bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibabesial effect of the immunomodulator AS101 in mice: role of increased production of nitric oxide
Authors: ROSENBLATT‐BIN H. , KLEIN A. , SREDNI B.
Published: November 2003

The immunomodulator AS101 has been shown to induce cell proliferation and to increase the secretion of a variety of cytokines. In the present study we evaluated the effect of AS101 on the pathogenicity of B. rodhaini infected mice. In order to clarify its mechanism of action we studied the ability of AS101 to activate neutrophils and macrophages, both of which inhibit parasite growth. More specifically, we studied the ability of AS101 to induce secretion of nitric oxide (NO). We found that AS101 protects mice from babesiosis in a time and dose dependent manner. At 10 and 20 μg/injection, two weeks prior to parasites, AS101 significantly increased the number of neutrophils and more than doubled the survival rate of infected mice. Similarly, at these concentrations when injected one month, or at 20 μg, injected 24 h before parasites, AS101 mitigated the course of infection and reduced by half the peak of parasitaemia. At 0.1 μg/ml AS101 induced the secretion of significantly higher levels of NO in vitro than control. This was abrogated by adding the NO synthase inhibitor, NG‐monomethyl‐L‐arginine. In vivo the antiparasitic protection of AS101 was abrogated by another NO synthase inhibitor, aminoguanidine. We found that AS101, partly by elevating levels of NO, can significantly mitigate the course of infection and thus increase survival, and may therefore be proven as an effective antiparasitic drug.
Neutralization of bovine Concanavalin‐A T cell supernatant‐mediated anti‐Cowdria ruminantium activity with antibodies specific to Interferon gamma but not to tumor necrosis factor
Authors: MAHAN S.M. , SILEGHEM M. , SMITH G.E. , BYROM B.
Published: November 2003

In an earlier study we demonstrated that Concanavalin‐A stimulated bovine T cell supernatants inhibited the growth of Cowdria ruminantium in bovine endothelial cells in vitro. An investigation was conducted to identify the cytokines which were responsible for this growth inhibition. Addition of antiserum against bovine interferon gamma (IFNγ) reproducibly neutralized the inhibitory effect of the T cell supernatants, whereas addition of antisera against bovine tumor necrosis factor alpha (TNFα) had no effect. The inhibitory effect of IFNγ on C. ruminantium growth was not mediated by the production of nitric oxide as there was no detectable difference in nitric oxide levels in cultures that were supplemented with T cell supernatants compared with those that were not. The IFNγ mediated anti‐C. ruminantium effect highlights the importance of cell mediated immune responses in control of these infections and in particular incriminates the protective role of T cells, or cells that secrete IFNγ.
The IgG isotypes of specific antibodies in patients with American cutaneous leishmaniasis; relationship to the cell‐mediated immune response
Authors: RODRIGUEZ VESTALIA , CENTENO MARTA , ULRICH MARIAN
Published: November 2003

American cutaneous leishmaniasis (ACL) presents a spectrum of clinical and immunological manifestations. Since the nature of the cellular response appears to play a fundamental role in determining the characteristics of the immunoglobulin isotype of specific antibody responses, we have compared the relative levels of specific antibodies of the four IgG isotypes against Leishmania in sera from patients with different clinical manifestations of ACL. Using a specific antibody capture assay, significant levels of antibodies of the IgG1, 2 and 3 isotypes were detected in localized cutaneous leishmaniasis (LCL); the average level of IgG4 antibodies was low and they were not detected in 10/20 sera. Sera from muco‐cutaneous leishmaniasis (MCL) gave a comparatively strong IgG1 response. Sera from diffuse cutaneous leishmaniasis (DCL), the rare form characterized by antigen‐specific anergy of cell‐mediated immunity, showed highly significant levels of IgG4 antibodies compared to antibody levels of this isotype in the other groups; IgG1 and IgG2 levels were also elevated. Based on other studies of the relationship between the IgG isotype response and cell‐mediated immunity, these results confirm a Th1‐like CD4+ T cell response in LCL and MCL and a significant Th2‐like response in DCL.
Protection of rats against malaria by a transplanted immune spleen
Authors: FAVILA‐CASTILLO LUIS , MONROY‐OSTRIA AMALIA , KOBAYASHI EIJI , HIRUNPETCHARA T CHAKRIT , KAMADA NAOSHI , GOOD MICHAEL F.
Published: November 2003

A number of reports have suggested that the spleen plays a key role in the regulation of immunity to malaria but the role, if any, of other tissues is less clear. Furthermore, numerous functional changes occur in the spleen following malaria infection and it is not known whether the spleen’s role relates primarily to its content of malaria‐specific lymphocytes or to the altered structure and function that has occurred. To address these issues we have generated splenic chimeras by transplanting spleens between Plasmodium berghei‐immune and naive rats. In the absence of a functional spleen, specific immune responses from both isolated splenic and non‐splenic cells can partially control infection. However, an immune spleen in a naive rat can solidly protect the animal from malaria and a normal spleen in an otherwise immune rat can provide enhanced protection over the non‐splenic state. Thus, in the presence of functional splenic architecture both splenic and non‐splenic malaria‐specific lymphocytes operate more effectively. However, these studies do demonstrate an important role for non‐splenic tissue in immunity at least for P. berghei in the rat. The study could have important implications for induction of protective immune responses by vaccination and suggests that malaria‐specific lymphocyte responses induced in the periphery following vaccination could interact with parasites in both spleen‐dependent and spleen‐independent ways.
Kinetics of nitric oxide production during infection and reinfection of mice with Plasmodium chabaudi
Authors: TAYLOR‐ROBINSON ANDREW W. , SEVERN ALISON , PHILLIPS R.STEPHEN
Published: November 2003

