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PubMed2000

A cDNA encoding the highly immunodominant antigen of Strongyloides stercoralis: gamma-subunit of isocitrate dehydrogenase (NAD+).

A full length cDNA encoding the highly immunodominant 41 kDa antigen of Strongyloides stercoralis (P5), recognized by 83% of human patients [Siddiqui et al. (1997) Parasitol Res 83:655-658], is obtained. A clone containing a 1371 bp insert was selected following screening of the S. stercoralis cDNA library with antibodies specific to antigen P5. The nucleotide sequence of this insert identified a cDNA coding for the gamma-subunit of isocitrate dehydrogenase (NAD+), GenBank Accession Number AF176568. The conceptually translated amino acid sequence of the open reading frame for the gamma-subunit of S. stercoralis isocitrate dehydrogenase (NAD+) encodes a 388 amino acid residue protein with an apparent molecular weight of 43 kDa and a predicted pI of 7.15. The sequence is 71% A/T, reflecting the characteristic A/T codon bias of S. stercoralis. The amino acid sequence of the S. stercoralis gamma-subunit of isocitrate dehydrogenase (NAD+) is compared with those of Caenorhabditis elegans, rat and human NAD(+)-ICDH. The diagnostic potential of the S. stercoralis gamma-subunit of isocitrate dehydrogenase (NAD+) is also discussed.

Amino Acid Sequence↗
PubMed1997

Expression of a 70-kDa heat-shock-related protein during transformation from free-living infective larvae to the parasitic stage in Strongyloides venezuelensis.

The in vitro transformation system of Strongyloides venezuelensis has been established which induces free-living infective larvae to transform into the parasitic stage by a temperature shift from 25 to 37 degrees C. Comparison of the profiles of proteins labeled with [35S]-methionine in infective larvae at 25 and 37 degrees C with marked morphological transformation revealed an increase in the 70-kDa protein, thus showing these proteins to be related to the family of heat-shock proteins. In addition, the new appearance of two complexes between 16-kDa and 22-kDa proteins was observed. The 70-kDa protein cross-reacted with monoclonal antibody against human heat-shock protein 70, which was constitutively expressed. These proteins, synthesized during the transformation of S. venezuelensis from the infective larval stage to the parasitic stage, might be crucial for biochemical events that regulate the infectivity of the parasite for the host.

Animals↗
PubMed1997

Strongyloides stercoralis: identification of antigens in natural human infections from endemic areas of the United States.

Using Western-blot analysis, we identified eight immunodominant antigens (apparent molecular weights 96, 86, 75, 56, 41, 32, 28, and 26 kDa) of Strongyloides stercoralis in natural human infections. For this study, 78 individual serum samples were obtained from S. stercoralis-infected patients residing in endemic areas of the United States. Poly A+ RNA was translated in vitro in the rabbit-reticulocyte lysate system. The newly synthesized translation products were immuno-precipitated with S. stercoralis human infection sera. All eight of the identified antigens were detected in the immunoprecipitates. The potential of these antigens as targets for immunodiagnosis is also discussed.

Animals↗
PubMed1999

Strongyloides ratti: additive effect of testosterone implantation and carbon injection on the susceptibility of female mice.

A sex-related difference in host susceptibility to Strongyloides ratti was previously known. Male mice were more susceptible to S. ratti infection and the difference was seen against migrating larvae under the regulation of testosterone. Against migrating larvae, macrophages were assumed to play important roles in host natural immunity. On the basis of these findings, to examine the effect of testosterone on macrophages we treated female mice with testosterone and/or carbon to block the function of macrophages. Mice were then infected with third-stage larvae of S. ratti. By counting of the migrating larvae in the cranial cavity at 36 h after infection the effect of each treatment was assayed. Testosterone treatment alone (Te) or carbon injection alone (Ca) effectively increased the worm recovery. Given together, Te and Ca (Te + Ca) significantly increased the worm recovery to levels almost equal to the sum of those achieved with Te and Ca. The serum testosterone concentration was elevated in mice that had undergone Te and Te + Ca at the time of worm recovery. Surprisingly, the serum testosterone concentration reached after Te + Ca was elevated more than that attained by Te. The same experiment with a half-dose of Te and Ca (Te half + Ca) resulted in the same testosterone concentration achieved with Te and resulted in a worm recovery almost equal to the sum of that achieved with Te and Ca. These results clearly showed that Te and Ca had an additive effect on the recovery of migrating S. ratti larvae. Testosterone had an effect after macrophages had been blocked. The relationship between testosterone and macrophage function during S. ratti infection is discussed.

Animals↗
PubMed2006

Exposure of medical staff to Strongyloides stercolaris from a patient with disseminated strongyloidiasis.

