphatidylglycerol in LA-4 cells was significantly lower than in normal lung.Radiolabeled precursor studies showed that palmitic acid was rapidly incorporated into disaturated lecithin of LA-4 adenoma cells and to a greater extent than glycerol, suggesting that the saturation pathways forming disaturated lecithins are active. Studies with radiolabeled choline and methionine suggest that LA-4 cells synthesize total and disaturated lecithins de novo principally through the choline incorporation pathway, with a minor contribution by the three-step methylation of phosphatidyl-ethanolamine.The present results indicate that the phospholipid metabolism of lung adenoma cells is preserved when cultured in vitro. Urethan-induced transformation of type 2 alveolar cells appears to result in a diminished capacity of the cells to synthesize phosphatidylglycerol and disaturated phosphatidylcholine.     

Uptake and incorporation of choline by Schistosoma mansoni adults

Choline uptake and incorporation into Schistosoma mansoni is used as a model for investigating transport across and formation of a double bilayer surface of a syncytial transporting epithelium. Choline uptake reached a maximal rate during the first 2 min (Vmax = 0.27 mumol mg-1 protein min-1; Km = 36 microM). Choline uptake during a 30 min incubation was similar to that of single bilayer transport systems described in the literature. Choline incorporation into phosphatidylcholine was saturated above 40 microM external choline concentration (Vmax = 3.7 pmol mg-1 protein min-1; Km = 7 microM). The low rate of choline efflux and the half life of the tissue choline pool (T 1/2 = 3 h), suggests that free choline pools available for efflux in S. mansoni are small. This model allows the determination of whether a proposed effector of membrane phosphatidylcholine synthesis and turnover alters surface bilayer formation through changes in transport of the precursor across the apical surface.     

Renewal of the membrane complex of Schistosoma mansoni is closely associated with lipid metabolism

Metabolic pathways leading to lipid biosynthesis in four different developmental stages of Schistosoma mansoni were explored and quantified by incubation in the presence of labeled precursors in a chemically defined medium. At the schistosomulum stage and in male, female, or paired worms, glycerol and oleate incorporation into neutral lipids, mainly in the form of triacylglycerols, was greater than into phospholipids, whereas in 11-and 15-day-old worms, synthesis mainly led to phospholipids. Incorporation into phospholipids was recovered largely in phosphatidylcholine, and distribution into other phospholipids depended on the developmental stage. Incorporation of choline and ethanolamine into their respective phospholipids represented up to 15% of the parasitic phospholipid content. The formation of phosphatidylcholine by phosphatidylethanolamine methylation occurred mainly in the immature parasitic stages. Inositol incorporation was also measurable, whereas [14C]serine incorporation was low or undetectable. Addition of 1-palmitoyl-2-[14C]oleyl phosphatidylcholine revealed a very high uptake of this phospholipid by the immature stages but further metabolism was not detectable. In contrast, adult S. mansoni were completely unable to take up or absorb this exogenous phospholipid. The most striking aspect of this study was the relatively high metabolic activity in 11-day-old worms and the lower but sustained activity on day 15 and at the schistosomulum stage. By comparison, biosynthetic activity in adult S. mansoni, on which research studies have been focused until now, was very low. We also discuss the participation of lipid metabolism in the constant renewal of the membrane complex which is essential to parasitism by S. mansoni.     

Mitogen effects on lipid metabolism during lymphocyte activation

Mitogenic and non-mitogenic lectins have been compared for their abilities to stimulate acetate and choline incorporation into mouse spleen lymphocyte lipids. The concns required for maximal acetate incorporation correspond to those required for maximal blastogenesis. The non-mitogenic lectins tested had no effect on acetate incorporation. Concanavalin A also stimulated acetate incorporation into splenic lymphocyte lipids of athymic mice which do not undergo T-cell blastogenesis. 4,4′-Diaminodiphenylsulfone (dapsone) at 150μg/ml inhibited the incorporation of choline into mouse spleen lymphocyte phosphatidylcholine by 40%, but had no significant effect on concanavalin A induced mitogenesis when the inhibitor was present during the first few hours of transformation. Enhanced turnover of phospholipids appears to be a parallel but non-essential event in the early stages of mitogenesis.     