We have shown previously that at the time of peak primary parasitaemia of P. chabaudi infection in NIH mice, significant levels of nitric oxide are produced, detectable as nitrate in the serum, and that these contribute to the protective immune response to infection. Here, we demonstrate that following reinfection, mice show a markedly diminished ability to produce nitrate. However, if mice are treated with L‐NG‐monomethyl arginine specifically to block nitric oxide metabolism during the primary infection, and are then reinfected, production of nitrate is restored to levels approaching those attained at peak primary parasitaemia. These experiments, together with others we have reported, indicate that whereas nitric oxide appears to play a significant role in control of the primary parasitaemia of P. chabaudi infection, it performs no such function during subsequent patent parasitaemias. Furthermore, they suggest that factors as yet unknown may regulate nitric oxide activity during malaria infection, such that under normal circumstances its production comes under strict control. This is exemplified by the observation that after the burst of nitric oxide activity that coincides with peak primary parasitaemia, there follows a prolonged period of immunological tolerance during which nitrate levels remain low even at secondary challenge infection. This tolerized state is lifted only several months after initial infection, when the nitric oxide activity at reinfection appears to correlate with the size of the parasite challenge and the presence of a patent parasitaemia. The implications of these findings for protective immunity to malaria, malarial immunosuppression, and immunoregulation in general, are discussed.
Increased frequency of HLA‐DR3 and complotype SCO1 in Mexican mestizo children with amoebic abscess of the liver
Authors: ARELLANO JORGE , PÉREZ‐RODRÍGUEZ MARTHA , LÓPEZ‐OSUNA MARTHA , VELÁZQUEZ JUAN R. , GRANADOS JULIO , JUSTINIANI NANCY , SANTOS JOSÉ IGNACIO , MADRAZO ARMANDO , MUÑOZ LINDA , KRETSCHMER ROBERTO
Published: November 2003

The increase of HLA‐DR3 and complotype SCO1 previously found in Mexican mestizo adults with E. histolytica amoebic abscess of the liver, was also found in Mexican mestizo children of either sex with the same disease, when compared to the healthy control population (adults and/or children) of the same ethnic and socioeconomic background. This HLA and complotype pattern was not found in Mexican Mestizo patients with amoebic rectocolitis. No linkage disequilibrium was found between these and the other MHC determinants tested in this survey. Thus, HLA‐DR3 and SCO1 may constitute primary, independent risk factors, not for any kind of amoebic tissue invasion (i.e. amoebic rectocolitis), but specifically for amoebic liver abscess, irrespective of age or sex. The possibility of linkage disequilibrium with other factors (i.e. the TNF family) within or close to the MHC that were not tested in this study, is discussed. Children with amoebic liver abscess revealed a significant increase in HLA‐DR5, and the absence of HLA‐DR6 when compared to adults with amoebic liver abscess, suggesting that at least in this ethnic group these class II HLA traits may contribute to some of the peculiarities of pediatric amoebic liver abscess as opposed to the adult version of this disease. HLA‐DR3, SCO1, but also HLA‐DR5 and HLA‐DR6 have all been associated with certain forms of immune‐dysfunction, and may thus contribute to some of the clinical and immunological features of this parasitic disease.
Presence of antibodies in the aqueous humour and cerebrospinal fluid during Leishmania infections in dogs. Pathological features at the central nervous system
Authors: Garcia‐Alonso M. , Nieto C.G. , Blanco A. , Requena J.M. , Alonso C. , Navarrete I.
Published: November 2003

In the present paper we show that in dogs, naturally infected with Leishmania infantum, the aqueous humour and the cerebrospinal fluid contain anti‐Leishmania IgGs and that the specificity of antigen recognition of these fluids is similar to that of the sera. We also show that in the encephalon and cerebellum of these dogs there is a pathological sponge‐like reaction accompanied by neuronal degeneration, mobilization of glial cells together with accumulation of amyloid deposits. The interstitial and intravascular deposition of IgGs and Leishmania antigens in choroid plexus suggest that in these animals there is a failure of the blood‐cerebrospinal and ciliary bodies filtration barriers which may allow the transfer of anti‐Leishmania IgGs from the blood stream to these fluids. We suggest that the failure of the blood‐cerebrospinal barrier and the in situ concentration of anti‐Leishmania IgGs and antigens in brain tissues may predispose to the pathological features detected in this compartment.
Carbohydrates on the surface of Echinococcus granulosus protoscoleces are immunodominant in mice
Authors: MÍGUEZ MARINA , BAZ ADRIANA , NIETO ALBERTO
Published: November 2003

A carbohydrate enriched soluble fraction (CHP) was prepared by mild treatment of viable Echinococcus granulosus protoscoleces (PSC) with the enzyme endoglycosidase‐F (endo‐F) and characterized by SDS‐PAGE, glycoside‐ inhibition ELISA, and immunoblotting. Three groups of four BALB/c mice were immunized with the CHP, with the remaining deglycosylated PSC (DGP) and with dead PSC (DPSC) to analyse the relative immunogenicity of carbohydrates on the surface of PSC. A fourth sentinel group was not immunized. The antibody response was analyzed during primary and hyperimmune responses. Specific antibody titres (IgG and IgM) against somatic PSC antigens (PSA) were evaluated by ELISA and their antigen recognition pattern by immunoblotting, discriminating carbohydrate and peptide specific antibody responses by periodate treatment of PSA. The avidity index of those antibodies and the titer of non‐specific immunoglobulins during the whole protocol were evaluated by ELISA. In vitro mitogenic activity of CHP was also evaluated. The results indicated: 1) immunodominance of surface carbohydrate epitopes from PSC, 2) predominant IgM and low avidity response against these epitopes, 3) a dramatic increase of non‐specific antibody titres and 4) in vitro mitogenic activity of CHP.
The flagellar fraction of Trypanosoma cruzi depleted of an immunosuppressive antigen enhances protection to infection and elicits spontaneous T cell responses
Authors: HANSEN DIANA S. , ALIEVI GUSTAVO , SEGURA ELSA L. , CARLOMAGNO MIRTA , MOREIN BROR , VILLACRES‐ERIKSSON MARIA
Published: November 2003