We examined whether medical staff were infected with Strongyloides stercolaris through exposure to the body substances of a patient with disseminated strongyloidiasis. The patient excreted a large number of S. stercolaris organisms in respiratory secretions and stool-like excretions from a nasogastric tube. Blood tests in six physicians and three nurses, who were highly suspected of having had contact with the substances without appropriate protection during medical care of the patient for about 1 week, showed no increase of eosinophiles or IgG antibodies against S. stercolaris. We conclude that adherence to the standard precautions is sufficient for preventing the nosocomial transmission of this organism.

Animals↗
PubMed2006

Optimum methods of inactivation of Strongyloides stercoralis larvae from reclaimed wastewater.

Strongyloidiasis presents a major health hazard when reusing wastewater. Albendazol with a concentration of 4 mg/l, a contact time of 45 min, pH 1.2 and pH 10.2, killed the larva. The larva was also killed with a 0.03% concentration of iodine and a detention time of 30 min or a 0.04% concentration of iodine and a contact time of 10 min. The required detention time to inactivate larva in water was found to be 17 days. The minimum revealed residual chlorine to kill the larvae was 4 mg/l with 120 min of detention time, and a minimum contact time was found to be 80 min with a residual of 23 mg/l. Many methods are available to inactivate the Strongyloides stercoralis, which could be acids, alkaline chemicals, larvicidal chemicals, super chlorination, or just detention time. The best method must be determined according to the prevailing specific environmental site and the feasibility of the selected method(s).

Animals↗
PubMed2005

Coinfection of Schistosoma mansoni and Strongyloides stercoralis in a patient with variceal bleeding.

We report a case of hepatosplenic schistosomiasis with portal hypertension and variceal bleeding in an immigrant patient from Egypt, coinfected with Strongyloides stercoralis. The diagnosis was based on the following: (a) identification of Schistosoma mansoni ova in the stools and colonic biopsy specimens, (b) portal hypertension and esophageal varices with normal liver function and the absence of hepatic cirrhosis stigmata, (c) history of migration from an endemic area and (d) ultrasonographic findings of spleen and liver enlargement, fibrosed portal tracts, and normal lobular architecture of liver parenchyma. Hepatosplenic schistosomiasis should be suspected in any patient from an endemic area who has splenomegaly, portal hypertension, and esophageal varices bleeding in the absence of stigmata of liver cirrhosis and hepatic insufficiency. Coinfection with S. stercoralis could be attributed to common epidemiological features of the parasites and the patient's habits.

Animals↗
PubMed1983

Strongyloides ratti and Trichinella spiralis: net charge of epicuticle.

The intact epicuticles of Strongyloides ratti stage-3 larvae and Trichinella spiralis stage-1 larvae were found to have a surface net negative charge. Ultrastructural studies on S. ratti using cationized ferritin and ruthenium red showed the negative charge to be dense and uniformly distributed over the epicuticular surface. Staining with acetic acid-ferric oxide hydrosol occurred at pH 1.65 and suggests that amino acid carboxyl groups were not responsible for the negative charge property. Alcian blue staining occurred at pH 0.5 and at a critical electrolyte concentration (CEC) of 0.9 M MgCl2, a property similar to that of highly sulfated mucopolysaccharides such as the proteoglycan keratan sulfate. In contrast, T. spiralis larvae failed to stain with alcian blue below pH 5.0 or at a CEC of 0.1 M, suggesting its negative charge is associated with dissociated amino acid carboxyl groups. Attempts to remove the negative charge-bearing components in the epicuticle of S. ratti by detergents, organic solvents, denaturing agents, proteases, uronidases, neuraminidases, and lipases were unsuccessful. The presence of elastin in the S. ratti larval outer cortical layer was indicated by its vulnerability to elastase and its reaction to aldehyde fuchsin-alcian blue stain. These results show that the epicuticle of S. ratti is not a typical cell membrane, although it appears to have ultrastructural similarities. It is suggested that the association of highly sulfated mucopolysaccharides with the epicuticular surface of free-living nematodes such as S. ratti L3 may reflect a greater need to protect against surface desiccation. It is also postulated that the highly negatively charged surface may have anticomplementary and anticoagulation effects.

Animals↗
PubMed1983

Strongyloides ratti: the role of enteral antigenic stimuli by adult worms in the generation of protective immunity in rats.

