bluuebunny/crossref_metadata_2025 huggingface dataset:
Post lung‐stage schistosomula of Schistosoma mansoni exhibit transient susceptibility to macrophage‐mediated cytotoxicity in vitro that may relate to late phase killing in vivo
Authors: PEARCE EDWARD J. , JAMES STEPHANIE L.
Published: October 2007

Summary Studies of protective immunity against Schistosoma mansoni in immunized mice suggest that a proportion of challenge parasites may be eliminated after they have passed through the lungs of the host several days after infection; however, no potential immune effector mechanism of resistance against this stage of the parasite has yet been identified, since schistosomes have been shown to rapidly become resistant to antibody–dependent killing mechanisms. In this study, different development stages of S. mansoni were examined for their susceptibility to in vitro cytotoxicity by lymphokine–activated macrophages. As previously shown, newly transformed larvae were readily killed by lymphokine–treated peritoneal macrophages or the macrophage cell line IC‐21 (80 % mortality over 48 h in vitro), whereas 7 and 10 day old lung–stage parasites had become refractory to macrophage effects. However, after 2 to 2 1/2 weeks of development in vivo, juvenile parasites recovered from the liver were again susceptible to activated macrophage‐mediated cytotoxicity (25–65 % mortality). Ultrastructural studies of 2 1/2 week old parasites co–cultured with activated IC‐21 cells revealed that damage was largely restricted to the areas beneath the parasite surface and gut syncitia; surface membrane disruption was not evident. This late stage of suceptibility was transient and by 4 to 6 weeks liver–stage worms had again become refractory to macrophage killing. The interaction of post lung–stage parasites with activated macrophages was antibody independent. Furthermore, schistosomes isolated from the portal circulation 2 1/2 weeks after infection showed no evidence of surface‐bound immunoglobulin in a quantitative immunofluorescence assay, nor did antisera from chronically infected mice (CIS) or mice vaccinated with irradiated cercariae (VS) react with the surface of these parasites in vitro, making the possibility of direct antibody–dependent killing mechanisms unlikely. However, both CIS and VS did recognize excretory/secretory proteins synthesized by 21/2 week old liver‐stage schistosomes, including a major antigen of approximate Mr (x 10‐‐3) 220 (220K). It is therefore possible that such antigens might participate in protective immunity, for example via immune complex formation or activation of sensitized T cells. These observations support the role of macrophages as immune effector cells in mice immunized against Schistosoma mansoni, and provide the first physiologically relevant mechanism whereby the immune system might recognize and kill post‐lung stage schistosomes.
Cellular mechanisms involved in recovery from acute malaria in Gambian children
Authors: BROWN JIM , GREENWOOD BRIAN M. , TERRY ROLAND J.
Published: October 2007

Summary This paper reports the results of in vitro experiments which attempt to elucidate the mechanisms whereby Gambian children control acute infections of Plasmodium falciparum. It was shown initially that mononuclear cells from children with acute malaria, in the presence of specific antibody, caused a marked reduction in in vitro parasite growth. IgM antibodies appeared to be considerably more effective than IgG. T or B lymphocytes were ineffective in the system; adherent cells alone had some effect, but much less than the unfractionated cell population. Adherent cells were however fully effective after exposure to supernatants from T cells activated either non‐specifically by phytohaemaggluti‐nin (PHA), or specifically by P. falciparum antigens. Depression of parasite growth was also observed, independent of anti‐malarial antibody. This was achieved when adherent cells from healthy Europeans, as well as those from infected children, were exposed to the supernatants from previously stimulated T cells before adding to the culture. Furthermore, intra‐erythrocytic parasite death occurred after a short exposure to the supernatants of ‘activated’ adherent cells from both infected children and Europeans.
Bovine helper T‐cell clones specific for lymphocytes infected withTheileria parva(Muguga)
Authors: BALDWIN C. L. , GODDEERIS B. M. , MORRISON W. I.
Published: October 2007

SummaryT‐cell clones specific for lymphocytes infected withTheileria parvawere derived from animals immunized by infection withT. parva(Muguga). These clones were non‐cytolytic and had the BoT4+BoT8‐surface phenotype, BoT4 and BoT8 being the bovine analogues of human CD4 and CD8 molecules. The clones proliferated in response to irradiated autologous lymphoblasts infected withT. parva(Muguga) but not to autologous uninfected lymphoblasts or monocytes. They were parasite strain‐specific, in that they did not respond to autologous lymphoblasts infected with another parasite stock,T. parva(Marikebuni). The clones proliferated in the absence of exogenous T‐cell growth factor (TCGF) and produced TCGF when stimulated with concanavalin A. Induction of proliferation of the cloned T‐cells was genetically restricted, and evidence was obtained which indicated that they were restricted by determinants on class II major histocompatibility complex (MHC) molecules. These findings demonstrate that infections withT. parvastimulate antigen‐specific MHC‐restricted T‐cells with the properties of T‐helper cells. The results also provide further evidence for the expression of a parasite strain‐specific antigen on the surface ofT. parva‐infected lymphocytes.
Induction of protective immunity against Schistosoma mansoni by a non‐living vaccine. V. Effects of varying the immunization and infection schedule and site
Authors: JAMES S. L.
Published: October 2007