The flagellar fraction (FF) of Trypanosoma cruzi can be separated by immunoaffinity chromatography in two fractions with balanced but opposite immunological effects. The immunoaffinity purified fraction has immunosuppressive activity mediated at least partially by TGF‐β (Hansen et al., submitted). Here we report that the fraction depleted of immunosuppresive antigens (FT) administered with iscom‐matrix as adjuvant provides enhanced protection to an infection challenge in immunized mice. In vitro, the FT but not the FF stimulated resident peritoneal cells to produce IL‐1 and IL‐6. In immunized mice, the FT elicited higher levels of antigen‐specific IgG2a than the FF as well as broader recognition of T. cruzi antigens. Splenocytes from mice immunized with FT proliferated spontaneously in vitro and secreted TH1 and TH2 cytokines. The protection provided by FT correlates with its capacity to enhance the secretion of IFN‐γ. We postulate that immunosuppressive antigens present in the FF prevent the development of memory cells secreting IFN‐γ through a TGF‐β dependent mechanism.
Brugia pahangi in cats: the passive transfer of anti‐microfilarial immunity from immune to non‐immune cats
Authors: MEDEIROS FILOMENA , BALDWIN C.I. , DENHAM D.A.
Published: November 2003

Serum from cats (Felis catus) that were repeatedly infected with Brugia pahangi and had become amicrofilaraemic (mf‐ve) was injected intravenously into microfilaraemic (mf + ve) cats. If more than 1 μl of immune serum per 1000 mf was injected, microfilarial counts fell dramatically within minutes and, in some cats, mf completely disappeared. In most cases mf reappeared 21–44 days later. However, in two experiments mf never reappeared and circulating antigen (indicative of the presence of living adults) could not be detected. At autopsy no adult worms were found, but in one cat 6 mf/ml were detected by filtration of cardiac blood. Passive transfer of single Ig isotypes showed that IgG is the immunoglobulin responsible for the mf killing effect of immune serum, and that IgGl is probably the most active isotype. Mf killing and destruction, occurred in the lungs in an antibody dependent cell mediated reaction involving neutrophils, eosinophils and mononuclear cells. Three of the 20 recipient cats died from what appeared to be anaphylactic shock while under anaesthesia probably due to the sudden release of inflammatory mediators in the lung.
Synergistic action of cyclosporin A and polyspecific rabbit anti‐sera against murine Schistosoma mansoni
Authors: MILLERSHIP J.J. , CHAPPELL L.H. , FALLON P.G.
Published: November 2003

The efficacy of cyclosporin A (CsA) treatment against Schistosoma mansoni in mice was compared with treatments that included co‐administration of one of two anti‐sera (infected rabbit serum (IRS) obtained by repeated infection and a worm membrane antigen anti‐serum (WSS) obtained by immunization with worm surface supernatants). These two sera recognized a number of worm antigens but differed in precise detail. Administration of CsA alone to mice harbouring mature infections of S. mansoni reduced worm burdens and preferentially targeted female worms. Sera administered alone had no effect on worm burdens. Co‐administration of worm membrane antigen anti‐serum (WSS) with CsA reduced worm burden significantly compared with drug treatment alone. Male worms were more susceptible to this combined treatment regime. Anti‐infection serum (IRS) had a lesser stimulatory activity in combination with CsA which was not statistically different from the effects of CsA alone on worm burdens. The data suggest that CsA‐induced surface damage to the parasite may reveal specific antigens that were previously unavailable for host attack.
The tegument of Schistosoma mansoni: functional and immunological features
Authors: ABATH FREDERICO G.C. , WERKHAUSER ROBERTO C.
Published: November 2003

Some structural, biophysical and molecular features of the tegument are shown, highlighting their changes during maturation as important adaptative mechanisms for the survival of the parasite and resistance to immune attack. On the other hand, many antigens, targets of the immune response against the schistosome, are located on the tegument. Some of the features of these molecules are presented and the possibilities of using them in the immunological control of the disease are discussed.
GM‐CSF‐induced priming of human neutrophils for enhanced phagocytosis and killing of asexual blood stages of Plasmodium falciparum: synergistic effects of GM‐CSF and TNF
Authors: KUMARATILAKE LAKSHMI M. , FERRANTE ANTONIO , JAEGER TIMOTHY , RZEPCZYK CHRISTINE
Published: November 2003

Granulocyte macrophage‐colony stimulation factor (GM‐CSF), which is a haematopoietic cytokine generated by activated T lymphocytes and macrophages during infection, was investigated for its effects on human neutrophil‐mediated killing of asexual blood forms of Plasmodium falciparum. Pretreatment of neutrophils with human recombinant‐GM‐CSF markedly increased the parasite killing (measured by a radiometric assay), in the presence of normal serum (containing complement), immune serum (IS), purified IgG (from IS) or heat inactivated IS. GM‐CSF pretreatment also enhanced phagocytosis of the parasite by neutrophils and the expression of CR3, FcγRII and FcγRIII receptors. Treatment of neutrophils with a combination of GM‐CSF and TNF resulted in a synergistic increase in phagocytosis and killing of the parasite. The findings suggest that GM‐CSF is likely to form part of the cytokine network responsible for regulating the antiparasitic activity of the neutrophil in malaria.
Sm480: a high molecular weight Schistosoma mansoni antigen associated with protective immunity
Authors: CURTIS ROSANE H.C. , FALLON PADRAIC G. , DOENHOFF MICHAEL J.
Published: November 2003

