bluuebunny/crossref_metadata_2025 huggingface dataset:
An antigen detection enzyme immunoassay for the diagnosis of rhodesiense sleeping sickness
Authors: NANTULYA V. M.
Published: October 2007

Summary A monoclonal antibody raised against a non–variable surface antigen of Trypanosoma brucei rhodesiense procyclic trypomastigotes was used to develop an antigen detection enzyme immunoassay for the diagnosis of rhodesiense sleeping sickness. The assay was evaluated using 211 sera from clinically suspected cases: 142 from parasitologically proven cases and 69 from patients who were negative on parasitological examination. The test was positive in 128 out of 142 parasitologically proven cases. The negative cases may have been in the early stages of the disease, or may represent patients with antibody levels sufficient to prevent detection of antigen. Of particular significance, however, was the finding that eight of the 69 patients with undiagnosed disease were antigen positive despite the negative parasitological findings. Since false–positive reactions were not observed with blood donor sera, or with sera from malaria, schistosomiasis and leishmaniasis patients, it is reasonable to conclude that the eight antigen–positive patients were actual cases of sleeping sickness. The remaining 61 cases who were negative for both parasitaemia and antigenaemia may conceivably represent the variety of diseases whose clinical manifestations resemble those of rhodesiense sleeping sickness. The antigen detection method would thus not only be complementary to parasitological diagnosis, but essential for correct diagnosis in certain stages of the disease.
Cytotoxic effects in vitro of human monocytes and macrophages on schistosomula of Schistosoma mansoni
Authors: COTTRELL BARRIE , PYE CAROLE , BUTTERWORTH ANTHONY
Published: October 2007

Summary Human peripheral blood monocytes from normal donors were isolated by differential centrifugation and cultured in vitro in hydrophobic Teflon–coated tissue culture bags. Cells were harvested between 0 and 10 days and tested for their ability to kill schistosomula of Schistosoma mansoni in an in–vitro cytotoxicity assay. Freshly isolated, unstimulated monocytes demonstrated minimal cytotoxic capability. However, this was increased if the cells were pretreated with human recombinant gamma interferon (IFN–γ), or with specific anti–5. mansoni antiserum. As the monocytes matured in vitro there were marked increases in the levels of antibody–independent killing of schistosomula. Monocytes grown in vitro with IFN–γ (104 u/ml) took 2–3 days to develop almost maximal cytotoxicity (mean 94% kill of schistosomula). In contrast, unstimulated monocytes (no IFN–γ) took between 5 and 7 days to achieve comparable cytotoxicity (mean 99% kill). Killing of the schistosomula was dependent upon a high effector to target ratio, and was a relatively slow phenomenon in vitro, parasite attrition occurring between 17 and 36 h. Supernatants from cytotoxic macrophages were ineffective in mediating cytotoxicity of the parasite.
The effect of antioxidants on the rejection of Nippostrongylus brasiliensis
Authors: SMITH N. C. , BRYANT C.
Published: October 2007

Summary The effect of the antioxidants, butylated hydroxy anisole (BHA) and vitamin E, on the rejection of Nippostrongylus brasiliensis from the small intestine of the rat was investigated. Worm expulsion was inhibited by BHA. Malonyldial–dehyde production in the small intestines and free radical generation by peritoneal leucocytes from infected rats were also inhibited by BHA. Vitamin E, although inhibiting malonyldialdehyde production, did not prevent worm expulsion. Significantly, vitamin E was much less effective than BHA at reducing free radical generation by rat leucocytes in response to N. brasiliensis.
Protective and pathological activity in serum of mice developing resistance toPlasmodium bergheiinfection
Authors: SCHETTERS T. P. M. , BREDA J. H. J. VAN RUN‐VAN , HERMSEN C. , CURFS J. , ELING W. M. C.
Published: October 2007