Summary Intradermal (i.d.) injection with non‐living schistosome antigens plus bacterial adjuvant protects mice against subsequent infection with Schistosoma mansoni. This protection became apparent within 2 weeks after a single inoculation and persisted for at least 8 weeks. Administration of one or more booster immunizations enhanced the level of protection but never produced complete resistance to cercarial challenge under the conditions tested. All immunized mice recognized the Sm 97 antigen in adult worms, as measured by antibody reactivity in ELISA, although the level of reactivity did not correlate with the level of resistance. Significant protection was observed when mice were immunized in the skin of the chest, the footpad or at the base of the tail if challenge infection was administered percutaneously either on the abdomen or back. However, when mice were infected by cercarial exposure of the tail skin, the level of resistance was consistently lower regardless of the immunization site. Vaccinated mice were not resistant to infection with lung stage parasites. These results demonstrate that the i.d. vaccine induces significant and persistent resistance in mice, the level of which is strengthened by booster immunization. The resistance is unrelated to inflammation at the site of immunization. However, immune response at the challenge site may play a critical role in the effector mechanism of resistance in this model.
Systemic release of a mast cell proteinase following nematode infections in sheep
Authors: HUNTLEY J. F. , GIBSON S. , BROWN D. , SMITH W. D. , JACKSON F. , MILLER H. R. P.
Published: October 2007

Summary An enzyme‐linked immunosorbent assay (ELISA) for sheep mast cell proteinase (SMCP) has been developed. Concentrations of SMCP in homogenates of abomasal tissue from parasite‐immune sheep (341 μg SMCP/g tissues) were raised when compared to those in normal (non‐infected) abomasa (0±145 μg SMCP/g tissue). SMCP was not detected in sera from normal animals challenged with Haemonchus contortus but was present 1±4 ng SMCP/ml) was detected in lymph from 2/3 and 4/5 immune animals between 1 and 4 days post‐challenge with 50000 larvae, but not from normal animals. SMCP was not detected in lymph from immune animals following challenge with 1000 Ostertagia larvae. The relatively low concentrations of SMCP in blood and lymph reflect the presence of proteinase inhibitor(s) which interfered with the ELISA.
Two‐dimensional electrophoretic comparison of the antigens and biosynthetically labelled proteins of Trichostrongylus colubriformis and Ostertagia circumcincta
Authors: MILNER A. R. , BEALL J. A. , ORWAT A.
Published: October 2007

Summary The proteins and antigens of different life stages of Trichostrongylus colubriformis were compared with those of Ostertagia circumcincta in an attempt to identify the subset of parasite molecules that is genus‐specific and that may therefore be involved in the induction of genus‐specific, host‐protective immunity. Novel short‐term culture techniques were instituted to label biosynthetically the proteins of the infective larval and adult stages of the parasites using 35S‐methionine. High resolution, two‐dimensional electrophoretic profiles of the labelled proteins indicated that the majority of proteins synthesized by adults were also present in the larval stages. Qualitative differences in the levels of these common proteins were observed, indicating differences in protein expression or turnover. There was extensive homology between larvae from the different species, with only eight major differences apparent in their profiles of biosynthetically‐labelled proteins. Western blot analysis using immune sheep sera indicated that extensive homology also existed between the antigens of T. colubriformis and O. circumcincta larvae.
Variable expression of the murine natural resistance gene Lsh in different macrophage populations infected in vitro with Leishmania donovani
Authors: CROCKER PAUL R. , DAVIES ERYL V. , BLACKWELL JENEFER M.
Published: October 2007

Summary Various macrophage populations isolated from mice (including congenic C57BL/10ScSn and B10.LLshr) bearing resistant or susceptible alleles for the natural resistance gene (Lsh) were infected with Leishmania donovani amastigotes in vitro and examined (a) for their ability to support growth of the amastigote population over 7 days of culture in vitro, and (b) for their ability to express Lsh gene controlled resistance and susceptibility in vitro. Resident macrophages from liver (Kupffer cells), spleen and lung, as well as 7‐day bone marrow‐derived macrophages and bone marrow macrophages obtained after 6 weeks of continuous culture in vitro, all supported growth of the amastigote population. Of these, significant differences in amastigote numbers in macrophages from Lshs and Lshr mice were observed after 48 h of infection in vitro for liver, lung and 7‐day bone marrow macrophage populations only. Resident peritoneal macrophages grown in adherent or suspension cultures neither supported growth of the amastigote population nor showed any evidence of Lsh gene expression in vitro. Hence, multiplication of the parasite appeared to be a necessary but not sufficient condition for observation of Lsh gene activity against L. donovani in vitro. Use of tritiated thymidine incorporation and autoradiography to label dividing amastigotes showed equivalent multiplication of the parasite in liver macrophages from Lshs and Lshr mice between 24 h and 48 h after infection in vitro, with a dramatic difference observed thereafter. This was consistent with earlier observations of a 2–3 day delay in expression of Lsh gene controlled resistance in vivo. Comparison with studies using Salmonella typhimurium and Mycobacterium bovis suggests that the gene may be restricted in its action to a particular point in the parasite cell cycle, perhaps at the level of regulating DNA replication.
Topography of epitopes on a polymorphic schizont antigen of Plasmodium falciparum determined by the binding of monoclonal antibodies in a two‐site radioimmunoassay
Authors: WILSON CHRISTINA F. , ANAND RITA , CLARK JOHN T. , MCBRIDE JANA S.
Published: October 2007