Immunogenicity of adult Strongyloides ratti was studied in rats. Immunization of rats by intraduodenal implantation of adult worms could completely inhibit the egg production and hasten the expulsion of challenged worms which were developed from subcutaneously inoculated L3 or were implanted intraduodenally as adults. Enteral immunization by intraduodenal implantation of adult worms was, however, not able to affect the esophageal larval output of the challenge infection with L3. In contrast to enteral immunization with adult worms, immunization by full sequence of a primary infection or by a combination of drug-abbreviated infection and adult worm implantation could suppress the esophageal larval output of the challenge infection. The relationship between the host defense mechanism and the life cycle of S. ratti is discussed.

Animals↗
PubMed1984

Strongyloides stercoralis: hyperinfection in immunosuppressed dogs.

Hyperinfective strongyloidiasis involving the threadworm , Strongyloides stercoralis, is well known in humans and primates. Although this nematode also frequently parasitizes dogs, canine hyperinfective strongyloidiasis has not been reported. To determine whether a fulminant pattern of nematode development can occur in dogs, and to test the S. stercoralis/dog system for suitability as a model for human hyperinfective and disseminated strongyloidiasis, five canine infections with a dog-derived strain of S. stercoralis were monitored by the quantitative recovery of larvae from feces. Even 3-month-old pups controlled their initial infections successfully, the number of larvae excreted declining to near zero in 90 days. Immunosuppressive treatment with prednisolone, prednisolone and azathiaprine , or niridazole resulted in a rapid return to former or greater intensities of infection, as judged by larval output. Only first stage ( rhabditiform ) larvae were passed in the feces, although third stage (filariform) larvae occurred in the intestinal contents of dogs when they were examined at necropsy. In 3 of the 5 dogs, the adult worm recovery exceeded the inoculated dose greatly and, in one of these, adults and rhabditiform larvae were found in distant, extraintestinal sites. In the remaining 2 of the 5 dogs, the adult worm population was less than the inoculated dose, but, in both, the infection was terminated by the host's death before hyperinfection could have developed. The observations demonstrate that autoinfection occurs in dogs infected with S. stercoralis and that, if it is allowed to continue for a sufficiently long time in immunosuppressed hosts, massive hyperinfection, and even disseminated infection, may occur. This spectrum of increasingly invasive parasitism closely resembles strongyloidiasis in humans. Therefore, the S. stercoralis/dog system has excellent potential as a model for human hyperinfective and disseminated strongyloidiasis.

Animals↗
PubMed1985

Strongyloides ransomi: proteolytic enzymes from larvae.

The filariform larvae of Strongyloides ransomi can infect their hosts by penetration through skin. In this report, homogenates of these organisms were prepared and their proteolytic enzymes examined. Homogenates prepared in 0.2 M citrate, pH 4.0, contain two thiol-dependent proteinases with molecular weights of approximately 32,000 and 28,000. These proteinases have an acidic pH optimum and show substrate preferences and inhibitor susceptibilities similar to the vertebrate acidic cysteinyl proteinases. Homogenates prepared in 0.1 M Tris, pH 7.5, contain multiple proteolytic enzymes, active against both Azocoll and synthetic substrates. These enzymes do not require thiols for activity and they have an alkaline pH optimum. The enzymes are inhibited by both chelating agents and heavy metals, but not by serine-proteinase inhibitors. Extracts prepared in 0.1 M Tris-HCl, pH 7.5, contain endogenous proteinase inhibitors.

Animals↗
PubMed1987

Strongyloides ratti: formation of protection in rats by excretory/secretory products of adult worms.

Formation of a marked protective immunity against the challenge infection was found in the rats immunized with excretory/secretory (ES) products of Strongyloides ratti adult worms. Immunization by intraduodenal injection of ES products reduced both the fecal egg counts and the adult worm burden by subcutaneous inoculation of infective larvae and by an intraduodenal implantation. The duration of parasitism in the immunized rats, however, was not shortened compared with that of control rats. The normal migration of subcutaneously challenged larvae was not affected by ES product immunization. Intestinal mastocytosis occurred according to the appearance of adult worms in the small intestine of the immunized rats earlier than it did in controls. This result suggests that mastocytosis is involved in the induction of protection by ES products of S. ratti adult worms.

Animals↗
PubMed1989

The acquirement of growth ability for third-stage larvae of Strongyloides ratti during the head-passage in the rat.

The role of larval passage through the head in the course of the migration of Strongyloides ratti in rats was investigated. Third-stage larvae (L3) recovered from various portions of donor rats were re-injected into the skin, cranial cavity and small intestine of recipient rats to check their ability for further growth. Cultured L3 (L3c) and the L3 recovered from the skin of donor rats (L3s) did not survive in the small intestine after intestinal inoculation. However, intestinal inoculation of L3 recovered from the head of donor rats (L3h) revealed growth to the adult stage. Cultured L3 injected into the cranial cavity of rats also became adult worms in the small intestine. L3 incubated in the cranial cavity for more than 24 h could grow in the small intestine of the recipient rats. These experiments suggest that S. ratti L3 acquire their ability to mature in the small intestine during their migration through the head of rats.