Phosphatidylcholine formation is the predominant lipid biosynthetic event in the hemoparasite Babesia bovis

This work examines the lipid composition and metabolism of bovine red blood cells infected by apicomplexan Babesia parasites, organisms closely related to Plasmodium sp. We found that erythrocytes infected with Babesia bovis (i-RBC) accumulate lipids and show striking increases in phosphatidylcholine, phosphatidic acid, diacylglycerol and cholesteryl esters as compared to uninfected erythrocytes cultured under the same conditions (n-RBC). A similar pattern was observed in cultures of erythrocytes infected with Babesia bigemina. The lipid profile of purified B. bovis merozoites showed that phosphatidylcholine is the most abundant phospholipid in this parasite (31.8% +/- 2.8 of total phospholipid), markedly differing from bovine n-RBC, in which it is only a minor component (4.8% +/- 0.6). B. bovis cultures incorporate radiolabeled choline into complex lipids, especially phosphatidylcholine, with minor amounts recovered in sphingomyelin and lysophosphatidylcholine. When [14C] stearate was used as precursor, the labeling pattern again gave the highest incorporation into phosphatidylcholine, with lesser incorporation in sphingomyelin, phosphatidylinositol, phosphatidylethanolamine and phosphatidic acid. Diacylglycerol and small amounts of cholesteryl esters were the only labeled neutral lipids found. B. bovis also incorporates [3H] myo-inositol into phosphatidylinositol. Parallel incubations with n-RBC as a control yielded no incorporation into either polar or neutral lipids with any precursor. These results indicate that the lipid changes observed in i-RBC can be explained on the basis of the lipid biosynthetic activities of the babesial parasite. Gas chromatography-mass spectrometry (GC-MS) analysis of fatty acid methyl esters from phospholipids of i-RBC and n-RBC showed the same qualitative composition in both. However, i-RBC had higher ratios of saturated to unsaturated fatty acids and B. bovis cultures did not desaturate [14C] stearate. Cholesterol was the only sterol detected by GC-MS. Phospholipase A2 treatment of i-RBC and n-RBC revealed no enhanced hemolytic effects in i-RBC, suggesting that the erythrocyte membrane phospholipid composition is essentially unaltered by the parasite. Labeling of i-RBC or n-RBC with [125I] Bolton-Hunter resulted in an enhanced phosphatidylserine labeling in i-RBC. This study provides the first data on B. bovis lipid constitution and biosynthesis. They show that phosphatidylcholine formation is the main biosynthetic process in these cells. The striking differences in the contents of phosphatidylcholine between host erythrocytes and the parasite suggests that it may be a useful target for both chemotherapy and immunoprophylaxis against bovine babesiosis.     

Effect of endurance training on the phospholipid content of skeletal muscles in the rat

Only few data are available on the effect of training on phospholipid metabolism in skeletal muscles. The aim of the present study was to examine the effect of 6 weeks of endurance training on the content of particular phospholipid fractions and on the incorporation of blood-borne [¹⁴C]-palmitic acid into the phospholipids in different skeletal muscles (white and red sections of the gastrocnemius, the soleus and the diaphragm) of the rat. Lipids were extracted from the muscles and separated using thin-layer chromatography into the following fractions: sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, cardiolipin and neutral lipids (this fraction being composed mostly of triacylglycerols). It was found that training did not affect the content of any phospholipid fraction in soleus muscle. It increased the content of sphingomyelin in white gastrocnemius muscle, cardiolipin and phosphatidylethanolamine in red gastrocnemius muscle and phosphatidylinositol in white gastrocnemius muscle and diaphragm. The total phospholipid content in red gastrocnemius muscle of the trained group was higher than in the control group. Training reduced the specific activity of sphingomyelin and cardiolipin in all muscles, phosphatidylcholine in soleus, red, and white gastrocnemius muscles, phosphatidylserine in all muscles, phosphatidylinositol in all except the soleus muscle, and phosphatidylethanolamine in hindleg muscles, but not in the diaphragm compared to the corresponding values in the sedentary group. It was concluded that endurance training affects skeletal muscle phospholipid content and the rate of incorporation of the blood-borne [¹⁴C]-palmitic acid into the phospholipid moieties.     

