bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibody isotypes in human schistosomiasis mansoni
Authors: JASSIM A. , HASSAN K. , CATTY D.
Published: October 2007

Summary Summary Schistosoma mansoni‐infected subjects from the Gezira Irrigated Area of Sudan were studied for serum immunoglobulin levels, and specific antibody titres to larval, adult and egg stage antigens, by class and IgG subclass. The 276 subjects were adult chronic cases (frequently exposed male canal cleaners), primary school children, and hospital‐referred cases with acute symptoms including hepatosplenomegaly. Chronic untreated cases were compared with a similar group of canal cleaners 3 months after successful chemotherapy with Praziquantel administered at the start of the non‐transmission season. All cases, except those previously treated, were egg positive at the time of blood sampling. Data from infected and treated cases were compared with measurements of serum immunoglobulin in a panel of European blood donors. The major findings are as follows:

There is a consistently elevated total serum IgG concentration in infected groups which is accounted for mainly by an increased IgG1 subclass (greatest in chronic cases) and by a remarkable 10‐to 11‐fold increase in IgG4 in the untreated chronically infected group and in the schoolchildren.

All infected groups showed high IgG antibody responses to all life cycle stage antigens, and IgM titres were high to adult and egg antigens in untreated canal cleaners. Major differences were evident in the distribution of IgG subclass antibodies between the infected groups: the response to larval and adult antigens is poor or absent in IgG1, IgG2 and IgG3 in untreated chronic infections but is high in IgG4, whereas in acute cases with hepatosplenomegaly and in schoolchildren IgG1, IgG2 and IgG3 antibodies to larval antigens are in high titre but IgG4 and IgM responses to larvae are low or absent, the response in these isotypes being restricted in these cases to adult and egg antigens. Comparing the treated and untreated canal cleaners, although these are separate groups, the data suggest that Praziquantel reduces total serum IgA and IgM levels but has little effect on the raised IgG component except for the IgG4 subclass. The treated chronic cases show a reversal in the ratio of IgG1, IgG2 and IgG3 to IgG4 antibodies to larval and adult antigens compared with the untreated chronic group—the IgG4 response being low by 3 months after treatment and the IgG1, IgG2 and IgG3 being high. These data are discussed in relation to the possible importance of antibody isotype selection in determining host susceptibility to infection, with reference to age, exposure and treatment of the host.
The biotin‐streptavidin system in a two‐site ELISA for the detection of plasmodial sporozoite antigen in mosquitoes
Authors: VERHAVE J.P. , LEEUWENBERG A.D.E.M. , PONNUDURAI T. , MEUWISSEN J. H. E. Th. , VAN DRUTEN JAM.
Published: October 2007

Summary A two‐site ELISA has been designed for the detection of sporozoite antigen in mosquitoes. Biotin‐labelled monoclonal antibodies against sporozoites and a streptavidin‐biotin‐peroxidase complex were used to visualize the antigen.

Evaluation of the sensitivity and specificity of the procedure was carried out and background levels of reactivity on the basis of negative mosquitoes were calculated. The test has been deliberately kept as simple as possible for use in the tropics and was designed using Anopheles stephensi infected with in vitro cultivated Plasmodium falciparum gametocytes.

A minimum of about 100‐350 sporozoites could be detected in mature salivary gland infections; in addition sporozoite antigen was detected in mosquitoes several days before the entry of sporozoites into the salivary glands. No reaction was demonstrable either with bloodstage or ookinete antigens of P. falciparum, or with mosquitoes carrying sporozoites of other plasmodial species. The number of sporozoites in positive mosquitoes and the generating capacity of a single oocyst could be assessed by the use of a calibration curve based on dilution data of a known sporozoite suspension. It was found that a single oocyst can produce about 10 000 sporozoite equivalents.
Suppression of mucosal mastocytosis by Nematospiroides dubius results from an adult worm‐mediated effect upon host lymphocytes
Authors: DEHLAWI M.S. , WAKELIN D.
Published: October 2007

Summary Infections with the nematode Nematospiroides dubius fail to elicit mucosal mast cell (MMC) responses in the intestines of host mice, and suppress MMC responses generated by heterologous infection. Larval N. dubius have the capacity to prime for mastocytosis, and to elicit this response in primed mice during a challenge, but only if adult worms are prevented from developing, either by anthelmintic treatment or by irradiation of the larvae themselves. The suppressive effect of the adult stage was confirmed in experiments where such worms were implanted directly into the intestines of mice primed by exposure to irradiated N. dubius larvae or concurrently infected with Trichinella spiralis. Data on the mechanisms underlying this suppressive effect were obtained from experiments involving the adoptive transfer of mastocytosis by mesenteric lymph node cells (MLNC) from T. spiralis infected mice. When MLNC were taken from mice infected concurrently with both T. spiralis and N. dubius no enhanced mastocylosis was seen in recipients after challenge with T. spiralis. Exposure of M LNC from T. spiralis infected donors to the presence of adult N. dubius after transfer did not reduce the adoptively transferred response. The response was also unaffected when MLNC from adult N. dubius infected mice were simultaneously transferred with MLNC from T. spiralis donors. It is concluded that the suppressive effect of adult N. dubius upon the expression of mucosal mastocytosis acts upon the generation of lymphocytes capable of promoting the development of MMC from precursor cells.
Studies on stage‐specific immunity against Taenia Taeniaeformis metacestodes in mice
Authors: Bøgh Henrik O. , Rickard Michael D. , Lightowlers Marshall W.
Published: October 2007