Animals↗
PubMed1990

Strongyloides stercoralis: antigenic analysis of infective larvae and adult worms.

The protein composition of Strongyloides stercoralis infective larvae and adult worms solubilized sequentially in water, sodium deoxycholate and sodium dodecyl sulphate (SDS) and their excretory/secretory products were analysed by one- and two-dimensional SDS-polyacrylamide electrophoresis. These extracts were demonstrated to be complex mixtures containing many proteins, some of which were common and others which were stage-specific. Western blot analysis of these antigens with infected human sera showed most sero-reactivity against larval antigens, whilst normal human sera were unreactive. These data identify immunogenic antigens which may be available for detection in an antigen assay.

Animals↗
PubMed1990

Strongyloides venezuelensis infections in mice.

The course and intensity of Strongyloides venezuelensis infection as compared with S. ratti infection were investigated in BALB/c mice. The mice were found to be much more susceptible to infection with S. venezuelensis than S. ratti. The majority of worms inoculated were recovered from the lungs and subsequently from the small intestines, suggesting that their migratory route via the lungs to the small intestine was comparable to that of S. stercoralis in humans. Spontaneous expulsion of worms occurred by about 10 days after infection, which was the same as that of S. ratti. Different infectivities, as assessed by faecal egg excretion, age, sex and strain of mouse were observed in mice infected with S. venezuelensis, as well as in those infected with S. ratti. A striking immunity was acquired following a primary exposure to S. venezuelensis. Mice infected with S. venezuelensis are considered to provide as useful a model as those infected with S. ratti for the study of human strongyloidiasis.

Animals↗
PubMed1990

Effects of spleen cells and serum on transfer of immunity to Strongyloides venezuelensis infection in hypothymic (nude) mice.

The course of Strongyloides venezuelensis infection in congenitally hypothymic (nu/nu) mice and their heterozygous thymus-bearing littermates (nu/+) was followed. Unlike the infected nu/+ mice, the nu/nu mice were unable to expel the worms until the end of the observation period (98 days post-infection). In addition, about three times as many eggs were counted at the peak level of infection in faeces of the infected nu/nu mice in comparison with the nu/+ mice. No acquired resistance to rechallenge was observed among the nu/nu mice. Auto-reinfection within the infected nu/nu mice could not be supposed in the present study. The worm expulsion mechanism was generated by nu/nu mice which had been given syngeneic spleen cells from intact +/+ mice. The expulsion of adult worms, as well as the protection against migrating larvae, occurred anamnestically when spleen cells from immune +/+ mice were transferred. The serum transfer, however, only caused a retardation of larval migration. The results support the hypothesis that direct worm immunity and worm expulsion are a T cell-dependent phenomenon.

Animals↗
PubMed1991

The response of intact Strongyloides ratti infective (L3) larvae to substrates and inhibitors of respiratory electron transport.

Live, intact third-stage larvae (L3s) of Strongyloides ratti in the absence of exogenous substrates consumed oxygen at a rate (E-QO2) of 181.8 +/- 12.4 ng atoms min-1 mg dry weight-1 at 35 degrees C. Respiratory electron transport (RET) Complex I inhibitor rotenone (2 microM) produced 33 +/- 6.5% inhibition of the E-QO2. Unusually the rotenone-induced inhibition was not relieved by 5 mM-succinate. The E-QO2 of intact L3s was refractory to RET Complex III inhibitor antimycin A at 2 microM; 4 microM-antimycin inhibited less than or equal to 10% of the E-QO2. The electron donor couple ascorbate/TMPD augmented the E-QO2 in the presence of rotenone (2 microM) and antimycin A (4 microM) by 110%. Azide (1 mM) stimulated the antimycin A refractory QO2 by 36.6 +/- 7.2% which was only partially inhibited by 1.0 mM-KCN (IC50 = 0.8 mM). The data suggest the presence of classical (CPW) and alternate (APW) electron transport pathways in S. ratti L3s.

Animals↗
PubMed1992

Restoration of the defective natural defence of beige mice against tissue-migrating larvae of Strongyloides ratti by transfer with normal peritoneal cells.

The effects of cell transfer on the defective natural defences of beige (bgj/bgj) mice against Strongyloides ratti were studied by assessing recovery of tissue-migrating larvae from head and lung. Transfer of peritoneal resident cells from normal bgj/+ mice restored the defective natural defence of beige mice. The non-adherent population of normal peritoneal cells did not have the restorative capacity. Macrophages may be important to the natural defence against S. ratti.

Animals↗