Summary The topographic distribution of common and variant epitopes on two divergent allelic forms of the 185–205K schizont glycoprotein of Plasmodium falciparum were studied by a two‐site radioimmunoassay using monoclonal antibodies. Similarities in the conformation of the two molecules were apparent. On both antigens two distinct regions were mapped, each comprising of both strain‐common and polymorphic epitopes. Epitopes common to the two PSAs were found to be closely associated with different variable epitopes in tertiary structure. It is suggested that this may contribute to parasite evasion of the host immune response.
Protective immunity to malaria: studies with cloned lines of Plasmodium chabaudi chabaudi in CBA/Ca mice. III. Protective and suppressive responses induced by immunization with purified antigens
Authors: BATES M.D. , NEWBOLD C.I. , JARRA W. , BROWN K.N.
Published: October 2007

Summary The protective effect of affinity purified antigen has been investigated in an experimental model for malaria which shows a well marked recrudescence of parasitaemia, a feature of the disease in man. A monoclonal antibody (MoAb) recognizing an epitope common to two genetically distinct cloned lines of Plasmodium chabaudi (AS and CB). was used to purify a Mr250 000 polymorphic schizont antigen (PSA) from these parasites. The purified preparations were then examined for the presence of specific and cross‐reactive epitopes by immunoprecipilation with a panel of MoAb raised against P. chabaudi AS. When tested previously on smears of parasitized blood by immunofluorescence, or against lysates of parasitized erythrocytes by immunoprecipitation, most of these MoAb had been found to be AS specific. When either AS or CB affinity purified Mr 250 000 PSA was used as the target, these same MoAb immunoprecipitated both antigens, and in some cases, a number of associated polypeptides (AP) which co‐purify with the Mr 250 000 PSA. Subsequently, mice were immunized with either the purified AS or CB antigens in Freund's complete adjuvant (FCA). Pre‐challenge sera were compared by indirect immunofluorescence and immunoprecipitation. Sera from mice immunized with AS antigen reacted strongly with AS and cross‐reacted with CB parasite preparations. Pre‐challenge serum from CB antigen immunized mice reacted well with CB, but only faintly with AS preparations. In mice immunized with the AS antigen and then challenged with either AS or CB parasites, the initial parasitaemias were delayed in appearance and the height of the peak parasitaemia reduced, an effect which was most pronounced after challenge with homologous parasites. Only homologous challenge of the mice immunized with CB antigen produced statistically significant modification of the initial parasitaemia. In the immunized mice challenged with homologous parasites, the delayed appearance and slightly reduced peak of the primary parasitaemia was associated with delayed resolution of the patent parasitaemia and significant enhancement of the recrudescence.
Evidence for a neutrophil‐mediated protective response in malaria
Authors: NNALUE NDUBISI A. , FRIEDMAN M.J.
Published: October 2007

Summary Zymosan‐activated and non‐activated human polymorphonuclear neutrophils (PMN) were added to in‐vitro cultures of the human malaria parasite Plasmodium falciparum in microtitre wells. Microscopic counting of parasites in Giemsa‐stained smears showed that at a PMN:RBC ratio of 1:150, the same as occurs in human malaria, parasites in wells with zymosan‐activatcd neutrophils were suppressed 65%. Determination of parasite nucleic acid synthesis by 3H‐hypoxanthine incorporation showed that in wells with PMN:RBC ratio of 1:150 parasite viability was only 22% of control. Various oxygen scavengers were tested for ability to reverse the effects of activated neutrophils on parasite development. Superoxide dismutase (20 mg/ml) and catalase (50 mg/ml) had no effect; tryptophan protected the parasites to a moderate degree while histidine alleviated suppression of parasite development to the greatest extent. This suggests that singlet oxygen is the most effective neutrophil product in killing or suppressing the growth of parasites. We also observed that non‐activated neutrophils were activated by parasites and/or their products resulting in killing of newly‐released parasites.
Cytotoxic activity of rat granulocytes against Mesocestoides corti
Authors: COOK R.M. , ASHWORTH R.F. , CHERNIN J.
Published: October 2007

Summary Rat eosinophils or neutrophils were purified from peritoneal washings which had been enriched cither for eosinophils by infection with the parasite Mesocestoides corti or by intravenous injection with Sephadex G200 particles, or for neutrophils by the intraperitoneal injection of glycogen. Neither eosinophils nor neutrophils attached to or damaged live M. corti parasites in vitro although they did lyse chick erythrocytes in the presence of rat anti‐chick red blood cell antibody, with the neutrophils showing the highest level of cytotoxicity and the eosinophils from the infected rats the lowest. Neutrophils gave a specific antibody‐dependent cytotoxic response to chick erythrocytes coated with solubilized M. corti extract, a response not seen with eosinophils. The cytotoxicity shown by neutrophils could not be blocked by adding eosinophils or sera obtained from chronically infected rats although it was reduced by incubating the neutrophils with cell‐free supernatants obtained from the spleen cells of infected rats following stimulation with solubilized parasite extract in vitro. Eosinophils from infected rats expressed fewer membrane Fc receptors for antibody than did neutrophils or eosinophils from uninfected animals. Incubation of neutrophils and eosinophils from uninfected rats with the immune spleen cell supernatants reduced Fc receptor expression to levels similar to those seen with eosinophils from infected animals. These same supernatants had no effect on the expression of granulocyte complement receptors. It is suggested that infection of rats with M. corti can lead to the production of an antigen‐specific suppression capable of impairing the antibody‐dependent activity of granulocytes in vitro.
A comparative study of infections with rodent isolates of Giardia duodenalis in inbred strains of rats and mice and in hypothymic nude rats
Authors: SHARMA AGNES WAIGHT , MAYRHOFER GRAHAM
Published: October 2007