SummaryThe serum from mice developing resistance againstPlasmodium bergheiinfection using chemotherapeutic treatment has been analysedin vivoandin vitro.During the immunization period pathological as well as protective activities which could be transferred by serum were generated. The pathological activity, which was defined as destruction of erythrocytes in normal recipient mice, was generated early in the immunization procedure, peaked at day 21, and decreased to undetectable levels by day 35. After reinfection of the donor mice the pathological activity reappeared in the serum, and was maintained for at least 56 days. Analysis of the transferred serum samples showed the presence of anti‐erythrocyte antibodies (ELISA), but no correlation with the in‐vivo anti‐erythrocyte effect could be found. The anti‐erythrocyte effect of the serum samples indirectly increased the parasitaemia in the recipient mice through the induction of reticulocytosis. The protective effect of the serum samples could only be detected in samples taken from animals beyond day 61 of the immunization procedure. This net protective effect was reflected in a decreased parasitaemia at 7 days after challenge of the recipient mice withP. bergheiinfected erythrocytes. The protective activity of the serum was correlated with high titres of anti‐erythrocyte antibodies. Anti‐erythrocyte antibody titres were strongly correlated with titres against heterologous red blood cells as well as total immunoglobulin content of the serum samples, indicative of polyclonal activation of lymphocytes. Except for IgGl, all (sub‐) classes were elevated during the immunization procedure, of which IgG3 was abundant. After immunity was obtained these immunoglobulin levels remained high, and the relative amount of IgGl in the serum was restored.
Stage–specific antigens of Hymenolepis microstoma recognized in BALB/c mice
Authors: ITO AKIRA , ITOH MAKOTO , ANDREASSEN JØRN , ONITAKE KAZUO
Published: October 2007

Summary Antigenicity of eggs (oncospheres), cysticercoids and adults (with immature segments only) of the bile duct tapeworm Hymenolepis microstoma was analysed using immunoblotting techniques and indirect immunofluorescent antibody (IFA) techniques with immune sera of BALB/c mice (i) infected with different doses of cysticercoids, (ii) during patent or prepatent infection with the lumen phase of the parasite or (iii) sensitized with live or dead eggs. Antibody responses detected by IFA test and immunoblotting showed that antigenicity of eggs (oncospheres) differed from that of cysticercoids and adults. Single worm infections were sufficient to stimulate antibody responses. Mice which had patent infection showed strong antibody responses to all three (egg (oncosphere), cysticercoid, adult) antigens, while mice given two prepatent infections showed some antibody responses to cysticercoid and adult antigens only. Although the normal intermediate hosts of this parasite are arthropods, antibodies to some major egg (oncosphere) antigens were produced in mice given eggs of this parasite orally, either through inoculation of eggs or ingestion of faeces contaminated with eggs. Antibodies were not produced in mice dosed with non–viable eggs. The results are consistent with the hypothesis that cestode parasites express phase– (or stage–) specific antigens.
Localization and immunogenicity of tubulin in the filarial nematodes Brugia malayi and B. pahangi
Authors: HELM R. , SELKIRK M. E. , BRADLEY J. E. , BURNS R. G. , HAMILTON A. J. , CROFT S. , MAIZELS R. M.
Published: October 2007