Summary The possible existence of stage‐specific immune responses to Taenia Taeniaeformis infection was investigated in C3H/He mice vaccinated with antigens prepared from either the oncosphere or metacestode stages. Mice were immunized twice, 2 weeks apart, with antigen in Freund'B complete adjuvant. Two weeks after the second immunization they were challenged with 250 T. Taeniaeformis eggs and killed day 0, 5, 10, 15, 20, 25, 30, 45 and 60 after infection. Gross examination of the livers revealed marked differences between oncosphere (TtO) and metacestode (TtM) vaccinated mice. Very few metacestodes were found in the first group but most of those that evaded the initial host attack developed like the cysts found in the control group. In contrast, many degenerating metacestodes were found in the TtM vaccinated group. In a subsequent experiment groups of mice were vaccinated with varying doses of either TtO or TtM to determine whether the qualitative differences observed above were due to antigen dose effects. However, varying antigen doses gave the same results. These data show that vaccination with oncospheres generates an immune response capable of killing invading larvae soon after infection whereas vaccination with TtM results in larvae being killed at a later stage, suggesting that there are stage‐specific, host‐protective antigens.
Antigenic cross‐reactivity between the human whipworm, Trichuris trichiura, and the mouse trichuroids Trichuris muris and Trichinella spiralis
Authors: Roach T.I.A. , Wakelin D. , Else K.J. , Bundy D.A.P.
Published: October 2007

Summary Cross‐reactivity was demonstrated between circulating antibodies from Trichuris trichiura‐infected humans and T. muris‐infected mice for heterologous antigen preparations. Mouse immune sera raised against excretory/secretory (E/S) products and anterior end homogenate from adult T. muris showed marked affinity for T. trichiura adult homogenate in ELISA, and 35S‐methionine‐labelled adult T. muris E/S products were precipitated by T. trichiura infection sera. Monoclonal antibodies recognizing a 48 kD Trichinella spiralis muscle larval β‐stichocyte granule antigen also showed avidity for T. trichiura adult homogenate in ELISA, as did scrum from mice with patent T. muris worm burdens. This cross‐reactivity is thought to result from shared stichocyte antigens and the relevance of this observation is discussed.
Antibody‐mediated in‐vivo cytotoxicity to Trichinella spiralis newborn larvae in immune rats
Authors: WANG CHING HUA , BELL R.G.
Published: October 2007

Summary The antibody‐dependent cell‐mediated larvicidal response of AO rats against Trichinella spiralis newborn larvae was studied in vivo. Rats were immunized with 2000‐3000 muscle larvae orally and then challenged 6‐20 days later with 10 000‐20 000 newborn larvae intraperitoneally. Newborn larvae recovery from the peritoneal cavity decreased significantly and was accompanied by cuticular cell adherence and killing of newborn larvae by day 9 of infection. Similar effects were observed when newborn larvae were incubated with blood obtained from immunized rats. The cell adherence and larvicidal responses reached their peak by day 16 of the primary infection. Passive transfer experiments demonstrated that newborn larvae infectivity was substantially impaired once cell adherence occurred. Culicular adherence took place in vitro only when immune serum was added to the incubation medium. Complete destruction of newborn larvae in vivo after passive transfer, as measured by muscle larvae burden was only evident after exposure to both immune serum and immune cells, not to either alone. Non‐specific stimulation of the peritoneal cavity with a sterile intestinal infection failed to induce cuticular adherence or larval killing in these rats. We conclude that a stage‐specific antibody‐dependent cell‐mediated larvicidal response is rapidly generated in vivo after the host is exposed to newborn larvae. It is a systemic response which impairs the infectivity of newborn larvae and can destroy them before they reach muscle tissue.
Parasite‐specific immune responses to Onchocerca lienalis microfilariae in normal and immunodeficient mice
Authors: CARLOW CLOTILDE K.S. , DOBINSON A.R. , BIANCO A.E.
Published: October 2007

Summary The model of Onchocerca lienalis microfilariae (mf) in CBA mice has been employed to examine the immunological mechanisms underlying the destruction of skin‐dwelling mf in onchocerciasis. Comparative studies among tmmunologically intact (CBA/H) or deficient (CBA/N, T‐cell‐deprived) syngeneic animals demonstrated that levels of mf of a primary infection were reduced most rapidly in fully immunocompetent mice. Significant reductions in recoveries of a secondary infection were evident in CBA/H (80%) and CBA/N (44%) mice, but not in T‐cell‐deprived animals. The establishment of primary and secondary infections was apparently not influenced by complement, as judged by C3 depletion with Cobra Venom Factor. Eosinophilia was demonstrated to varying degrees in all infected animals; similar levels occurred in CBA/H and CBA/N mice which were greatly elevated after mf challenge. In contrast, the eosinophil response of T‐cell‐deprived mice was weak and not potentiated during secondary infection. Type I immediate hypersensitivity responses to soluble mf antigen (mf‐Ag) were mounted by all groups, but significantly less strongly in T‐cell‐deprived mice. Type IV delayed responses were generally weak, although CBA/N mice reacted strongly in the early phase of primary infections. During the first 2 weeks of infection CBA/H and T‐cell‐deprived mice mounted rapid IgM responses to mf‐Ag. Subsequently, levels of IgG2a, IgG2b and IgGI increased in all mice. There was a potentiated IgG2a, IgG2b and IgG I response in all groups following challenge, with levels of IgGJ highest in CBA/H mice. IgE responses were also detected by passive cutaneous anaphylaxis during primary and secondary infections. Peak levels of parasite‐specific antibodies coincided with the timing of mf clearance.
Specificity of Toxocara ELISA in tropical populations
Authors: LYNCH N.R. , WILKES L.K. , HODGEN A.N. , TURNER K.J.
Published: October 2007