Summary Giardia isolated from mice and rats have been identified as Giardia duodenalis by morphological criteria. No differences in the eleclrophorctic mobilities of 28 enzymes were detected between the mouse and rat isolates or between these isolates and human and cat isolates. Infections with both rodent isolates have been studied in several strains of inbred rats. No significant differences were detected between the rat strains, with the mouse isolate producing a self‐limiting infection and the rat isolate a chronic infection. After the primary infection was eradicated with metronidazolc, all strains of rats were resistant to reinfection with the homologous isolate. Both isolates produced chronic infections in hypothymic nude rats. BALB/c mice were found to be relatively resistant to primary infection with either isolate but C3H mice became infected chronically with the mouse isolate and experienced a prolonged infection with the rat isolate. These findings resemble those observed with infections with G. muris in the same strains of mice (Roberts‐Thomson & Mitchell 1978). It is suggested that infections with G. duodenalis in rats may offer a model for giardiasis that is based on organisms related closely to G. lamblia. Comparative studies using the two rodent isolates may lead to a belter understanding of how the parasite establishes as a chronic infection and which antigens induce protective immune responses.
In‐vivo encapsulation and killing of Litomosoides carinii in white rats
Authors: OGBOGU V.C. , STOREY D.M.
Published: October 2007

Summary Ultrastructural studies revealed that in albino rats Litomosoides carinii was encapsulated and eventually killed in the pleural cavity by adherent host cells. Encapsulation was an organized cellular reaction which sequestered and eventually degraded the parasites. The process evolved in three phases: primary accumulation of host cells, especially eosinophils and macrophages, around the parasites with concentration of eosinophils on the parasite surface; secondary transformation of macrophages into epithclioid cells which replaced eosinophils on the parasite surface; finally, dead parasites became calcified and were gradually degraded within a tough, compacted fibrotic capsule.
The effect of MHC compatibility between parasite–infected cell line and recipient in immunization against tropical theileriosis
Authors: INNES E. A. , OUHELLI H. , OLIVER R. A. , SIMPSON S. P. , BROWN C. G. D. , SPOONER R. L.
Published: October 2007

Summary Lymphoblastoid cell lines, infected and transformed in vitro by a Moroccan stock of Theileria annulata, infected and immunized susceptible taurine cattle, at cell doses of 108, 106, 104 and 102, regardless of whether the recipients were Bo LA matched or mismatched to the donor cell line. The MHC relationship between the cell line and recipient did affect the severity of the clinical response to cell line immunization which may reflect differences in the specific priming of the immune response. At the highest cell doses the BoLA–mismatched recipients reacted more severely than the BoLA–matched. This study shows that, unlike the closely related parasite T. parva, there is no histocompatibility barrier to immunization using T. annulata–infected cell lines which could be achieved with as few as 102 allogeneic infected cells. The role of MHC compatibility between cell line and recipient in the priming of a protective immune response is discussed.
Killing of Plasmodium falciparum by human monocyte–derived macrophages
Authors: JONES K. REBECCA , COTTRELL BARRIE J. , TARGETT GEOFFREY A. T. , PLAYFAIR JOHN H. L.
Published: October 2007

Summary Freshly isolated human peripheral blood monocytes inhibited the growth of blood–stage asexual Plasmodium falciparum parasites in vitro. The monocytes contained intracellular parasite pigment and a few whole parasites, but the remaining parasites reinvaded fresh red cells successfully and were morphologically normal. Anti–parasitic activity of these macrophages was not significantly enhanced by treatment with recombinant tumour necrosis factor α, recombinant γ–interferon or lymphoblastoid a–interferon. Catalase had no effect on this parasite inhibition, suggesting a hydrogen peroxide independent mechanism. Anti–parasitic activity was, however, enhanced by prior maturation of the monocytes. Monocytes matured for 6 days caused 100% killing of parasites. In contrast to identical concentrations of freshly isolated monocytes the parasites incubated with these matured macrophages showed intraerythrocytic death similar to the crisis forms seen in vivo, γ–interferon present either during the assay or as a pretreatment had no significant enhancing effect on the killing, although cytotoxicity to tumour cell lines was enhanced. Conditioned medium from macrophages showed only moderate parasite inhibition.
Larval membrane antigens protect Hereford cattle against infestation with Boophilus microplus
Authors: WONG J.Y.M. , OPDEBEECK J.P.
Published: October 2007

Summary Hereford cattle (Bos taurus) were immunized with antigens solubilized with Triton X‐100 from larval membranes of the cattle tick (Boophilus microplus). Based on tick egg production compared to control cattle, vaccinated cattle were protected (78%) against challenge with 2 × 20000 tick larvae. The soluble Triton X‐100 extract of tick larval membranes was further purified by immunoaffinity chromatography, using immunoglobulin ligands (IgG1 and IgG2) from three immune steers, previously vaccinated with membrane antigens from the midgut of partly engorged adult female ticks. Cattle vaccinated with these purified antigens were protected in two separate experiments (80 and 89% respectively), against challenge with 2 × 20000 larval ticks compared to control cattle. Whole larval membranes used as vaccines in cattle reduced the amount of eggs produced from ticks by 47% compared to control cattle, but this difference was not significant.
Sixty‐six kilodalton‐related antigens of Plasmodium knowlesi are merozoite surface antigens associated with the apical prominence
Authors: THOMAS A.W. , BANNISTER L.H. , WATERS A.P.
Published: October 2007