Rabbit antisera were raised against an antigen present in Schistosoma mansoni adult worms and eggs, and were shown to yield a single immunoprecipitin arc in immunoelectrophoresis and immunodiffusion against S. mansoni egg and worm antigen extracts. The antisera conferred partial but significant protection (22–30%) against a S.  mansoni challenge when transferred to mice five and six days after the mice had been infected percutaneously with 200 cercariae. The egg and the worm forms of the antigen were immunologically cross‐reactive, but the egg antigen possessed peptidolytic activity that could be inhibited with serine protease inhibitors. In indirect immunofluorescence the rabbit antisera reacted with surfaces of cercariae, five‐day old lung‐stage schistosomula, miracidia and praziquantel‐treated adult worms. Gel‐filtration chromatography demonstrated a relative molecular size of approximately 480 kDa for both the egg and worm forms of the antigen, and lectin‐affinity chromatography indicated both were glycosylated. The serine protease activity and large relative molecular size of egg Sm480 were confirmed by a combination of radiolabelling with tritiated di‐isopropyl fluorophosphate, immunoelectrophoresis and polyacrylamide gel electrophoresis.
Revisiting host/parasite interactions: molecular analysis of parasites collected during longitudinal and cross‐sectional surveys in humans
Authors: MERCEREAU‐PUIJALON ODILE
Published: November 2003

This paper summarizes the first conclusions arising from an analysis of parasite diversity in blood samples collected during longitudinal surveys conducted in Senegal. Parasite typing was carried out using a PCR‐based molecular analysis of allelic polymorphism. The parasite populations circulating in the village of Dielmo during periods of intense transmission (when the inoculation rate was 0.5–1 infective bite/night) are characterized by a considerable allelic diversity of the MSP‐1, MSP‐2 and TRAP loci. A large proportion of blood samples contained several MSP‐1 or MSP‐2 alleles. In asymptomatic carriers, the complexity of the infections (number of alleles and genetic diversity of these alleles) was age‐dependent. In children, the trend was for a reduced complexity during clinical episodes. Molecular typing showed that successive clinical episodes experienced by children were caused by genetically distinct parasites. Longitudinal analysis of asymptomatic carriers indicated that in the absence of transmission, the same parasite types were carried for long periods, while rapidly changing profiles were observed during intense transmission season. The consequences of these findings on our understanding of acquired anti‐parasite immunity in humans living in endemic are discussed.
Protective immunity induced by vaccination with Onchocerca volvulus tropomyosin in rodents
Authors: TAYLOR MARK J , JENKINS ROSALIND E. , BIANCO ALBERT E.
Published: November 2003

A cDNA clone of Onchocerca volvulus, designated MOv14, and encoding 136 amino‐acid residues from the C‐terminus of O. volvulus tropomyosin, was evaluated as a protective immunogen in two complimentary rodent models of onchocerciasis. Vaccination of BALB/c mice with the recombinant fusion of MOv14 coupled to Maltose‐Binding Protein (MBP) induced significant reductions (48–62%) in the recovery of Onchocerca lienalis microfilariae from the skin, compared to control groups immunized with MBP alone. The predominant antibody response generated to MOv14 by vaccination was of IgG1. Following a similar vaccination protocol in Mongolian jirds, two independent experiments demonstrated that 16 weeks after infection with Acanthocheilonemaviteae there was a 46% reduction in the recovery of adult worms in vaccinated animals compared to control groups. Antibodies generated by vaccination recognized a product released during culture of A. viteae infective larvae which migrated at a distinct molecular mass from native tropomyosin from somatic tissues.
Evidence for direct interaction between mast cells and Leishmania parasites
Authors: BIDRI MOHAMED , VOULDOUKIS IOANNIS , MOSSALAYI M. DJAVAD , DEBRÉ PATRICE , GUILLOSSON JEAN‐JACQUES , MAZIER DOMINIQUE , AROCK MICHEL
Published: November 2003

When stimulated through IgE‐ (or IgG‐) immune complexes with parasite antigens, mast cells can release several cytokines, including IL‐4, IL‐6, IL‐10, IL‐12, Interferon‐γ (IFN‐γ) and tumour necrosis factor‐α (TNF‐α) that may influence the host response to Leishmania major in modulating lesion size and persistence during experimental infection in the mouse. Moreover, recent data demonstrated that mast cells are able to be antibody‐independently activated by direct contact with bacteria, making them important elements in innate immunity. Given these data, we asked whether cell‐parasite contact could directly induce mast cell mediator release and whether mast cells could be infected by L. major or L. infantum parasites. In this study, we showed that a pure homogeneous population of mouse bone marrow derived mast cells (BMMC) in contact with living L. major or L. infantum promastigotes, but not with attenuated parasites or soluble parasite antigens, released preformed mediators such as β‐hexosaminidase and the preformed pool of TNF‐α within minutes. Furthermore, direct cell‐parasite contact induced TNF‐α synthesis by mast cells within hours. Moreover, we demonstrated by in vitro co‐culture experiments that metacyclic L. major or L. infantum promastigotes are directly infective for a significant proportion of BMMC and are transformed into intracellular amastigotes. Taken together, these data suggest that mast cell can participate in the first line of defence, i.e. innate immunity, during local cutaneous infection with Leishmania parasites.
Intradermal immunization of rats with plasmid DNA encoding Schistosoma mansoni 28 kDa glutathione S‐transferase
Authors: DUPRÉ LOÏC , POULAIN‐GODEFROY ODILE , BAN ELISABETH , IVANOFF NATHALIE , MEKRANFAR MOHAMED , SCHACHT ANNE‐MARIE , CAPRON ANDRÉ , RIVEAU GILLES
Published: November 2003