Summary The diagnosis of human infection by Toxocara canis relies heavily upon serological tests, the specificity of which can be inadequate in regions of endemic helminthiasis. When different population groups of tropical Venezuela were evaluated using ELISA based upon Toxocara excretory‐secretory antigen (TcES A), solid‐phase adsorption of the sera with extracts of a wide variety of non‐homologous parasites revealed the existence of significant cross‐reactivity. This was effectively and conveniently overcome when the test sera were incubated in the presence of the soluble parasite extracts in a competitive inhibition ELISA. The mean reduction of ELISA values caused by pre‐adsorption of the sera tested was 32‐2%, and that caused by competitive inhibition was 42‐3%, the effects of these two procedures being strongly correlated (r=0.83). The magnitude of the reduction was inversely proportional to the actual ELISA value (r=‐0.55), and ranged from a mean of 68.0% in sera from apparently healthy individuals of medium‐high socio‐economic level, down to 28.1% in heavily parasitized Amazon Indians. Ascaris showed the greatest degree of cross‐reactivity in these tests, although under conditions of competitive inhibition even sera with high levels of antibody against this parasite could be negative in Toxocara ELISA. Western blotting revealed a major 81 400 D component that was shared between Ascaris and TcESA.

Our results indicate that the competitive inhibition of cross‐reactivity by soluble non‐homologous parasite extracts provides a convenient and economical means of increasing the specificity of ELISA for the determination of the seroprevalence of toxocariasis in tropical populations.
Mature liver stages of cloned Plasmodium falciparum share epitopes with proteins from sporozoites and asexual blood stages
Authors: SZARFMAN ANA , ALYON JEFFREY , WALLIKER DAVID , QUAKYI ISABELLA , HOWARD RUSSELL J. , SUN SUSAN , BALLOU W. RIPLEY , ESSER KLAUS , LONDON WILLIAM T. , WIRTZ ROBERT A. , CARTER RICHARD
Published: October 2007

Summary The liver mcrozoites of malaria parasites arc of paramount importance, as they initiate the parasite invasion of red blood cells and start the cycle associated with the clinical features of malaria. Investigating liver merozoite antigen is difficult because of the lack of a rodent model of human malaria. In addition, only a low proportion of cells are obtained in vivo, the parasites from Cebus and Aotus monkeys are immature, and in‐vitro experiments with liver cells are often confounded by contamination with the natural mosquito flora co‐purified with the sporozoites used for seeding the liver cultures.

In our study, mature liver schizonts were shown to possess many of the antigenic determinants recognized by MoAbs and sera specific for defined sporozoite and blood‐stage antigens. We employed an immunofluorescence procedure based on evaluating parasites in cryosections prepared from infected chimpanzee liver. Sufficient numbers of sectioned parasites were evaluated with each antibody to assure the reproducibility of the results, and the fixation procedure used was sufficiently non‐destructive to parasite antigens so that clear differences between reactions of specific antibodies and negative controls were observed.

Our evidence for sharing of epitopes by liver merozoites and sporozoites or by liver merozoites and asexual blood‐stage parasites raises the possibility that immune responses elicited against sporozoites or asexual stage antigens being considered as vaccine candidates may also act against this important, little‐studied stage of the parasite.
Reactivity of stage‐specific monoclonal antibody 1G7 with metacyclic trypomastigotes of Trypanosoma cruzi strains: lytic property and 90 000 mol. wt surface antigen polymorphism
Authors: MORTARA RENATO A. , ARAGUTH MARCIA F. , YOSHIDA NOBUKO
Published: October 2007

Summary Eleven strains of Trypanosoma cruzi, originating from a variety of vertebrate and invertebrate hosts in distinct geographical regions, were examined for the reactivity of metacyclic stages with the monoclonal antibody 1G7. Trypomastigotes of five strains were susceptible to complement‐dependent 1G7‐mediated lysis. Higher levels of 1G7 bound to metacyclics of lysis‐susceptible strains as compared to lysis‐resistant isolates. Excluding Y and CL strains, 1G7 reacted with metacyclics of all T. cruzi isolates by binding to a 90 000 mol. wt surface polypeptide. A 90 000 mol. wt protein lacking the lG7‐specificcpitope but immunologically related to the 90 000 mol. wt antigen of other T. cruzi isolates is present in Y and CL strains. The intensity of the 90 000 mol. wt band, delected by surface lodination of metacyclics or in immunoblots using the monoclonal antibody IG7 or the monospecific antiserum to 90 000 mol. wt protein, varied among different strains and also a discrete variation was observed in its molecular weight. The overall analysis reveals a polymorphism of the 90 000 mol. wt protein, which is ubiquitous among the different T. cruzi isolates.
Tvichostrongylus colubriformis: analysis of monoclonal antibody and lectin binding to the larval cuticle
Authors: MILNER A. R. , MACK W. N.
Published: October 2007