Summary We have previously reported that Fab fragments of a monoclonal antibody to the 66 kD‐related antigens of Plasmodium knowlesi inhibit merozoite invasion of erythrocytes, strongly suggesting a role for these antigens as merozoite receptors for red cells. In this paper we have examined the distribution of these antigens on the surface of free merozoites. Rapid immunofluorescence microscopy on free, unfixed cells demonstrated a preferential association of antigen with a polar region of merozoites. This was confirmed, and localized essentially to the apical region, by immunoelectron microscopy under a variety of fixation regimes. Metabolic inhibitors did not affect the distribution, suggesting that apical localization is not due to capping induced by cross‐linking antibodies. These observations suggest that 66 kD‐related antigens may play a role in the orientation of the apical prominence of merozoites towards the red cell, and/or in the junction formation that occurs subsequent to orientation.
Synthesis and secretion of immunoglobulin by spleen cells from resistant and susceptible mice infected with Trypanosoma brucei brucei GUTat 3.1
Authors: NEWSON JANET , MAHAN SUMAN M. , BLACK SAMUEL J.
Published: October 2007

Summary By 6 days after infection of susceptible C3H/He and resistant C57BL/6 mice with Trypanosoma brucei brucei GUTat 3.1, splenic plasma cell responses of both strains of mice were similar in terms of plasma cell number, intracellular Ig, Ig secretion, Ig class and Ig specificity for surface‐accessible variant surface glycoprotein (VSG) epitopes on the infecting organisms, despite higher parasitae‐mia in the C3H/He mice. By 7 days after infection, however, although splenic plasma cells from both strains of mice had greatly amplified their Ig responses, those from C57BL/6 mice (which cleared parasites from their bloodstream between 6 and 7 days after infection) contained and secreted 3–5 times more Ig specific for exposed VSG epitopes on the infecting organisms than those from C3H/He mice which did not clear parasites from their bloodstream. In vitro, trypanosomes can absorb significant amounts of VSG‐specific antibody produced by splenic plasma cells. However, differences in the detection of VSG‐specific antibodies present in, and secreted by, splenic plasma cells of 7‐day infected C3H/ He and C57BL/6 mice were shown not to result from the presence of parasites in the cultures of C3H/He spleen cells. It is argued that between 6 and 7 days after infection, the C3H/He mice selectively lose the capacity to support development of plasma cells specific for exposed VSG epitopes on the infecting organisms and that this is a consequence rather than a cause of differences in the peak levels of first wave parasitaemia.
Characterization of a family of monoclonal antibodies which bind Schistosoma japonicum egg antigens and express an interstrain cross‐reactive idiotype
Authors: OLDS G. RICHARD , KRESINA THOMAS F.
Published: October 2007

Summary A family of monoclonal antibodies (MoAb) was derived from the somatic cell fusion of P3NS1 myeloma cells and lymphoid cells from naturally infected mice or hyperimmunized mice. C57BL/6 mice were naturally infected with Schistosoma japonicum, and BALB/c mice were hyperimmunized with preparations of S. japonicum soluble egg antigens (SEA). The MoAbs which reflected the immune repertoire of naturally infected animals versus hyperimmune animals were characterized with regard to antibody isotype, antigen binding specificity, in‐vitro immunosuppression of antigen‐induced cell‐mediated immune responses and the expression of SJ‐CRIM, a major cross‐reactive idiotype which appears on polyclonal anti‐SEA antibodies generated during murine S. japonicum infection. The data indicate that for MoAbs of the IgG isotype which bound SEA by ELISA, the most immunosuppressive anti‐SEA MoAbs identified expressed SJ‐CRIM and were derived from naturally infected mice. All anti‐SEA MoAbs expressing SJ‐CRIM showed an identical banding pattern on immunoblot analysis which was abrogated by weak periodate treatment. The generation of expression of SJ‐CRIM on MoAbs using differing methodologies across an allotype barrier indicates that the expression of SJ‐CRIM is encoded by a germline gene. These data indicate an association between expression of this germline interstrain cross‐reactive idiotype and immunosuppressive capacity. In addition, the immunoregulatory network which develops during immune S. japonicum infection is initiated by a carbohydrate epitope(s) found on various SEA. These data have profound implications in the use of the cross‐reactive idiotype as a serodiagnostic tool in schistosomiasis.
Differential recognition of microfilarial antigens by sera from immigrants into an area endemic for brugian filariasis
Authors: KURNIAWAN L. , BASUNDARI E. , FUHRMAN J.A. , TURNER H. , PURTOMA H. , PIESSENS W.F.
Published: October 2007

Summary Studies in animal models indicate that antibodies to surface antigens of microfilariae participate in the control of parasitaemia resulting from infections with lymphatic filarial nematodes. In an attempt to identify parasite antigens that elicit such ‘protective’ host responses, we compared the antigen recognition patterns of persons who remained amicrofilaraemic after 3–6 years of exposure to Brugia malayi with those of individuals who developed patent filariasis during the same period. IgG antibodies in sera from immigrants identified between 0 and 25 microfilarial antigens on Western blots. The highest degree of reactivity was observed with antigens in the 65–75 kD and 20–30 kD ranges, and with a group of high mol. wt antigens (> 180 kD). Sera from amicrofilaraemic donors preferentially reacted with 70/75 kD microfilarial antigens. A proportion of such sera inhibited the binding of monoclonal antibody MF1 to its target epitope; eight of nine inhibitory sera were from patients with active infections, evidenced by the presence of microfilariae or filarial antigens in the donors' blood, but who were amicrofilaraemic. These results indicate that some amicrofilaraemic residents of areas where brugian filariasis is endemic develop immune reactions to a microfilarial stage‐specific antigen that was previously identified as a potentially ‘protective’ parasite antigen in animal models of lymphatic filariasis.
The identification of a species‐specific antigen from Necator americanus
Authors: PRITCHARD D.I. , McKEAN P.G. , ROGAN M.T. , SCHAD G.A.
Published: October 2007