Direct administration of plasmid DNA encoding an antigen represents an attractive approach to vaccination against infectious diseases, particularly in developing countries where easy‐to‐handle and cost‐effective vaccines are needed. We have investigated the potential of DNA immunization to induce a specific antibody response against Schistosoma mansoni, using plasmid‐DNA encoding the protective antigen, S. mansoni 28 kDa glutathione S‐transferase (Sm28GST). Since S. mansoni parasite penetrates into its host through the skin, this tissue was chosen for plasmid DNA delivery. Following plasmid DNA administration into the skin of rats, the parasite antigen was detected in skin cells by immunohistochemistry. Three administrations of 200 μg plasmid at 14 day intervals led to the induction of a long‐lasting specific IgG antibody response in the sera of immunized rats, with a predominance of IgG2a and IgG2b subclasses. Sera of immunized animals were able to mediate antibody‐dependent cellular cytotoxicity in vitro, leading to the specific killing of parasite larvae. A parasite challenge performed on plasmid DNA‐immunized animals induced a strong and rapid boosting effect on the specific IgG antibody response. These results demonstrate the potential of genetic immunization via the skin with plasmid DNA encoding Sm28GST for inducing immune responses with protective patterns against an S. mansoni infection.
Production of IgE antibodies against the 22 kDa tegumental membrane‐associated antigen of schistosomes is directed by the antigen itself
Authors: WAINE G.J. , MAZZER D.R. , McMANUS D.P.
Published: November 2003

It has previously been reported that the predominant target of immunoglobulin E (IgE) recognition in sera from humans infected with Schistosoma japonicum in The Philippines or with S. mansoni in Kenya, is a 22 kDa tegumental membrane‐associated schistosome antigen. In the present study, we demonstrate that the 22 kDa antigen can direct the production of antigen‐specific IgE antibodies independently of schistosome infection and in the absence of any other parasite components or adjuvant. Three strains of mice were immunized using the purified, recombinant 22 kDa antigen of S. japonicum without the use of any adjuvant. Sera from all three strains of immunized mice, but not control animals, generated IgE antibodies specific for the native 22 kDa schistosome antigen in Western blots. Thus, the 22 kDa antigen itself must contain signals (presumably encoded by the primary amino acid sequence or by the secondary or tertiary structures of the molecule, or by a combination of these) which are sufficient to direct the isotype switch required for production of antigen‐specific IgE.
Antibody response of Echinococcus granulosus infected mice: Protoscolex specific response during infection is associated with decreasing specific IgG1/IgG3 ratio as well as decreasing avidity
Authors: SEVERI Ma.ANGELICA , FERRAGUT GABRIELA , NIETO ALBERTO
Published: November 2003

The antibody response was followed during 68 weeks in 17 Balb/c mice intraperitoneally (i.p.) infected with Echinococcus granulosus protoscoleces (PSC) and in three mice i.p. immunized with dead PSC. Titres of antibodies recognizing peptidic and glucidic PSC epitopes, as well as their isotypic and avidity profiles were followed by ELISA. In addition, antigen recognition patterns were analysed by immunoblot. The response against carbohydrate epitopes was dominant in infected and immunized mice but stronger in the first group. Infected mice showed similar profiles of specific IgG and IgM with maximum titres from week 38 to 53. Although IgG1 and IgG3 were the predominant antibody subclasses, the ratio of IgG1/IgG3 antibody titres as well as antibody avidity decreased during the experiment, encompassing a decrease in recognition of peptidic epitopes. Immunized mice did not show significant levels of specific IgM and, after week 15, showed IgG titres lower than the infected mice. IgG1 was the predominant IgG subclass during all the experiment with background levels of IgG3. The mean Ab avidity was high and showed no significant changes during immunization. Different patterns of response were thus produced by dead and developing live parasites. Although high avidity IgG1 antibodies were early found in both cases, lower avidity IgG3 antibodies were increasingly produced afterwards only in infected animals. The isotype switch and avidity decrease observed only during infection are consistent with a possible parasitic mechanism to evade host immunity.
The isolation of a 22 kDa band after SDS‐PAGE of Schistosoma mansoni adult worms and its use to demonstrate that IgE responses against the antigen(s) it contains are associated with human resistance to reinfection
Authors: DUNNE D.W. , WEBSTER M. , SMITH P. , LANGLEY J.G. , RICHARDSON B.A. , FULFORD A.J.C. , BUTTERWORTH A.E. , STURROCK R.F. , KARIUKI H.C. , OUMA J.H.
Published: November 2003

In schistosomiasis endemic areas, intensities of reinfection after treatment are greater amongst young children than amongst adults, and high levels of parasite‐specific IgE are associated with resistance to reinfection in an age‐dependent manner. Previously we have reported that, in Western blots, a 22 kDa band was recognized by human IgE and that the incidence and intensity of S. mansoni reinfection were significantly lower amongst individuals who had IgE against this band, compared with those who did not (Dunne et al. 1992). Here we report the isolation of a 22 kDa SDS‐PAGE band, its incorporation into ELISA and the demonstration that levels of human anti‐22 kDa IgE had a significant negative correlation with intensities of subsequent reinfection. Rabbit anti‐22 kDa band serum recognized the outer tegument, gut tegument, and the collecting ducts and flame cells of adult worms. The 22 kDa band antigen(s) was also present in ‘lung’‐ and ‘post‐lung’ schistosomula stages of S. mansoni, and in S. haematobium, S. bovis and S. japonicum adult worms. Metabolic labelling of schistosomula and worms demonstrated the in vitro synthesis and release of 22 kDa antigens.
Antibodies to diethylcarbamazine potentiate the antifilarial activity of the drug
Authors: MUKHOPADHYAY S. , RAVINDRAN B.
Published: November 2003