Summary A monoclonal antibody (VRI 86‐1) raised against third stage Trichostrongylus colubriformis preferentially bound to the excretory pore of living exsheathed larvae, with little or no binding to other sites on the parasite surface. A similar binding pattern was observed with fluorescein‐labelled wheat germ agglutinin (WGA), although the anterior end of the parasite was also stained. To gain information at the molecular level regarding the parasite components at these sites, the residues recognized by WGA (i.e. N‐acetylglucosamine and N‐acetylneuraminic acid) were radiolabelled on the surface of living larvae. After homogenization and detergent extraction of the larvae, Tour dominant bands and a number of minor bands were revealed by SDS‐PAGE and fluorography. None of these bands was specifically immunoprecipilated or recognized on a Western blot by VRI 86‐1, suggesting that the epitope recognized by this antibody either resides on a different molecule or is destroyed or changed during the radiolabelling procedures. These results provide further evidence that the nematodc cuticle is not uniform at the molecular level, and that the excretory pore contains molecules and antigens that may be unique to that site.
Proteinase phenotypes and fixation properties of rat mast cells in parasitic lesions caused by Mesocestoides corti: selective and site‐specific recruitment of mast cell subsets
Authors: CHERNIN J. , MILLER H.R.P. , NEWLANDS G.F.J. , MCLAREN DIANE J.
Published: October 2007

Summary The distribution, fixation properties, and protease phenotypes of mast cells populating lesions caused by the metacestode stage of the cestode Mesocestoides corti in the rat were characterized. Intraperitoneal infection with M. corti induced severe granulomatous types of reactions around the pancreas and further lesions in the liver. These sites were infiltrated with mast cells which contained cither rat mast cell protease I or II derived respectively from connective tissue (CTMC) or mucosal mast cells (MMC). A proportion of cells in pancreatic granulomas had staining and fixation properties identical to those of intestinal mucosal mast cells; others were typical connective tissue mast cells. Subcutaneous inoculation of parasites was associated with nodular dermal reactions, and all of the infiltrating mast celts had the fixation and staining properties of CTMC and contained RMCPI uniquely. Increased numbers of RMCPII‐containing mast cells were present in the intestines of rats infected intraperitoneally. Significant quantities of RMCPII were present in homogenates of pancreatic granulomas and in livers of rats harbouring intraperitoneal infections but none was detected in skin. These findings suggest that mast cells of different phenotypes arc selectively recruited to some, but not all, lesions.
Circumsporozoite protein of Plasmodium gallinaceum characterized by monoclonal antibodies
Authors: KRETTLI A.U. , ROCHA E.M.M. , LOPES J.D. , CARNEIRO C.R.W. , KAMBJ K.K. , COCHRANE A.H. , NUSSENZWEIG R.S.
Published: October 2007

Summary Monoclonal antibodies (MoAb) were produced against both salivary gland sporozoites (SGS) and oocyst sporozoites (OS) of Plasmodium gallinaceum, an avian malaria parasite. By indirect immunofluorescence, all of the MoAbs reacted with both SGS and OS of P. gallinaceum and two of the MoAbs cross‐reacted weakly with P. berghei sporozoites. None of the MoAbs reacted with sporozoites of six additional species of mammalian plasmodia. In Western blot analysis of extracts of either SGS or OS of P. gallinaceum, these MoAbs identified two polypeptides with molecular weights of approximately 76000 and 64000 D. The results of a MoAb inhibition of binding assay and a two‐site one‐antibody immunoradiometric assay indicate that the circumsporozoite protein of P. gallinaceum, like those of mammalian malaria parasites, contains a repetitive immunodominant epitope. Two of the anti‐P. gallinaceum MoAbs were tested in a sporozoite neutralization assay and decreased, but did not abolish, the infectivity of sporozoites for chickens, indicating that the polypeptide of P. gallinaceum identified by immunoblot is probably the protective antigen.
Induction of a protective antibody‐dependent response against toxoplasmosis by in vitro excreted/secreted antigens from tachyzoites of Toxoplasma gondii
Authors: DARCY F. , DESLEE D. , SANTORO F. , CHARIF H. , AURIAULT C. , DECOSTER A. , DUQUESNE V. , CAPRON A.
Published: October 2007

Summary Toxoplasma gondii is a worldwide protozoan parasite which causes severe disease in congenitally infected children and in immunocompromised patients. Besides the well‐defined cytoplasmic and membrane antigens of tachyzoites, we felt that excreted/secreted antigens could play a major role in the immune response. We first report the development of a well‐controlled procedure for obtaining tachyzoite excreted/secreted antigens (E/SA) in cell‐free incubation media. The E/SA immunogenic in human, rat and mouse toxoplasmosis were then characterized. The major E/SA recognized by human sera from the chronic phase of toxoplasmosis had molecular weights of 108, 97, 86, 69,60, 57, 42, 39, 28.5, 27 and 26 kD. When injected into +/+ Fischer rats, E/SA elicited high antibody titres. In addition, passive transfer of these sera to highly susceptible nu/nu littermates induced a significant degree of protection towards the virulent RH strain of T. gondii. This work, which demonstrates the key role played by E/SA in the protective immune response, suggests that these antigens should be of value both for diagnostic purposes and for the development of new strategies for immunization against toxoplasmosis.
Macrophage‐mediated cytostasis and lymphocyte cytotoxicity in cattle immunized with Theileria annulata sporozoites or macroschizont‐infected cell lines
Authors: PRESTON PATRICIA M. , BROWN C. G. D.
Published: October 2007