Summary A 17 kD protein of Necator americanus was isolated by SDS‐PAGE and used to raise monospecific antisera in rabbits. ELISA and Western blotting against a range of parasite extracts demonstrated the species specificity of this protein. It is expressed at all stages of the life‐cycle, appears to be accumulated through the larval stages to adulthood, and can be localized in the oesophageal glands and cuticle of the adult parasite. The possible nature and diagnostic potential of this protein is discussed.
Differences in responses of rat‐ and guinea‐pig‐eosinophils to eosinophil chemotactic factors derived from Angiostrongylus cantonensis
Authors: ISHIDA KAZUTO , YOSHIMURA KENTARO
Published: October 2007

Summary Eosinophil chemotactic activity associated with whole worm extracts of the young adult worms (YA) and 1st stage larvae (L1) of Angiostrongylus cantonensis was assessed using guinea‐pig‐ and rat‐eosinophils. Both whole worm extracts were potently chemotactic to guinea‐pig‐eosinophils whereas only the whole worm extract of L1 was chemotactic to rat‐eosinophils. Gel filtration chromatography of YA‐whole worm extract yielded an eosinophil chemotactic factor (ECF‐YA) with an estimated molecular weight of 16900. ECF‐YA was resistant to heating and pronase digestion but sensitive to periodate oxidation, suggesting that chemotactic activity was possibly associated with the sugar portion of the glycoprotein molecule. Guinea‐pig‐ and rat‐eosinophils were deactivated by previous incubation with homologous whole worm extracts but not with heterologous ones. When guinea‐pig‐eosinophils were treated with trypsin or pronase, their chemotaxis to ECF‐YA was significantly inhibited, and pronase treatment was more effective. Both deactivated and trypsin‐treated guinea‐pig‐eosinophils completely recovered their chemotaxis responses after in vitro culture for 12 and 24 h, respectively. When those eosinophils were cultured in vitro in the presence of puromycin or cycloheximide, however, their chemotaxis responses could not be recovered. These data clearly indicate that guinea‐pig‐eosinophils probably possess a kind of receptor (or ‘recognition unit’) capable of reacting to ECF‐YA, and also that the receptor may be protein or glycoprotein molecules, and reproducible.
Lung‐phase immunity to Schistosoma mansoni: definition of alveolar macrophage phenotypes after vaccination and challenge of mice
Authors: MENSON ESSIE N. , WILSON R. ALAN
Published: October 2007

Summary Phenotypic changes in murine alveolar macrophages have been described in response to vaccination with irradiated cercariae and to a subsequent challenge with normal parasites. Flow cytometric analysis was used to quantify the proportions of cells strongly positive for a number of macrophage surface markers, detected by a panel of monoclonal primary antibodies and fluorescent secondary antibodies. The proportion of Ia+ macrophages sampled by bronchoalveolar lavage increased 5‐fold over days 14 to 28 post‐vaccination. This upregulation of Ia was accompanied by a sharp decrease in F4/80 expression between days 14 and 21. The low percentage of F4/80* cells persisted for several weeks after vaccination, and no further change was stimulated by challenge parasites. These altered characteristics are consistent with the ‘activation phenotype’ induced by other infectious agents. After challenge of immune mice, further changes in macrophage phenotype were slight compared to the responses elicited by vaccination, or to those induced in the challenge control group; la expression increased to about three times normal levels. The phenotypic changes correspond both in magnitude and timing with the pattern of alveolar macrophage activation determined in a previous study. The limited changes in phenotype of alveolar macrophages from immunized mice after challenge could indicate that these cells become refractory to reactivation. Overall, the altered macrophage phenotype after vaccination and challenge provides circumstantial evidence for the action of cytokines, particularly interferon‐gamma, in lung‐phase immunity to schistosomes.
Identification of a Theileria mutans‐specific antigen for use in an antibody and antigen detection ELISA
Authors: KATENDE J. M. , GODDEERIS B. M. , MORZARIA S. P. , NKONGE C. G. , MUSOKE A. J.
Published: October 2007

Summary Purified piroplasms of Theileria mutans were used to immunize BALB/c mice to generate monoclonal antibodies (MoAbs). The MoAbs recognized an antigen of a relative molecular mass of 32 kDa in Western blots. This antigen was also recognized by sera from cattle which had recovered naturally from experimental tick‐transmission or infections induced by the blood stages of T. mutans. The MoAbs did not react, in indirect immunofluorescence or enzyme‐linked immunosorbent assays (ELISA), with the common haemoparasites of cattle, namely, T. parva, T. annulata, Babesia bigemina, B. bovis, Anaplasma marginale, Trypanosoma congolense, T. vivax or T. brucei. An antigen capture ELISA was established with two of the MoAbs which recognized different epitopes on the 32 kDa molecule. Using this test it was possible to detect circulating antigens or immune complexes in sera collected from cattle during the acute or chronic phases of infection. When the purified 32 kDa protein was used as antigen in a micro‐ELISA to detect circulating antibodies in both experimental and field cattle sera, it was found that the titres of antibodies ranged between 1:20 and 1:10 240. Results of this study indicate that the antigen and immune complex capture assays and the antibody detection ELISA can be complementary in the immunodiagnosis of acute and chronic T. mutans infections. Moreover, the tests are useful in the differential diagnosis of the disease and for epidemiological studies.
Three non‐repeated transmission blocking epitopes recognized in the 21 kD surface antigen of zygotes‐ookinetes of Plasmodium berghei
Authors: TIRAWANCHAI NEDNAPIS , SINDEN ROBERT E.
Published: October 2007