The antifilarial drug diethylcarbamazine citrate (DEC) is known to mediate in vivo microfilaricidal activity in conjunction with the host immune system. In this study passive transfer of antibodies to DEC elicited by immunization with methyl piperazine carboxylic acid (MPCA) coupled to bovine serum albumin (BSA), was found to potentiate microfilaricidal activity of subcurative doses of DEC in Setaria digitata infected Mastomys coucha. Active immunization of microfilaraemic animals with MPCA‐BSA followed by administration of subcurative doses of DEC also resulted in rapid clearance of microfilaraemia in both S. digitata and Brugia malayi infected M. coucha indicating the synergistic activity of DEC and the antibodies to the drug. Since some of the filarial antibodies are known to react with DEC, it is proposed that such antibodies may potentiate the microfilaricidal activity of the drug in vivo.
Sequential nucleic acid and recombinant adenovirus vaccination induces host‐protective immune responses against Taenia ovis infection in sheep
Authors: ROTHEL J.S. , BOYLE D.B. , BOTH G.W. , PYE A.D. , WATERKEYN J.G. , WOOD P.R. , LIGHTOWLERS M.W.
Published: November 2003

Sheep were immunized with a protective recombinant antigen (45W) from the cestode parasite Taenia ovis using three different vaccine delivery systems, either alone or in different combinations. The DNA encoding 45W was cloned into the expression plasmid pcDNA 3 and an ovine adenovirus to create nucleic acid and recombinant viral vector vaccines, respectively. Sheep received two vaccinations with various combinations of these two delivery systems and/or purified recombinant 45W protein in a conventional vaccine formulation containing Quil A as adjuvant (protein/Quil A vaccine). Sheep receiving two inoculations of either the nucleic acid or the recombinant adenovirus alone, demonstrated only low levels of 45W‐specific antibody. However, immunization with either nucleic acid or recombinant adenovirus primed animals to mount an enhanced immune response after a subsequent vaccination with the protein/Quil A vaccine. The most striking result was that sheep initially immunized with the nucleic acid vaccine and boosted with the recombinant adenovirus, mounted IgG1 responses >65 fold higher than those of sheep receiving either vaccine alone. The level of antibody in these sheep was commensurate with that observed in animals vaccinated twice with the protein/Quil A adjuvanted vaccine. In both cases, host‐protection from experimental challenge infection with T. ovis was obtained.
Heterogeneity in the recognition of Ostertagia circumcincta antigens by serum antibody from mature, infected sheep
Authors: McCRIRIE L. , BAIRDEN K. , BRITTON C. , BUITKAMP J. , McKEAND J.B. , STEAR M.J.
Published: November 2003

The recognition of parasite molecules from third‐stage and adult Ostertagia circumcincta by serum antibody was studied in a group of matched, mature Scottish Blackface sheep that had been naturally and then deliberately infected. A total of 20 molecules was recognized in somatic extracts from third‐stage larvae and 31 molecules in somatic extracts from adult parasites. However, no sheep recognized all immunogenic molecules and no molecule was recognized by all sheep. There was no obvious relationship between recognition of any parasite antigen and polymorphism at class I loci or at the DRB1 class II locus of the major histocompatibility complex in these outbred animals. Only 15 molecules from third‐stage larvae were present at a frequency suitable for statistical analysis and recognition of three of these 15 molecules was associated with differences in worm burdens. Recognition of two of five molecules from adult parasites was associated with differences in worm length. These results indicate that variation in the recognition of specific, identifiable parasite molecules may be partly responsible for variation among sheep in resistance to O. circumcincta
A comparison of humoral responses to Schistosoma haematobium in areas with low and high levels of infection
Authors: MUTAPI F. , NDHLOVU P.D. , HAGAN P. , WOOLHOUSE M.E.J.
Published: November 2003

Antibody responses to Schistosoma haematobium of 280 Zimbabweans were studied in two areas of differing infection levels. 133 of the subjects came from a low infection area with a prevalence of 33.8% and geometric mean infection intensity of 0.8 eggs per 10 ml of urine, while 147 of the subjects came from a high infection area with a prevalence of 62.7% and geometric mean intensity of 3.2 eggs per 10 ml of urine. Both the age‐prevalence and age‐intensity curves exhibited a peak shift. IgA, IgE, IgG, IgG1, IgG2, IgG3, IgG4, and IgM antibody levels against soluble egg antigen (SEA) and whole worm homogenate (WWH) were assayed by ELISA. Females produced significantly more anti‐SEA IgG1, IgG4, IgM, anti‐WWH IgE and IgG1. People from the high infection area produced significantly more anti‐SEA IgE, IgG3 and anti‐WWH IgG3 and significantly lower levels of anti‐SEA IgA, IgM and anti‐WWH IgM when the effects of infection intensity, sex and age had been allowed for. The age profiles of anti‐SEA IgA, IgG and anti‐WWH IgA and IgM reflected current levels of infection while anti‐WWH IgG1, IgG2 and anti‐SEA IgG1 evolved more slowly with age, and anti‐WWH IgE rose with age in both areas. Some antibody responses, anti‐SEA/WWH IgM, anti‐SEA IgG1 and possibly anti‐SEA/WWH IgA showed different age profiles in the two areas, with changes in antibody levels occurring at a younger age in the high infection area suggesting that immune responses are evolving more rapidly in residents of this area. This result clearly demonstrates that antibody levels are not a function of age alone.
Excretory/secretory products from plerocercoids of Spirometra erinacei reduce iNOS and chemokine mRNA levels in peritoneal macrophages stimulated with cytokines and/or LPS
Authors: FUKUMOTO SOJI , HIRAI KAZUMITSU , TANIHATA TAKEO , OHMORI YOSHIHIRO , STUEHR DENNIS J. , HAMILTON THOMAS A.
Published: November 2003