Summary Immunization with either sporozoites or macroschizont‐infected cell lines protected calves against challenge with lethal doses of sporozoites of Theileria annulata. Stocks from India, Turkey and Morocco all conferred protective immunity to each other, irrespective of the immunizing regime. Although heterogeneous clinical responses were induced by the two immunizing regimes, both stimulated similar patterns of macrophage cytostasis as expressed as an inhibition of proliferation of macroschizont‐infected cell lines. Macrophage cytostasis was detected consistently after immunization and after challenge, arising at the same time as macroschizonts were detectable. Its expression was sustained and inhibited the proliferation of both autologous and allogeneic (BoLA‐mismatched) cell lines. In contrast, these two immunizing regimes differed in their ability to stimulate the production of cytoloxic cells. Calves immunized with autologous cell lines or sporozoites developed very transient populations of cytotoxic cells expressing only a low level of specific lysis for autologous infected cells; agglutinating antibodies for immunizing or autologous cell lines were not detected in these calves. Calves immunized with aliogeneic cell lines produced cytotoxic cells which were specific only for the immunizing cell lines; these calves also produced antibodies which agglutinated the immunizing cell lines.
The effect of immunosuppression with dexamethasone on Haemonchus contortus infections in genetically resistant Merino sheep
Authors: PRESSON B.L. , GRAY G.D. , BURGESS S.K.
Published: October 2007

Summary The effect of immunosuppression with the glucocorticosteroid, dexamethasone, on the susceptibility to Haemonchus contortus infection of a highly resistant Merino genotype was investigated. Higher faecal egg counts, larger worm burdens and heavier worms were recorded in immunosuppressed wethers. The characteristic globule leucocyte infiltrate in the abomasum of resistant wethers (12‐month‐old castrated males) was absent in immunosuppressed animals. Treatment with dexamethasone abolished differences between resislanl and susceptible genotypes in faecal egg counts, worm weights, thymus weights and globule leucocyte responses to infection with H. contortus. These results suggest that an immunological basis underlies the high level of resistance to infection in the resistant genotype.
Cross–reactive antigenic determinants present on different Plasmodium falciparum blood–stage antigens
Authors: MATTEI DENISE , BERZINS KLAVS , WAHLGREN MATS , UDOMSANGPETCH RACHANEE , PERLMANN PETER , GRIESSER HANS WERNER , SCHERF ARTUR , MÜJLLER–HILL BENNO , BONNEFOY SERGE , GUILLOTTE MICHELINE , LANGSLEY GORDON , SILVA LUIZ PEREIRA DA , MERCEREAU–PUIJALON ODILE
Published: October 2007

Summary A gene encoding a previously undescribed antigen of Plasmodium falciparum has been isolated from a genomic expression library by use of a pool of human immune sera. Northern blot analysis indicated that the gene is expressed at the late stages of the intra–erythrocytic cycle. This antigen, 332, contains a series of degenerated amino acid repeats. Human antibodies affinity–purified on the 332 recombinant antigen reacted with a family of parasite proteins that are products of different genes. We identified antigens 11.1 and Pf 155–RESA as members of this family and confirmed, using a human monoclonal antibody, the presence of cross–reacting determinants. The sequences of these antigens also share some structural homologies. The significance of this family of blood–stage antigens is discussed.
The development and specificity of cytotoxic cells in cattle immunized with autologous or allogeneicTheileria annulata–infectedlymphoblastoid cell lines
Authors: INNES E. A. , MILLAR P. , BROWN C.G.D. , SPOONER R. L.
Published: October 2007

SummaryTwo groups of animals were immunized with either 106autologous or 106allogeneicTheileria annulata–nfected lymphoblastoid cells culturedin vitro.The development and specificity of cytotoxic cells generatedin vivowere measured throughout immunization and challenge using a panel of target cells that were eitherTheileria–fected or uninfected blast cells of known bovine lymphocyte antigen (BoLA) specificities. After inoculation of the cell lines the two groups showed distinct differences in both their clinical responses and the target specificity of the cytotoxic cells detected. The allogeneicT. annulatacell line recipients showed a very mild clinical response, and on day 9 after inoculation a strong cytotoxic response was detected. The response appeared to be directed against the allogeneic major histocompatibility complex (MHC) antigens of the inoculated cell line in some form of graft rejection response. By day 23 the predominant cytotoxic response was directed against the recipient animals' own cells infected with the parasite. In contrast, the autologousT. annulatacell line recipients showed very severe clinical reactions, and low levels of cytotoxicity were detected. The cytotoxicity was directed against parasite–infected targets but did not appear to be MHC restricted until day 20. Both groups were immune to a heterologous sporozoite challenge that proved lethal to two susceptible control animals, and on day 10 after challenge a peak of cytotoxicity was detected which was directed against the autologous infected target cell. This would suggest that this cytotoxic response was MHC restricted and was also cross–reactive between the heterologous parasite stocks used.
Free radical generation during primary infections with Nippostrongylus brasiliensis
Authors: SMITH N. C. , BRYANT C.
Published: October 2007

Summary The production of free radicals during infection of the rat with Nippostrongylus brasiliensis was investigated. Lipid peroxidation, which is the best documented effect of free radicals, was monitored in the small intestines of infected rats by measurement of malonyldialdehyde and was found to be increased at the time of worm rejection. The capacity of peritoneal leucocytes to produce free radicals, as measured by chemiluminescence, was monitored in rats infected with different doses of N. brasiliensis. Rejection of N. brasiliensis from rats infected with 6000 third–stage larvae (L3) began 2 days earlier than in rats infected with only 600 L3. Maximal free radical generation also occurred 2 days earlier and was quantitatively greater in rats infected with 6000 L3. Free radical generation by leucocytes in response to live adult N. brasiliensis was enhanced by plasma from infected rats indicating the existence of a plasma–borne factor responsible for the initiation of free radical generation in response to N. brasiliensis.
In‐vitro exoerythrocytic development of Plasmodium cynomolgi bastianellii inhibitory activity of monoclonal antibodies against sporozoites of different P. cynomolgi strains and of P. knowlesi
Authors: MILLET PASCAL , KAMBOJ KAMAL K. , COCHRANE ALAN H. , COLLINS WILLIAM E. , BRODERSON J. ROGER , BROWN BOBBY G. , NGUYEN‐DINH PHUC
Published: October 2007