Age-dependent alterations in lipids and function of rat heart sarcolemma

The objective of the present study was to examine the effect of age on heart sarcolemma structure and function. Sarcolemmal fractions were prepared from hearts of young (1–1.5 months) and adult (10–12 months) rats and assayed for marker enzyme activities. The membrane fractions were found to be devoid of other cellular organelles upon examination by electron microscopy. They were enriched with 5′-nucleotidase and devoid of succinate dehydrogenase activity. The only age-related lipid compositional changes noted in these membranes were changes in the fatty acid composition of membrane phospholipids with increasing age. Most changes were detected in phosphatidylcholine and phosphatidylethanolamine with very little alteration of sphingomyelin and phosphatidylserine plus phosphatidylinositol fatty acids. Polyunsaturated fatty acids, especially 18:2 and 20:4, were decreased with saturated fatty acids increased in membrane phosphatidylcholine and phosphatidylethanolamine fractions as the animal develops. There was a decrease in the specific activities of(Na⁺ + K⁺)-ATPase and 5′-nucleotidase of these membranes with age. On the other hand, membrane (K⁺)-p-nitrophenylphosphatase was not affected by age.     

Breakdown of membrane choline-phospholipids induced by endogenous and exogenous muscarinic agonist is potentiated by VIP in rat submandibular gland

The outflow of tritium from rat submandibular gland fragments, pre-labelled with [³H]choline, following electrical or pharmacological stimulation was studied. Electrical stimulation of the tissue increased the outflow of tritium in a frequency dependent manner. Atropine treatment decreased the electrically-induced release, indicating that the outflow did not reflect acetylcholine from nerve endings, but was largely brought about by postsynaptic receptors. In agreement with this hypothesis, treatment with noradrenaline or carbachol induced a dose dependent increase in tritium outflow from the gland fragments which could be blocked by prazosin or atropine, respectively. Moreover, analysis of the tissue-associated tritium revealed an incorporation primarily in the lipid fraction of the tissue (almost 80%), of which about 90% was in phosphatidylcholine, indicating that this was the source of the tritium outflow. Pre-incubation with vasoactive intestinal polypeptide (VIP), which coexists with acetylcholine in the parasympathetic neurons innervating the submandibular gland, increased the carbachol-induced tritium overflow significantly. The effect of VIP could be imitated by the adenylyl cyclase stimulator forskolin, which increased the carbachol-stimulated tritium efflux in a dose dependent manner. Taken together, our results suggests that muscarinic- and α₁-receptor agonists may activate a phospholipase coupled to phosphatidylcholine hydrolysis in the rat submandibular gland. Endogenous acetylcholine released from parasympathetic nerve endings appear to activate this mechanism. Furthermore, VIP treatment, and the concomitant cAMP-accumulation, potentiates the acetylcholine induced phosphatidylcholine hydrolysis, demonstrating a new type of interaction between the classical transmitter acetylcholine and the co-stored neuropeptide VIP.     

Lipid components of the hydrocarbon assimilating yeast Candida lipolytica (strain 10)

The utilization of n-hexadecane by Candida lipolytica (strain 10) was studied with respect to the lipid content, phospholipid and fatty acid profiles resulting at various growth times. Thin layer chromatography of the lipid extracts showed quantitative changes in the different lipid classes. The phospholipid fraction obtained at each growth time was separated into 8 classes: lysophosphatidylcholine, sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, glycophospholipid, phosphatidylglycerol, cardiolipin, and phosphatidic acid. Differences in the percentage fatty acid composition of the lipid extracts were observed at various stages of growth. The cellular fatty acids included palmitic, palmitoleic (35–52%), stearic, oleic, linoleic (26–39%), and pentadecanoic (2–12%) as major components. This indicates that fatty acid(s) of the same length as that of the substrate was the most abundant component, thus showing intact incorporation mechanism. Fatty acids having longer chain lengths were also formed in substantial amounts indicating C₂ addition and β-oxidation of the fatty acids formed in the yeast.     