During infection with plerocercoids of Spirometra erinacei, organisms in the peritoneal cavity of infected animals have many bound inflammatory leukocytes yet survive apparently unharmed. Coculture of IFNγ and LPS stimulated mouse peritoneal macrophages with live plerocercoids suppressed the mRNA expression of the inducible isoform of nitric oxide synthase (iNOS) and JE, the murine homologue of monocyte chemotactic protein‐1 (MCP‐1). Excretory/secretory (ES) products from plerocercoids also suppressed the induced iNOS and JE mRNA and reduced nitrite production of macrophages in a dose dependent manner. The suppression of inducible mRNA levels in macrophages cultured for 24 h with ES products varied with the nature of the stimuli; IFNγ/LPS‐induced iNOS mRNA levels were effected less than were iNOS mRNA levels induced by IFNγ/IL‐2 or IFNγ/TNFα. Similar findings were obtained when nitrite production was measured. Thus modulation of LPS and cytokine inducible mRNA levels appear to be the primary target of ES products. We speculate that a major physiological role for this inhibitory activity in ES products might be the down regulation of pro‐inflammatory gene expression.
IL‐10 deficit correlates with chronic, hypersplenomegaly syndrome in male CBA/J mice infected with Schistosoma mansoni
Authors: BOSSHARDT STEPHEN C. , FREEMAN JR. GEORGE L. , EVAN SECOR W. , COLLEY DANIEL G.
Published: November 2003

Twenty weeks after moderate level infections with Schistosoma mansoni, approximately 20% of male CBA/J mice develop hypersplenomegaly syndrome (HSS) while the rest present with moderate splenomegaly syndrome (MSS). HSS and MSS mice differ pathophysiologically (degree of splenomegaly, anaemia, ascites, periportal fibrosis, portal hypertension) and immunologically with regard to antibodies (idiotypic expression, isotype levels) to schistosome soluble egg antigens (SEA), and spleen cell phenotypic profiles. This study compared in vitro proliferative responses and IL‐2, IFNγ, IL‐4, and IL‐10 production by spleen cells from uninfected mice and mice with acute (8 wk), MSS or HSS schistosomiasis mansoni, upon exposure to anti‐CD3ε or SEA. Spleen cells from uninfected mice produce IL‐2 to anti‐CD3ε, but exposure of cells from all three groups of infected mice to anti‐CD3ε or SEA led to only very low levels of supernatant IL‐2. Anti‐CD3ε‐ or SEA‐stimulated production of IFNγ or IL‐4, and anti‐CD3ε‐stimulated production of IL‐10, displayed similar patterns: highest cytokine production by cells from mice with acute infections and lower levels of production that did not differ between the two chronic groups. In contrast, while SEA‐stimulated IL‐10 production was again highest with cells from mice with acute infections, spleen cells from mice with MSS produced significantly more IL‐10 than did those from mice with HSS. This association of low levels of antigen‐induced IL‐10 with severe pathology is consistent with the theory that IL‐10 plays a role in the immunoregulation that occurs in chronic schistosomiasis.
A dominant B‐cell epitope on the 22 kDa tegumental membrane‐associated antigen of Schistosoma japonicum maps to an EF‐hand calcium binding domain
Authors: WAINE G.J. , MAZZER D.R. , BRANDT E.R. , McMANUS D.P.
Published: November 2003

The 22 kDA tegumental surface membrane‐associated antigen of schistosomes is of recognized importance in immunity to schistosomiasis. Here, we have defined linear B‐cell epitopes on the recently cloned and expressed recombinant Schistosoma japonicum 22 kDa antigen (reSj22), using mice immunized with this molecule. Sera from three strains of mice, CBA, C57BL/6 and BALB/c, representing different genetic backgrounds, were reacted with a series of overlapping synthetic peptides in epitope‐scanning studies. The predicted hydrophilic N‐terminal domain was found to be highly immunogenic, containing several sequences that were strongly recognized by all strains of mice. The most dominant epitope identified, corresponding to peptide 6, was located in a region previously identified as an EF‐hand calcium binding domain. In contrast, the more hydrophobic C‐terminal region of the molecule was poorly recognized, with the exception of a single peptide encoding residues 121–140 that was recognized by CBA and C57BL/6 but not BALB/c mice, suggesting that the latter epitope was genetically restricted between the strains. The data presented here describing the epitope mapping of this molecule may prove important in research aimed at further defining immune responses to schistosomal antigens.
Phytochrome chromophore‐deficient mutants
Authors: TERRY M. J.
Published: November 2003