Summary The inhibitory effect of anti‐sporozoite monoclonal antibodies (MoAb) on the in‐vitro development of liver stages of Plasmodium cynomolgi bastianellii (NIH strain) was evaluated using primary cultures of rhesus monkey hepatocytes. MoAbs against the circumsporozoite proteins of five strains of P. cynomolgi (NIH, London, Gombak, Ceylon, Berok), and of P. knowlesi(H strain) were used. Incubation of sporozoites of P. cynomolgi bastianellii with the anti‐NIH strain MoAbs entirely prevented liver‐stage development; MoAbs produced against the other four strains had no apparent activity. The anti‐P. knowlesi MoAbs had a partially inhibitory effect on parasite development. These functional studies complement previous immunological studies on P. cynomolgi strain specificity, and confirm the cross‐reactivity observed previously between sporozoites of P. cynomolgi bastianellii and P. knowlesi (H strain).
Immunity to coccidiosis: T‐cell control of infection with Eimeria vermiformis in mice does not require co‐operation with inflammatory cells
Authors: ROSE M. ELAINE , WAKELIN D. , JOYSEY H. S. , HESKETH PATRICIA
Published: October 2007

Summary The necessity for co‐operation between lymphocytes and myeloid‐derived inflammatory cells in the mediation of anti‐coccidial immunity was investigated using mice infected with Eimeria vermiformis. Reciprocal exchange of immune lymphocytes between H‐2 compatible strains of contrasting susceptibility to infection (resistant BALB/B and susceptible C57BL/10) resulted in successful transfer of immunity in both homologous and heterologous exchanges. Recipients of immune cells, whatever their original response phenotype, expressed a high degree of immunity to infection, indicating that the differential susceptibility of the strains is a property of their lymphoid cells and is not attributable to their capacity to mount inflammatory responses. This conclusion was confirmed by the successful adoptive transfer of immunity into NIH mice previously exposed to 600 rad X‐irradiation; at this level of irradiation inflammatory responsiveness is severely depressed. Additional confirmation that strain‐response phenotype is lymphocyte dependent and that immune lymphocytes can mediate their effects against E. vermiformis without the intervention of inflammatory cells was obtained from studies on the mucosal mast cell response to infection. No correlation existed between the development of intestinal mastocytosis, an index of T‐cell‐mediated inflammatory responsiveness, and the expression of resistance to E. vermiformis in BAL/c (resistant), C57BL/10 (susceptible) and NIH (susceptible) mice.
Variable species and stage specificity of schistosomulum surface epitopes recognized by mice vaccinated with highly irradiated cercariae
Authors: ALI PIRLANTA OMER , HAGAN PAUL , HACKETT FIONA , SMITHERS S. RONALD , SIMPSON ANDREW J. G.
Published: October 2007

Summary Antibodies from mice vaccinated with highly irradiated Schistosoma mansoni or S. haematobium cercariae were used to characterize schistosomulum surface epitopes which were found to be diverse in their species and stage specificities. The epitopes recognized on the Mr > 200 000 and 15 000 schistosomulum surface antigens of S. mansoni and the Mr > 200 000 schistosomulum surface antigen of 5. haematobium were found to be cross‐specific whereas those on the Mr 38 000, 32 000 and 20 000 schistosomulum surface antigens of 5. mansoni and the Mr 35000, 30000 and 24000 schistosomulum surface antigens of S. haematobium were only immunoprecipitated by homologous antibody and are thus possible targets of the protective species‐specific immunity stimulated by highly irradiated cercariae. The epitopes recognized on the Mr > 200000 and 38 000 antigens of S. mansoni were shown to cross‐react with both the egg and the adult worm whereas those on the Mr 32 000 and 20 000 antigens only cross‐reacted with the adult worm, and those on the Mr 15000 antigen cross‐reacted with neither the adult worm nor the egg. In addition the epitopes on the Mr 38 000 and 32000 antigens were demonstrated to be polypeptide in nature. Those on the Mr > 200 000, 20000 and 15 000 antigens, on the other hand, could not be conclusively defined.
Schistosoma bovis as an immunological analogue of S. haematobium
Authors: AGNEW ALISON M. , MURARE H. M. , LUCAS S. B. , DOENHOFF M. J.
Published: October 2007

Summary The host‐parasite relationships of Schistosoma bovis and S. haematobium have been compared in normal and T‐cell‐deprived mice, and have been found to contrast with that of S. mansoni. Deprived mice infected with either of the former two schistosome species survived as long as, or longer than, comparably infected immunologically intact controls, and hepatocytes of infected deprived mice were not damaged in the absence of granuloma formation. S. ma/wow'‐infected deprived mice, however, die earlier than intact controls, and surfer extensive hepatocellular abnormalities. A high degree of cross‐reactivity between S. bovis, S. haematobium and S. mansoni antibodies and antigens was noted in immunoprecipitation but a greater degree of homology between S. haematobium and S. bovis egg antigens was demonstrated by enzyme immunoassay (ELISA). S. haematobium and S. bovis thus resemble each other more closely than either resembles S. mansoni, and in view of the apparent antigenic similarities between S. haematobium and S. bovis and the relatively greater ease with which the S. bovis life‐cycle can be maintained in the laboratory, the animal parasite may be useful in providing material for further immunological studies of the human infection.
Analysis of Propionibacterium amis‐induced non‐specific immunity to Trypanosoma brucei in mice
Authors: BLACK S. J. , MURRAY M. , SHAPIRO S. Z. , KAMINSKY R. , BOROWY N. K. , MUSANGA R. , OTIENO‐OMONDI F.
Published: October 2007