In vivo schistosomicidal activity of three novels 8-hydroxyquinoline derivatives against adult and immature worms of Schistosoma mansoni

Schistosomiasis control is widely dependent on a single drug, praziquantel (PZQ). The potential for development of resistance to PZQ has justified the search for new alternative chemotherapies. In a previous study, we have been reported that three of 8-hydroxyquinoline derivatives namely: 3-((8-hydroxyquinolin-5-yl) sulfonyl) pentane-2,4-dione (HQSP), 5-((2,4-diphenyl-3H-benzo[b][1,4]diazepin-3-yl) sulfonyl) quinolin-8-ol (HQBD), and 5-((2,4-diphenyl-3H-pyrido[3,4-b][1,4] diazepin-3-yl) sulfonyl) quinolin-8-ol (HQPD) possess a potent anti-schistosomal activity in vitro. The aim of the present study was to evaluate the in vivo schistosomicidal effect of these three compounds on adult and immature worms of Schistosoma mansoni and their induced pathology. Treatment of S. mansoni-infected mice with 1000, 250, 150, and 200 mg/kg body weight of PZQ, HQSP, HQBD, and HQPD, respectively, reduced adult and immature worm burden by 94.63 and 31.32 %, 73.63 and 5.45 %, 76.5 and 28.11 %, and 81.25 and 56.84 %, respectively, compared to infected untreated mice. Moreover, numbers of egg per gram liver and intestine were decreased by 84 and 95.51 %, 47.84 and 46.28 %, 53.18 and 59.37 %, and 54.22 and 67.26 as a result of PZQ, HQSP, HQBD, and HQPD treatment, respectively. Hepatic granuloma volume was also reduced by 40.10, 42.96, 35.72, and 72.09 % due to PZQ, HQSP, HQBD, and HQPD treatment, respectively. In addition, hepatic histopathological alterations and collagen fiber deposition that accompanied with S. mansoni infection were largely retrieved with different treatments, especially HQPD treatment. Furthermore, humoral immune response, especially IgG response against S. mansoni antigens, was augmented with different treatments. This study concluded that among the three tested 8-hydroxyquinoline derivatives, HQPD is the most effective compound against adult and pre-mature worms of S. mansoni and can be used for the development of a new schistosomicidal drug.     

Schistosomose et géohelminthoses dans le nord-est du Bénin : cas des écoliers des communes de Nikki et de Pèrèrè

Infection with schistosomiasis and soil-transmitted helminthiasis are widespread in sub-Saharan Africa and the burden of disease associated with parasites is enormous. A study was performed to determine the transmission and prevalence of human schistosomiasis and soil-transmitted helminthiasis among school children of Nikki and Perere, two north eastern towns of Benin, bordering Republic of Nigeria. Parasitological investigations by urine filtration and Kato-Katz conducted on 1,344 school children indicated a mean prevalence of S. haematobium and S. mansoni 48.44% and 0%, respectively, in the children of Nikki area and 45.24% and 4.11% in Perere area. Only schoolchildren of Sonon locality were infected by S. mansoni with a mean prevalence rate of 36.24%. KatoKatz tests releaved five species of soil-transmitted helminths: Ankylostoma duodenale (8.16% and 6.73%), Ascaris lumbricoides (6.26% and 2.30%), Enterobius vermicularis (1.09% and 1.97%), Trichuris trichiura (1.97% and 1.90%) and Strongyloides stercoralis (2.04% and 0.99%), respectively, in the schoolchildren of Nikki and Perere areas. The malacological investigations carried out in the freshwater points of each visited locality highlighted the presence of four species of freshwater snails known as intermediate host of schistosome: Biomphalaria pfeifferi, Bulinus forskalii, B. globosus and B. truncatus.Two B. globosus and B. pfeifferi collected in Sonon locality were naturally infected by schistosome, indicated the importance of their two species of snail in schistosome transmission cycle.     