Summary Tubulin was identified in the filarial nematodes Brugia malayi and B. pahangi by several approaches. Initially, a monoclonal antibody (6D8) was selected for its unusual binding to B. malayi microfilariae in indirect immunofluorescence assays: 6D8 showed granular, heterogeneously dispersed fluorescence on fixed parasites but did not bind to unfixed microfilariae. The microfilarial sheath did not bind 6D8, although it did bind fluoresceinated wheatgerm agglutinin. By Western blotting against microfilarial sonicate, 6D8 reacted with a 50000–55000 mol. wt protein, and also bound to purified chicken brain β–tubulin. Additionally, this monoclonal antibody reacted with a recombinant fusion protein expressed by a clone (Bpa–7) originally isolated from an adult B. pahangi cDNA expression library by its reaction with chronic human filariasis serum. This clone encodes a small 40 amino acid C–terminal segment corresponding to residues 409–449 of β–tubulin, and shows complete amino acid sequence homology with vertebrate β–tubulin from 409 to 430 but 55% divergence (six amino acid substitutions, four insertions and one deletion) from human and chicken β–tubulin over positions 431–449 at the C terminus. Antibody to both parasite and vertebrate (chicken) tubulin was found in filarial infection sera, with higher levels of autoreactive antibody apparent in amicrofilaraemic individuals. Immunogold electron microscopy was then used to localize β–tubulin in B. malayi microfilariae and adult worms. Tubulin was shown not to be exposed on the microfilarial sheath or in the cuticle of either stage, but was found to be abundant in the somatic tissues. In microfilariae, 6D8 bound myofibril structures under the hypodermal layer, and also bound within cell nuclei. In the adult stage, tubulin was associated with muscle blocks, as well as the intestinal brush border and the embryonic uterine microfilariae.
Pulmonary inflammation in parasitic infection: immunoglobulins in bronchoalveolar washings of rats infected with Nippostrongylus brasiliensis
Authors: RAMASWAMY K. , BEFUS D.
Published: October 2007

Summary Despite marked pulmonary pathology caused by larval stages of many helminth parasites, little is known about the mechanisms of immune and inflammatory responses to parasites in the respiratory tract. Using bronchoalveolar lavage (BAL) we have retrieved soluble proteins and cells from the respiratory tract of rats given a primary or secondary infection with the nematode Nippostrongylus brasiliensis. Total amounts of different immunoglobulin classes and albumin in BAL fluids and serum were quantitated using an ELISA. Analysis of the cellular component showed an increase in alveolar macrophages, neutrophils, eosinophils and lymphocytes on different days post–infection similar to our earlier findings. A time course study revealed that the concentrations of total protein, albumin, IgG, IgA and IgM in BAL fluids of infected animals were increased from days 2 to 32 after a primary infection. The magnitude of this increase was higher following a challenge infection (secondary) with the same parasite. Moreover, there was also a biphasic increase in total protein, IgG and IgA after secondary infections, with peaks on days 2 to 4 and 11 to 21 postinfection. A comparison of immunoglobulin to albumin ratios in serum and BAL fluids showed that the initial peak of proteins in the lavage was a result of serum leakage and the subsequent peak was due to local secretion of immunoglobulins. These results suggest that in addition to marked BAL cellular reactivity, N. brasiliensis infection induces an initial vascular and endothelial permeability in the respiratory tract which is soon repaired but followed by local synthesis and secretion of IgG and IgA in the lower respiratory tract.
Consecutive determinations of seroreactivities to Pf 155/RESA antigen and to its different repetitive sequences in adult men from a holoendemic area of Liberia
Authors: BJÖRKMAN A. , PERLMANN H. , PETERSEN E. , HOGH B. , LEBBAD M. , WARSAME M. , HANSON A.P. , PERLMANN P.
Published: October 2007