Summary Mice treated with dead Propionibacterium acnes (previously called Corynebacterium parvum), up to 30 days before infection with any of three strains of Trypanosoma brucei, were more able to limit the level of first‐wave parasitaemia than untreated controls. Reduced parasitaemia was not due to enhanced phagocytosis of input parasites and was associated with a dramatic reduction in the proportion of multiplying T. brucei in the blood of treated as compared to control mice. For 4 days after P. acnes treatment, T. brucei growth‐inhibitory molecules, assayed by their effect on T. brucei multiplication under axenic culture conditions, were detected in the serum of recipient mice. The molecules were released by macrophages collected from the peritoneal cavity of P. ac/ies‐treated mice, and similar molecules were produced in vitro by macrophages from normal mice after incubation with P. acnes. Accessory studies suggested that the molecules were breakdown products of P. acnes and were unlikely to be responsible for the long‐term in‐vivo effects of the P. acnes treatment. It was also shown that monokines and lymphokines which are likely to be induced by in‐vivo P. acnes treatment, i.e. IL‐1, IL‐2, TNFα, INFα, INFβ, INFy, PGE1, PGE2, PGF2, and biological mediators present in Con‐A and LPS‐induced spleen cell supernatants (collected 20, 40, 60 or 80 h after mitogen stimulation) had no influence on T. brucei growth under axenic culture conditions over a wide range of concentrations. The studies suggest that the P. acnes effect was not due to a direct interaction of these biological mediators with the T. brucei. We suggest that the reduction in T. brucei parasitaemia in P. acnes‐treated mice reflects secondary physiological effects of one or more unidentified biological mediators.
Parasite–specific T cell responses of sheep following live infection with the gastric nematode Haemonchus contortus
Authors: HAIG D. M. , WINDON R. , BLACKIE W. , BROWN D. , SMITH W. D.
Published: October 2007

Summary Helper T cell lines recognizing antigen in the context of MHC Class II molecules were generated from peripheral blood mononuclear cells (PBMC) of sheep undergoing a primary or secondary infection with the nematode parasite Haemonchus contortus. The lines were used to identify 15–18, 25–29, 70–80 and > 100 kD immunodominant parasite larval antigens fractionated by SDS–PAGE under reducing conditions. Non–specific mitogenic activity in the antigen fractions was not detected. During primary infection PBMC did not respond to soluble antigens or those fractionated on SDS–PAGE, whereas T cell lines generated from these PBMC responded well. T cell lines and PBMC derived after a secondary infection responded similarly to fractionated larval antigen. This indicated that (a) the T cell lines had retained their antigen specificities (as represented by autologous PBMC reactivity) in spite of in–vitro cycles of restimulation with whole larval soluble antigen and subsequent expansion in recombinant human IL–2, and (b) proliferation of the antigen–specific PBMC was predominantly due to helper T cells. Variations between individual sheep in response to fractionated larval antigens was also observed. The pattern of helper T cell reactivity to SDS–PAGE larval antigens correlated poorly with B cell reactivity in the same animals by serum antibody Western blot analysis. These results demonstrate that helper T cell epitopes can be mapped in complex parasite antigen preparations in sheep and that this approach will be useful in the identification of parasite protective antigens in helminthiasis where the cellular or humoral nature of protection is not clearly defined.
Role of mononuclear phagocytes in elimination of Plasmodium chabaudi AS infection
Authors: STEVENSON MARY M. , GHADIRIAN ESFANDIAR , PHILLIPS NIGEL C. , RAE DARLENE , PODOBA JOHN E.
Published: October 2007

Summary The role of mononuclear phagocytes in acquired immunity resulting in the intraerythrocytic destruction and elimination of malarial parasites was investigated in the murine model of infection with Plasmodium chabaudi AS. Mice were treated 1 day before or 6 days after infection with agents which either result in augmentation or activation of the non–specific, microbicidal effector function of mononuclear phagocytes or in depletion of cells of this lineage. To examine the effect of agents which activate mononuclear phagocytes, A/J mice, which are susceptible to P. chabaudi AS and exhibit fulminant parasitaemia and death within 10 days of intraperitoneal infection with 106 P–RBC, were treated intravenously with muramyl dipeptide (MDP) or liposome–encapsulated MDP–glycerol dipalmitate (MDP–GDP). Treatment administered 1 day before infection was ineffective. Treatment on day 6 post–infection with liposome–encapsulated MDP–GDP (1 ftg) resulted in a significant decrease in parasitaemia on day 8 and survival, while treatment with free MDP (100 ^g) resulted only in a significant decrease in parasitaemia. To examine the effect of depletion of mononuclear phagocytes, C57BL/6 mice, which are resistant to P. chabaudi AS infection and eliminate the parasite by 4 weeks, were treated intravenously with 3 mg silica. Silica administered 1 day before or 6 days post–infection abrogated resistance resulting in a delay in elimination of the parasite and host mortality. Treatment on day 6 was more effective, with death by day 13 post–infection of 70% of the normally resistant C57BL/6 mice which exhibited fulminant parasitaemia levels. These results thus provide in–vivo evidence that mononuclear phagocytes play a critical role in the elimination of infection with the murine malaria species P. chabaudi AS. Furthermore, these results suggest that the time of administration of agents which alter mononuclear phagocyte function may be important in determining their effect on host antimalarial defences.
Differential response of bovine T–cell lines to membrane and soluble antigens of Theileria parva schizont–infected cells
Authors: BROWN WENDY C. , SUGIMOTO CHIHIRO , CONRAD PATRICIA A. , GRAB DENNIS J.
Published: October 2007