Effect of chlorpromazine on lipid metabolism in aortas from cholesterol-fed rabbits and normal rats, in vitro: Inhibition of sterol esterification and modification of phospholipid synthesis

Chlorpromazine (CPZ), a major tranquilizer, was found to be a potent inhibitor of acylCoA:cholesterol acyltransferase (ACAT, EC 2.3.1.26) in isolated arterial microsomes and in intact arterial tissue from the rat and cholesterol-fed rabbit in vitro. In isolated rabbit arterial microsomes, CPZ resulted in a concentration-dependent inhibition of ACAT with 50% inhibition of [1-¹⁴C]oleoylCoA incorporation into [¹⁴C]cholesteryl esters occurring at 0.1 mM CPZ. CPZ also effectively inhibited the incorporation of [¹⁴C]oleate into triglycerides without affecting incorporation into diglycerides. Additionally, CPZ altered the pattern of arterial phospholipids synthesized from [1-¹⁴C]oleate. Incorporation into phosphatidylcholine was depressed while incorporation into phosphatidylinositol was increased. Since diglyceride synthesis appreared to be unaffected by CPZ, a redirection of phosphatidic acid into the CDP-diglyceride pathway of glycerolipid synthesis does not adequately account for the effect of CPZ on arterial phospholipid and triglyceride synthesis in these experiments.     

Isolation and characterization of hypertrophic type II cells from the lungs of silica-treated rats

Type II cells isolated from the lungs of rats exposed to silica can be separated into two populations by using centrifugal elutriation. One population, designated type IIA, appears similar to type II cells isolated from control lungs. The second population, designated type IIB, consists of type II cells that are larger than type IIA cells or control type II cells. In addition, the type IIB (or hypertrophic) cells contain lamellar bodies which are larger and more numerous than lamellar bodies in type IIA or control type II cells. After centrifugal elutriation, the type II cell populations were purified by differential adherence on rat IgG-coated culture dishes for biochemical and metabolic studies. Type IIB cells contained elevated amounts of protein and total RNA in comparison to type IIA and control type II cells. Type IIB cells contained approximately 2.5-fold more phospholipid than control type II cells (51.5 +/- 3.0 micrograms/10(6) cells versus 20.5 +/- 4.1 micrograms/10(6) cells). Incorporation of the phospholipid precursors [14C]choline and [3H]palmitate into cellular phosphatidylcholines was also increased in type IIB cells. After 120 minutes of incubation, incorporation of [14C]choline into total phosphatidylcholine by type IIB cells was 250% greater than in controls; at this same time point, incorporation of [3H]palmitate was approximately 150% greater than in controls. Incorporation of [14C]choline into disaturated phosphatidylcholine by type IIB cells was 200% greater than in controls. However, no increased incorporation of [3H]-palmitate into disaturated phosphatidylcholine by type IIB cells was seen. These results suggest that the hypertrophic type II cell is responsible for the increases in surfactant-associated phospholipids in the lungs of rats exposed to silica.     

Chronic intestinal nematode infection exacerbates experimental Schistosoma mansoni infection

Mixed-parasite infections are common in many parts of the world, but little is known of the effects of concomitant parasite infections on the immune response or on disease progression. We have investigated the in vivo effects of a chronic gastrointestinal nematode infection on the infectivity and development of the immune response against the common trematode helminth Schistosoma mansoni. The data show that mice carrying an established chronic Trichuris muris infection and coinfected with S. mansoni, had significantly higher S. mansoni worm burdens than mice without coinfection. The increase in S. mansoni worm burden was accompanied by a higher egg burden in the liver. Kinetic analysis of S. mansoni establishment indicate reduced trapping of S. mansoni larvae during skin-to-lung migration, with T. muris-induced alterations in lung cytokine expression and inflammatory foci surrounding lung-stage schistosomula, suggesting that the immunomodulatory effects of chronic T. muris infection elicited at the gut mucosal surface extend to other organs and perhaps specifically to other mucosal surfaces. The data show that a preexisting chronic gastrointestinal nematode infection facilitates the survival and migration of S. mansoni schistosomula to the portal system, and as a result, increases the egg burden and associated pathology of S. mansoni infection.     