Summary Sera from 32 adult men residing in a malaria holoendemic area of Liberia were investigated for seroreactivities to different asexual blood‐stage malaria antigens on five consecutive occasions from 1984 to 1986. The seroreactivities to crude parasitic antigens and to Pf 155/RESA (EMIF) were determined by immunofluorescence and to repetitive sequences of Pf 155/RESA by enzyme‐linked immunosorbent assay (ELISA). All sera were highly reactive against the crude parasitic antigens with reciprocal titres varying from 5000 to 100000. The EMIF titres showed a wider variation from negative (< 10) to 25000, and when the same individuals were re‐examined on subsequent surveys similar EMIF titres were found. The ELISA seroreactivities to three different repetitive sequences of Pf 155/RESA also showed different individual profiles which were rather consistent on consecutive surveys. High EMIF titres appeared to be correlated mainly to one of the peptide sequences, namely (EENV)2. The consistent individual profiles of the seroreactivities to Pf 155 and its repetitive sequences suggest genetic restriction of the humoral immune response. Although no significant correlation was found between EMIF titres and parasitic densities in the adult hyperimmune men the specific peptides, however, offer new possibilities of further investigating protective capacities of different immune responses to specific epitopes of the malaria parasite.
Stage‐specific immunity to Taenia taeniaeformis infection in mice. A histological study of the course of infection in mice vaccinated with either oncosphere or metacestode antigens
Authors: BØGH HENRIK O. , LIGHTOWLERS MARSHALL W. , SULLIVAN NEILL D. , MITCHELL GRAHAM F. , RICKARD MICHAEL D.
Published: October 2007

Summary The course of Taenia taeniaeformis infection in mice previously vaccinated with antigens prepared from either oncosphere (TtO) or metacestode (TtM) was followed by histological examination of livers from mice killed at various times post‐infection (p.i.). Distinctly different immune responses occurred in the two groups. Very few cysts were seen at any stage of infection in TtO‐vaccinated mice and most of those which were present appeared histologically similar to cysts in control mice. In TtM‐vaccinated mice many cysts were present from early in infection but histologically it was apparent that most were dying from 15 days p.i. because the tegument had lost its integrity, and degranulated polymorphonuclear leucocytes were present inside the parasites. These findings support earlier suggestions that stage‐specific antigens are expressed in oncospheres and metacestodes. Parasites developing normally were surrounded by a halo of alcian blue staining amorphous acellular material. This material appeared to act as a barrier to attack by host inflammatory cells, and disappearance of this layer signalled death of the parasite. The possibility that the gut acted as a barrier to delay migration of oncospheres to the liver in vaccinated mice was investigated, but no evidence for this could be found.
Antigenicity of adult Schistosoma mansoni alkaline phosphatase
Authors: PUJOL F.H. , CESARI I.M.
Published: October 2007

Summary Antibodies to the alkaline phosphatase (AP) of Schistosoma mansoni in infected human and mice sera were evaluated by a direct solid‐phase AP immunoadsorption assay (APIA) and by Western blot and immunostaining. APIA consisted of (a) solid‐phase capture of immunoglobulins from infected human or mice, (b) immunoadsorption of the enzyme antigen by the antibodies, and (c) detection of the enzymatic activity. By this procedure the appearance of the anti‐AP response in mice was detected around 50 days post‐infection; this response was not specific for an AP of a given schistosome strain and it was not induced by an autoimmunity phenomenon. Fourteen out of 15 sera from infected people tested by APIA showed a clear antibody response against this enzyme. Immunoblots in non‐reducing conditions supported APIA results indicating that the parasite AP was specifically recognized by the antibodies present in infected human and mice sera. These results suggest the possible usefulness of the schistosome AP as a marker for S. mansoni infection.
Immune dependence of schistosomicidal chemotherapy: an ultrastructural study of Schistosoma mansoni adult worms exposed to praziquantel and immune serum in vivo
Authors: MODHA J. , LAMBERTUCCI J.R. , DOENHOFF M.J. , McLAREN DIANE J.
Published: October 2007

Summary This study examines the immune‐dependence of praziquantel (PZQ) for the treatment of Schistosomiasis mansoni in mice. We have shown elsewhere from worm recovery data that the efficacy of PZQ is significantly enhanced when mice are treated concomitantly with antisera raised against antigens released from adult schistosomes, even though such antisera show no intrinsic helminthotoxic activity (Doenhoff et al. 1987, DoenhofT, Modha & Lambertucci 1988). Moreover, indirect immunofluorescence assays have shown that male worms exposed to the dual treatment regime in vivo bind antiserum to their dorsal surfaces in a pattern that seems to follow the outline of the dorsal tubercles. Scanning and transmission electron microscopy have now been used to further define the features of damage inflicted upon worms through exposure to antiserum alone, drug alone, or the two treatments in combination. Such investigations revealed that the antiserum induces a classical membrane repair process in worms of both sexes, but little other damage. PZQ causes the formation of spherical protuberances on the dorsal tubercles of male worms, while the dual treatment regime induces both kinds of damage in male schistosomes, but with much enhanced severity. The protuberances show evidence of explosion and some regions of the tegument become completely destroyed.