Summary T–cell lines generated from Theileria parva–immunc cattle were used to identify antigens associated with schizont–infected lymphoblastoid cells. Homo–genates prepared from T. parua–infected cells were fractionated by differential centrifugation, and antigenically distinct soluble and membrane–bound antigens were detected by the differential stimulation of cell lines derived from two animals. Activity in the soluble fraction was not attributable to either a mitogen or interleukin 2. Activity in the membrane fraction was associated with schizont membranes as indicated by the presence in this fraction of a parasite protein detected by immunoblot analysis using a schizont–specific monoclonal antibody. Elimination of intracellular schizonts over time, using the anti–theilerial drug, parvaquone, resulted in a concomitant loss of antigenicity in infected cells and in subcellular fractions prepared from drug–treated cells, demonstrating that stimulation of Theileria–sptahc helper and cytotoxic T–cell responses is associated with the presence of the parasite.
Secreted antigens of filarial nematodes: a survey and characterization of in vitro excreted/secreted products of adult Brugia malayi
Authors: KWAN–LIM G. E. , GREGORY W. F. , SELKIRK M. E. , PARTONO F. , MAIZELS R. M.
Published: October 2007

Summary We report here a broad analysis of the excretory/secretory (E/S) products of adult Brugia malayi, collected by in–vitro cultivation of the parasite. Culture media and conditions were optimized, and non–essential amino acids were found to be crucial for efficient protein synthesis under cell– and serum–free culture conditions. A close correlation was found between total protein secretion, phosphorylcholine–bearing antigen release and lactate production on each day of culture, indicating that E/S molecules are actively secreted. Parasites cultured in vitro take 2–3 days to adjust to the new environment, and show peak levels of secretion at days 3 and 4. The active secretion of phosphorylcholine by the parasite therefore justifies the measurement of this molecule as an indication of active infection, possibly reflecting total worm burdens. By comparing metaboli–cally labelled E/S from male and female worms, several molecules of low mol. wt, namely 10000, 13000, 14 000 and 22 000, together with high mol. wt components of above 12000 were found to be female specific. Tracing the origin of the E/S products, several molecules were also found to be associated with the surface. Among these, there are at least two glycoproteins, 29 000 and 51000 of which the 29000 molecule is a major surface protein. The immunogenicity of the E/S was examined and antigenic cross–reactivity was found with sera from most filarial infections but not with non–filarial nematodiases such as hookworm or Trichi–. nella. However, two molecules of low mol. wt, 15 000 and 19000, were not recognized by anti–Onchocerca sera and appeared to be potential Brugia–specific diagnostic molecules. Possible functional roles of the adult E/S products were examined but we could find no evidence of protease activity in the E/S or glutathione S–transferase activity in either the E/S or in whole somatic extract.
Human and murine macrophages produce TNF in response to soluble antigens of Plasmodium falciparum
Authors: TAVERNE J. , BATE C.A.W. , SARKAR D.A. , MEAGER A. , ROOK G.A.W. , PLAYFAIR J.H.L.
Published: October 2007

Summary Heat‐stable antigens of rodent malarial parasites induce the release of tumour necrosis factor (TNF) from mouse macrophages, in vitro and in vivo. We report here that analogous antigens of Plasmodium falciparum trigger the release of TNF from human monocytes in vitro, in conditions that exclude the effects of any contaminating endotoxin. These antigens also induced TNF release from a murine monocytic cell line and from the peritoneal macrophages of several strains of mice, including the LPS‐hyporesponsive C3H/HeJ mice. Similarly, boiled soluble antigens from the rodent parasites P. yoelii and P. berghei also stimulated human monocytes. Antisera made by immunizing mice with boiled antigens of P. falciparum or P. yoelii inhibited the stimulation of TNF secretion by P. falciparum antigens. They did not block the induction of TNF by bacterial lipopolysacchar‐ide. Thus mouse macrophages provide a convenient system for investigating the nature, cross‐reactions and antigenic variation of human malarial soluble antigens. Since these are known to occur in the circulation of patients with malaria, they may be responsible for excess production of TNF, a mediator that is thought to play a central role in the pathogenesis of the disease.
Relationships between sequestration, antigenic variation and chronic parasitism in Plasmodium chabaudi chabaudi– a rodent malaria model
Authors: GILKS CHARLES F. , WALLIKER DAVID , NEWBOLD CHRIS I.
Published: October 2007

Summary We describe here a rodent malaria model using cloned lines of Plasmodium chabaudi chabaudi in inbred CBA/Ca mice that exhibits both clonal antigenic variation in late stage‐specific surface antigens, and deep vascular schizogony in the liver. We show that both these features are modulated by the spleen, and that surface antigen expression is crucially involved in the sequestering phenotype. Surface antigens are variant in chronic infection, and host protective immune responses can distinguish between these variants. Splenectomy abolishes this difference. The acute infection with non‐sequestering cloned lines is kinetically indistinguishable from sequestering clones, but parasites unable to express variant sequestration‐associated antigen do not form a chronic recrudescing infection. Another clone, able to re‐express this antigen in the presence of the spleen, undergoes typical chronic recrudescence. In this model, the biological significance of sequestration‐associated variant antigen seems to enable the establishment of chronic infection in the presence of a primed spleen.