Phytochrome chromophore‐deficient mutants have been used as phytochrome‐deficient plants to study many aspects of plant development. However, there are still a number of important questions to be resolved concerning both the targets and the phenotypic consequences of these mutations. Recently, progress has been made in our understanding of the molecular basis of the chromophore deficiency in these mutants. Biochemical assays for the committed steps of chromophore synthesis have been developed and used to demonstrate that the pcd1 and yellow‐green‐2 mutants of pea and tomato, respectively, are unable to synthesize biliverdin IXα from heme while pcd2 and aurea are deficient in phytochromobilin synthase activity. This review focuses on how this information can be used to help understand the basis of other chromophore‐deficient mutants, such as the hy1 and hy2 mutants of Arabidopsis, and discusses how the phenotype of chromophore‐deficient mutants is related to lesions in the chromophore biosynthesis pathway.
Chromophore: apoprotein interactions in phytochrome A*
Authors: SONG P.‐S. , PARK M. H. , FURUYA M.
Published: November 2003

Phytochromes are molecular light switches by virtue of their photochromic red/far‐red reversibility. The His‐324 residue next to the chromophore‐linked Cys‐323 plays a critical role in conferring photochromism to the tetrapyrrole chromophore in native phytochrome A. The chromophore appears to be enclosed between the amphiphilic α‐helical chains in a hydrophobic pocket. The absorbance maxima of both the Pr and the Pfr forms of pea phytochrome A are blue‐shifted by 10 and 20 nm, respectively, upon C‐terminal truncation. We speculate that the quaternary structure of the phytochrome A molecule involves some interactions of the C‐terminal half with the chromophore domain. The Pfr conformation of phytochrome includes an amphiphilic α‐helix of the amino terminal chain, which occurs in 113 ms after picosecond photoisomerization of the Pr form. Compared to α‐helical folding, unfolding of the α‐helix occurs faster in about 310 μs upon phototransformation of the Pfr form of phytochrome A. The photochromic transformation of phytochrome A modulates protein kinase‐catalysed phosphorylation sites in vivo and in vitro, but only a subtle local change in conformation is detectable in the phosphorylated phytochromes. This suggests that the post‐translational modification serves as a surface label, rather than a transducer‐activating trigger, for the recognition of a putative phytochrome receptor.
Regulation of flowering by photoperiod in Arabidopsis
Authors: COUPLAND G.
Published: November 2003

The flowering time of Arabidopsis thaliana is strongly influenced by light quality and photoperiod length. Broadly, two classes of mutations have been characterized that disrupt the response to photoperiod. The first of these, which includes early flowering 3 (elf3), probably influences flowering time by affecting the endogenous cir‐cadian rhythm that enables the duration of the photoperiod to be measured. The genes affected by the second class of mutations, which includes constans (co), are required to promote flowering in response to long photoperiods. The CONSTANS gene has been cloned, and analysis of transgenic plants in which the gene is expressed from a strong viral promoter indicates that transcriptional regulation of CO is an important determinant of flowering time in response to photoperiod. I describe recent progress in understanding these two classes of mutations, and how they influence flowering time in response to photoperiod.
The role of COP1 in light control of Arabidopsis seedling development
Authors: TORII K. U. , DENG X. W.
Published: November 2003

The Arabidopsis seedling can follow two contrasting developmental programmes, photomorphogenesis in light and skotomorphogenesis in darkness. CONSTITUTIVE PHOTOMORPHOGENIC I (COP1) is an essential regulatory gene required for repression of seedling photomorphogenic development in darkness. Recent mutational and overexpression analyses of the COP1 gene suggest a central role for COP1 in light control of seedling development and point to functional implications of its structural domains. Cell biological studies of COP1 have provided a clue to how light regulates the repressive activity of COP1 and thus seedling development.
The role of mutants in the search for the photoreceptor for phototropism in higher plants
Authors: BRIGGS W. R. , LISCUM E.
Published: November 2003

Early attempts to identify the chromophore of the photoreceptor for phototropism are reviewed. Carotenoids and flavins were the principal candidates, but studies with grass coleoptiles devoid of carotenoids suggest that at least in these organs carotenoids are most unlikely to play that role. The status of characterization of a gene for a putative photoreceptor protein is also reviewed. As the action spectrum for phototropism resembles the absorption spectrum of a flavoprotein, flavoproteins are attractive candidates at present, especially since the CRY1 photoreceptor in Arabidopsis thaliana that mediates blue light‐dependent hypocotyl growth suppression has flavin adenine dinucleotide as one of its two chromophores. As the second chromophore appears to be pterin, pterins should not be ruled out as candidate chromophores for the photoreceptor for phototropism.
The phytochrome gene family in tomato (Solarium lycopersicum L.)
Authors: PRATT L. H. , CORDONNIER‐PRATT M.‐M. , KELMENSON P. M. , LAZAROVA G. I. , KUBOTA T. , ALBA R. M.
Published: November 2003

Phytochrome apoproteins in angiosperms are encoded by a small gene family. Tomato (Solatium lycopersicum L.) serves well as a dicotyledonous model system for elucidating the extent of this gene family, its expression patterns, and the roles of individual members of the family. Five phytochrome genes (PHYA, PHYB1, PHYB2, PHYE and PHYF have been characterized in tomato. Quantitative measurements of transcript abundances from each tomato PHY throughout the life cycle indicate that transcript levels generally range from 10 to 100 μmol mol−1 total mRNA, in the following order of decreasing abundance: PHYA, PHYB1, PHYE, PHYB2 and PHYF. PHYA transcripts were found to be most abundant in seedling roots, while PHYB2 and PHYF transcripts were expressed preferentially in fruit. PHYA mutants (fri) have been found to be the consequence of a single nucleotide substitution adjacent to the 3′ terminus of an intron. What are almost certainly PHYB1 mutants have also been described, although the molecular nature of these mutants remains to be revealed. Efforts to obtain PHYB2, PHYE and PHYF mutants are currently underway.