Comparative evaluation of Schistosoma mansoni,Schistosoma intercalatum,and Schistosoma haematobium alkaline phosphatase antigenicity by the alkaline phosphatase immunoassay (APIA)

To know if alkaline phosphatase (AP) from schistosomes other than Schistosoma mansoni can be used as diagnostic marker for schistosomiasis in alkaline phosphatase immunocapture assay (APIA), we comparatively tested n-butanol extracts of adult worm membranes from a Venezuelan (JL) strain of S. mansoni (Ven/AWBE/Sm); a Cameroonian (EDEN) strain of Schistosoma intercalatum (Cam/AWBE/Si) and a Yemeni strain of Schistosoma haematobium (Yem/AWBE/Sh). APIA was evaluated with sera of patients from Venezuela, Senegal, and Gabon infected with S. mansoni, from Gabon infected with S. intercalatum or S. haematobium, from Chine infected with Schistosoma japonicum and from Cambodian patients infected with Schistosoma mekongi. Results indicate that 92.5 % (37/40) of Venezuela sera, 75 % (15/20) of Senegal sera, 39.5 % (17/43) of S. haematobium sera, and 19.2 % (5/26) S. intercalatum sera were APIA-positive with the Ven/AWBE/Sm preparation. APIA with the Cam/AWBE/Si preparation showed that 53.8 % of S. intercalatum-positive sera had anti-AP antibodies, and 51.2 %?S. haematobium-positive sera cross-immunocapturing the S. intercalatum AP. APIA performed with Yem/AWBE/Sh showed that 55.8 %?S. haematobium sera were positive. Only two out of nine S. japonicum sera were APIA-positive with the Ven/AWBE/Sm and Cam/AWBE/Si, and no reaction was observed with Cambodian S. mekongi-positive sera. AP activity was shown to be present in all the schistosome species/strains studied. The use of APIA as a tool to explore the APs antigenicity and the presence of Schistosoma sp. infections through the detection of anti-Schistosoma sp. AP antibodies in a host, allowed us to demonstrate the antigenicity of APs of S. mansoni, S. intercalatum, and S. haematobium.     

Dipetalonema viteae infective larvae reach reproductive maturity in rats immunodepressed by prior exposure to Schistosoma mansoni or its products and in congenitally athymic rats

Infective larvae of Dipetalonema viteae did not reach maturity in inbred Fischer rats. However, female adults of D. viteae when transplanted surgically into Fischer rats established and the resulting microfilaraemia from the transplanted worms persisted for about 120 days after infection. Sequential dissections showed that some of the female worms transplanted remained viable in rats for about 35 days after infection. After inoculation of infective larvae into rats a varying number transformed into stage-4 larvae but they did not develop into adult worms and were killed. However, when the rats were immunodepressed non-specifically by a pre-existing Schistosoma mansoni infection or by treatment with S. mansoni-derived substance(s), a number of stage-4 larvae renewed their development and reached sexual maturity. These worms produced microfilariae which were observed in the peripheral blood for about 40 days. The effect of previous infection with S. mansoni on the survival and growth of D. viteae in Fischer rats depends greatly on the relative timing of infection because infective larvae of D. viteae reached maturity only when rats were inoculated with infective larvae after 15 days of S. mansoni infection but not after 21 or 28 days of S. mansoni infection. D. viteae will also develop to maturity in congenitally athymic rats. In congenitally athymic rats (Nu/Nu) each given 75 infective larvae, both the microfilaraemia and adult worm recovery at post-mortem were higher than those which resulted in Nu/Nu rats given an infection of 200 larvae. These experiments show that in rats innate immunity to this filarial nematode reflects a very rapidly induced acquired immunity which kills the parasite before it reaches maturity.