Summary Two‐site and competitive ELISA have been developed against a surface antigen of zygotes‐ookinetes of Plasmodium berghei using monoclonal antibodies (MoAbs) which block transmission of the parasite to the mosquito. Three such MoAbs have been studied, each of which recognized a protein of an Mr 21 kD (Pbs21) using immunoblot techniques. The assays showed that there are at least 3 single B‐cell epitopes expressed in Pbs21. One epitope recognized by MoAb 17.9 is conformation dependent and antibodies bound to it interfered with other MoAbs (12.1 and 13.1) each recognizing a different, apparently linear epitope. Glycosylation might not be relevant to the binding of any of the antibodies tested to their respective epitopes.
Induction of immunity against Schistosoma mansoni by drug (Roll‐3128)‐terminated infections: analysis of surface antigen recognition
Authors: BICKLE Q.D. , SACKO M. , VIGNALI D. A. A.
Published: October 2007

Summary As with 20 krad‐irradiated infections in mice, the present study shows that the immunity induced by Ro11‐3128 termination of unattenuated infections at the skin stage is species specific, not operating against S. japonicum. Treatment with the drug Ro15‐5458, also effective at the skin stage, however, resulted in significantly lower levels of resistance than Ro11‐3128. Sera from mice immunized by infection plus Ro11‐3128 treatment on days 1 or 2 (Ro11S) coprecipitated essentially the same pattern of l25I‐labelled surface antigens as the 20 krad vaccine serum (VMS), viz. Mr 38000, 32000, 23000 and 15000. However, recognition by Ro11S was markedly stronger. Sera from the infected and Ro15‐5458‐treated mice (Ro15S) failed to recognize the Mr 23000 antigen and produced a weaker response than RollS or VMS against the Mr 38000 or 32000 antigens but a comparable response to VMS against the Mr 15000 antigen. Ro11S and VMS also recognized the Mr 16000 surface antigen seen by Western blotting but its recognition by Ro15S was weaker. Compared with sera from animals treated at the skin stage, sera from animals treated at the lung stage (day + 6) showed weaker recognition of the Mr 32 000 and 15 000 antigens and no recognition of the Mr 23 000 antigen. In contrast, sera from mice treated at 15 days recognized both the Mr 32 000 and 23 000 antigens but not the Mr 15 000 antigen. Mice treated at these times show progressively less immunity than at the skin stage. Infected but untreated animals only showed significant recognition of the Mr 32 000 antigen. Thus compared with infections treated with Ro11‐3128 on days 1 or 2, treatment at later times or with the drug Ro15‐5458 resulted in selective and differential absence or diminution of response against either the Mr 38 000, 32000, 23000, 16000 or 15000 antigens. In vitro, Ro11‐3128, in contrast to Ro15‐5458, caused multiple vesicle formation at the surface of skin stage schistosomula but this was progressively less pronounced with lung and liver stage worms. The vesicles were shown to express surface membrane antigens but were apparently not derived
Fasciola hepatica: immunoprecipitation analysis of biosynthetically labelled antigens using sera from infected sheep
Authors: SEXTON JENNIFER L. , MILNER ANDREW R. , CAMPBELL NOEL J.
Published: October 2007

Summary The antigenicity of the biosynthetically labelled somatic and excretory/secretory proteins of adult Fasciola hepatica was investigated over 20 weeks of an infection with F. hepatica in sheep. The antibody response was initially detected by 6LISA 2 weeks after infection, and was sustained at this level for the remainder of the infection. Immunoprecipitation analysis indicated that a large number of proteins were recognized by the sheep, with several dominant antigens occurring in the 29‐31 kilodalton molecular weight range. No differences were found between the antigens recognized by sheep in the early or late stages of infection suggesting that there are similarities between the antigens of the immature and mature forms of the parasite.
Molecular analysis of HLA DR4‐/β1 gene in malaria vaccinees. Typing and subtyping by PCR technique and oligonucleotides
Authors: MURILLO LUIS ANGEL , ROCHA CLAUDIA LUCIA , MORA ANA LUCIA , KALIL JORGE , GOLDENBERG ANA KARLA , PATARROYO MANUEL ELKTN
Published: October 2007

Summary The combination of the PCR technique and the synthetic oligonucleotides has proved to be a useful tool in the molecular analysis of HLA class II genes, allowing recognition of as little as a single nucleotide modification in the sequence of the gene. The molecules encoded by these genes have been associated with genetic control of the immune response and with susceptibility to certain diseases. Studies carried out in our laboratory have shown three patterns of humoral immune response in the human volunteers vaccinated with the synthetic protein SPf 66: high, intermediate and low responders. Approximately 73‐3% of the low responders were serologically typed as HLA DR4 and 42% as DQw6. These results moved us to look for a subtype (Dw) correlation between the DR4 positive individuals and the different humoral immune response patterns. Using oligo‐typing methods after previous amplification of the DR4 B1 exon, we subtyped 20 DR4 volunteers, classified as high, intermediate and low responders. We did not find any direct association between the HLA DR4 Dw special subtype in the high or low responders immunized with the SPf 66 vaccine.
Heterogeneity in the expression of surface‐exposed epitopes among larvae of Ascaris lumbricoides
Authors: FRASER ELEANOR M. , KENNEDY MALCOLM W.
Published: October 2007