Regions other than the dorsal surfaces of the male worms do not exhibit comparable trauma, and neither do the females. These data are discussed in relation to the known schistosomicidal activity of PZQ, the notion that male and female worms exhibit regional and sexual differences in susceptibility, documerited evasive strategies of the parasite and the interdependence of immuno‐ and chemotherapy.
Serum antibody specificities to Leishmania aethiopica antigens in patients with localized and diffuse cutaneous leishmaniasis
Authors: MENGISTU G. , AKUFFO H.O. , YEMANE‐BERHAN T. , BRITTON S. , FEHNIGER T.E.
Published: October 2007

Summary In order to characterize the antigenic determinants of Leishmania aethiopica, we have analysed by immunoblotting the antibody reactivity of leishmaniasis patients with either the localized (LCL) or diffuse (DCL) clinical forms of disease. In this study we have compared the reactivity of antibodies from eight LCL and DCL patients to parasites isolated from each individual, or the parasite isolates of the other LCL and DCL patients studied. The immunoblot profiles of antibodies from LCL patients differed from the antibody profiles of DCL patients. Serum antibodies from LCL patients showed limited recognition of somatic antigens of < Mr 50000 which were recognized by antibodies present in DCL patients. A direct comparison of individual LCL and DCL patient derived promastigotes determined that the lack of antibody to these antigens in LCL patients was not due to the differential expression of these determinants by the LCL and DCL derived promastigotes. The results of this study suggest that although either LCL or DCL derived promastigotes express a wide variety of antigenic moieties which are potentially reactive with antibodies, only a subset of antibodies against these specificities develop in any individual patient, during active infection.
Functional correlations between mucosal mast cell activity and immunity to Trichinella spiralis in high and low responder mice
Authors: TUOHY M. , LAMMAS D. A. , WAKELIN D. , HUNTLEY J. F. , NEWLANDS G. F. J. , MILLER H. R. P.
Published: October 2007

Summary Levels of intestinal mast cell protease (IMCP) were quantified in serum, gut tissue and in intestinal fluids taken from mice infected with Trichinella spiralis during primary and secondary infections. The ability to generate a mast cell response was dependent on the response phenotype of the mouse strain used. The mast cell response in rapid responder mice (NIH) occurred sooner and was more pronounced than in either intermediate (SWR) and low responder (BIO) mice. This pattern was also reflected in the concentration of IMCP found in various tissues examined. The correlations between IMCP concentrations in blood, and worm expulsion, are discussed.
Tegumental surface modulation in Schistosoma mansoni primary sporocysts in response to ligand binding
Authors: DUNN TERRY S. , YOSHINO TIMOTHY P.
Published: October 2007

Summary The clearance of host molecules from the surface of a parasite constitutes a potential immune evasive strategy. The possibility that certain ligands. when bound to the tegument of Schistosoma mansoni primary sporocysts, could induce such a modulating effect was investigated. Live, in vitro cultured primary sporocysts were first treated with either snail host Biomphataria glabrata plasma, an anti‐sporocyst monoclonal antibody (MoAb III‐1), or concanavalin A (con A). The capacity of these primary ligands to produce a modulating effect alone, or when subsequently crosslinked by secondary or tertiary ligands, was measured using quantitative fluorescence microscopy. Snail plasma alone, or plasma crosslinked at the sporocyst surface with a mouse anti‐plasma MoAb had little or no modulating effect. However, a tertiary level of ligand crosslinking with an anti‐mouse IgG antibody produced an average 1.8‐fold decrease in surface fluorescence within 1 h post‐labelling. The anti‐sporocyst MoAb III‐1 also required secondary antibody reactivity to induce an average 1.5‐fold decrease in MoAb III‐1 recognized epitopes. Sporocysts labelled wilh con A crosslinkcd by secondary and tertiary ligands showed inconsistent modulation, with a 1.5‐fold decrease in fluorescence in one out of three replicates. Overall, however, analysis of combined data revealed no significant effect of tertiary ligand level crosslinkage on modulation of con A‐tegumental receptor complexes. In contrast, con A binding alone to tegumental determinants induced a small, but significant, reduction in surface con A complexes. Modulation of ligand‐receptor complexes on the sporocyst tegumental membrane appears to be an energy‐requiring event, since clearance of surface complexes was inhibited in the presence of sodium azidc and/or sodium iodoacetate, or when larvae were incubated at 4°C. It is concluded that alterations in sporocysl tegumenlal surface components may be triggered by specific (but as yet undefined) signals. Sporocysts are capable of exhibiting different responses depending on the nature of the binding signal and reactive tegumental receptor, and the degree of ligand crosslinkage.
Analysis of peripheral leucocyte populations in N'Dama and Boran cattle following a rechallenge infection with Trypanosoma congolense
Authors: WILLIAMS D.J.L. , NAESSENS J. , SCOTT J.R. , McODIMBA F.A.
Published: October 2007

Summary Monoclonal antibodies, flow cytometry and routine hacmatological techniques were used to analyse circulating leucocyte populations in trypanotoler‐ant (N'Dama) and trypanosusceptible (Boran) cattle following a homologous rechallenge with Trypanosoma congolense clone 1L13‐E3. The N'Damas developed a low, transient parasitaemia and did not develop anaemia. The Borans became parasitaemic and developed chronic anaemia but three of the five animals eventually self‐cured, whilst, a group of primary‐challenged Borans experienced a severe infection characterized by high levels of parasilacmia and acute anaemia.

During infection the numbers of circulating B‐cells increased in all three groups from day 21 onwards. The proportion of B‐cells expressing the CD5 antigen increased from pre‐infection levels of 5‐10% of B‐cells to 49‐90% by day 19 post infection in all three groups. The neutrophil count declined in both Boran groups but not in the N'Damas. The CD4+ T‐cell and γδ T‐cell populations decreased in both Boran groups but did not alter significantly in the N'Damas. Although it was not possible to infer from the data, that the CD4+, γδ T‐cell, neutrophil and erythrocyte populations were directly responsible for the differential control of the disease by the two breeds, it was possible to correlate alterations in these cell populations with the severity of the disease.
The role of immunoglobulin and complement in enhancing the respiratory burst of neutrophils against Trichomonas vaginalis
Authors: SHAIO M.F. , CHANG F.Y. , HOU S.C. , LEE C.S. , LIN P.R.
Published: October 2007

Summary Human neutrophils. alone, did not kill Trichomonas vaginalis. More than 90% of T. vaginalis (105/ml) survived in the presence of 10% normal human serum (NHS) while 90% of these organisms were killed in the presence of a combination of neutrophils (106/ml) and 10% NHS. Mechanisms responsible for this serum‐mediated neutrophil killing of T. vaginalis were demonstrated through a process of lucigenin‐amplified neutrophil chemiluminescence. As evidenced by indirect immunonuores‐cence, NHS showed specific immunoglobulin G (IgG) titre of 1:8 for T. vaginalis. Purified IgG, at 1.6 mg/ml, showed no direct opsonizing or lytic effect on ibis organism. Formalin‐fixed trichomonads opsonized by C2 deficient human serum promote 4 times more neutrophil chemiluminescence than those opsonized by Factor B deficient human serum. With the addition of purified IgG (5 mg/ml) neutrophil chemiluminescence was increased by 4 times and further improved trichomonal killing by neutrophils (from 5 ± 4% to 78 ± 16%) via activation of the classical complement pathway, but did not alter that due to activation of the alternative complement pathway. These studies indicate that both an IgG‐enhanced classical complement pathway activation and an antibody‐independent alternative complement pathway activation provide opsonin (C3) for T. vaginalis to facilitate the neutrophil killing mechanism.
MHC‐restriction of antibody responses to an 86 kilodalton antigen of Schistosoma mansoni
Authors: SCHWEITZER A. NICOLA , TAYLOR DAVID W.
Published: October 2007