Summary Quantitative immunofluorescence was used to examine differences in the binding of antibody to the surface of individual living infective stage larvae of Ascaris lumbricoides. Using rabbit antisera, it was first established that larvae cultured for 48 h after artificial hatching were relatively uniform in their levels of antibody binding and in minimal exposure of epitopes expressed by later larval stages. Aliquots from a pool of larvae were probed with serum from individual infected people living in an endemic area of Nigeria. The larvae used were derived from parasites collected in the same geographical area in which serum donors were living. Two principal points emerged. First, serum donors varied considerably in the degree to which their antibody bound to the larvae. Secondly, the binding of antibody from a given donor revealed remarkable heterogeneity in surface epitope expression. Such intra‐specific variability in antigen expression has considerable implications for the development of immunity to parasitic nematodes.
Susceptibility of N'Dama and Boran cattle to tsetse‐transmitted primary and rechallenge infections with a homologous serodeme of Trypanosoma congolense
Authors: PALING R.W. , MOLOO S.K. , SCOTT J.R. , MCODIMBA F.A. , ENFREY L.L.LOGAN‐H , MURRAY M. , WILLIAMS D.J.L.
Published: October 2007

Summary Eight trypanotolerant N'Dama cattle controlled an infection of Trypanosoma congolense IL Nat 3.1 transmitted by Glossina marsitans centralis, more efficiently than a group of similarly infected trypanosuscepliblc Boran cattle. All eight N'Damas maintained their PCV above 15% throughout the primary infection whereas the PCV of six of the eight Borans dropped below 15%; these latter animals were treated with diminazene aceturate to prevent possible death. Lymphocyte, neutrophil and platelet counts also decreased in the Boran during the primary infection. In contrast, a lymphocytosis was observed in the N'Dama; and although the neutrophil and platelet counts decreased, the drop was less severe than in the Boran. Two years after the primary infection and immediately prior to a homologous rechallenge infection, all eight N'Damas had neutralizing anti‐metacyclic trypanosome variant‐specific antibodies present in their sera compared to five of the eight Borans. Following the homologous rechallenge infection the eight N'Damas became parasitacmic but there were no alterations in their erythrocyte or leukocyte counts. The Borans became highly parasitacmic and developed severe, chronic anaemia and leukopacnia. Thus, the trypanotoleranl N'Damas controlled a primary infection of T. congolense more efficiently than trypanosusceptible Boran cattle and eliminated a homologous rechallenge infection without the pathology associated with the disease.
Cellular responses to phase fractions of Trypanosoma lewisi
Authors: NDARATHI C.M.
Published: October 2007

Summary Infections by Trypanosoma lewisi are characterized by hyporesponsiveness of the immune system during the early phase of parasitaemia. Blastogenic response of normal rat spleen cells to amphiphilic and hydrophilic components of Triton X‐114 solubilized epimastigote forms of T. lewisi which characterizes the early phase of infection showed that suppression of responses to mitogens Concanavalin A (Con‐A) and lipopolysaccharide (LPS) occurred exclusively with the amphiphilic fraction that consists of integral surface membrane constituents. The Con‐A‐induced suppression by the amphiphilic constituents was ablated by addition of exogenous IL‐2 or by the removal of the adherent cell population in the cultures. This suggests that the integral surface membrane components play an important regulatory role in infections with Trypanosoma lewisi, through complex mechanisms that probably involve the B cells and suppressor macrophages; the suppressor macrophages probably produce a suppressor factor that inhibits the proliferation of T helper cells and subsequently the production of interleukin‐2.
Lysis of pathogenic and nonpathogenic Entamoeba histolytica by human complement: methodological analysis
Authors: HAMELMANN CHRISTOPH , FOERSTER BIRGIT , BURCHARD GERD D. , HORSTMANN ROLF D.
Published: October 2007

Summary The effect of nonimmune human serum on Entamoeba histolytica trophozoites was studied: (a) using whole serum in the presence of Ca and Mg ions allowing complement activation via both the alternative and classical pathways or in the presence of MgEGTA permitting alternative pathway activation only; (b) using different E. histolytica isolates; (c) varying serum and trophozoite concentrations and the time of incubation; and (d) using three different methods to quantify lysis, i.e., microscopic inspection, flow cytometry and 111In release. All three methods yielded similar results, with flow cytometry being most sensitive in identifying membrane damage and 111In release being most valid in determining cell death. Microscopic analysis was reliable only when a chamber was used to calculate the number of complement treated cells in relation to the initial cell count. E. histolytica isolates were classified into three groups according to their susceptibility to lysis by complement: (i) pathogenic isolates after long term cultivation in vitro were susceptible; (ii) pathogenic isolates after recent in vivo passage were less susceptible; and (iii) nonpathogenic isolates were nearly unaffected by exposure to the alternative pathway alone. The extent of lysis of the various isolates correlated with the degree of complement consumption in the serum samples, suggesting that unlysed isolates did not activate complement under the conditions employed. In general, lysis of susceptible trophozoites increased with the serum concentration and with the time of incubation. However, when the trophozoite concentration was 106/ml or higher, lysis no longer reflected complement susceptibility because of exhaustion of the complement supply.