Summary The previously observed MHC‐restriction of the antibody response to an 86kDa S. mansoni antigen has been investigated in more detail. The I‐A locus of the H‐2 complex has been implicated as conferring responder or non‐responder status on mice expressing the k and b alleles respectively. Inheritance of responsiveness was dominant over non‐responsiveness. An additional level of complexity was observed in the p86 antibody responder status of individuals within a responding inbred strain. This could not be accounted for directly by the level of patent infection, but showed an inverse correlation with the level of egg output in H‐2k mice. Differential antibody responsiveness to other antigens, between individuals of the same strain, occurred independently of the differential responsiveness to p86.
Genetic studies on a major merozoite surface antigen of the malaria parasite of rodents, Plasmodium chabaudi
Authors: McLEAN ANN P. , LAINSON F.ALEXANDER , MSHARKEY ANDREW , WALLKER DAVID
Published: October 2007

Summary Diversity in a major merozoite surface antigen (MSA‐1) of plasmodium chabaudi has been examined using a panel of monochlonal antibodies (MoAbs). The antigen was found to be different in each of twelve cloned isolates, as shown by its reactivity with the MoAbs in immunofluorescence tests. In genetic crossing experiments, the diverse forms of this antigen were shown to be determine by allelic variation of a single gene. Recombination occurred between the MSA‐1 gene, a second blood stage antigen and enzyme markers.
Susceptibility of N'Dama and Boran cattle to sequential challenges with tsetse‐transmitted clones of Trypanosoma congolense
Authors: PALING R.W. , MOLOO S.K. , SCOTT J.R. , GETTINBY G. , MCODIMBA F.A. , MURRAY MAX
Published: October 2007

Summary The susceptibility of N'Dama cattle (Bos taurus) to four consecutive infections with different tsetse‐transmitted clones of Trypanosoma congolense was compared with that of Borans (Bos indicus). All animals were aged 13 months al the start of the study and had been born and raised free from trypanosomiasis under the same management and nutritional conditions, thereby limiting environmental factors that could have influenced susceptibility. While cattle of both breeds were equally susceptible to the establishment of trypanosome infections, the N'Damas exhibited superior resistance. Despite infection with virulent parasites, the N'Damas gained weight at the same rate as uninfected control animals, they did not develop anaemia to the extent that trypanocidal drug treatment was required, and all made a spontaneous recovery to normal hacmatological values within two to four months. In contrast, all the Borans needed treatment during the course of the four infections because of severe anaemia and showed markedly reduced liveweight gains. These clinical differences in the N'Damas were associated with two repcatable characteristics, namely, the ability to control parasitaemia and to‘resist’ anaemia, processes that did not appear to be linked. Also in contrast to the Borans. the N'Damas were able to mount accelerated haemopoietic responses, resulting in the reduced severity of anaemia following a primary infection. These findings pose the question as to whether the ability to control parasitaemia and to‘resist’ anaemia could be used as criteria for identifying resistant or trypanotolerant cattle.
The prophenoloxidase system and in vitro interaction of Trypanosoma rangeli with Rhodnius prolixus and Triatoma infestans haemolymph
Authors: GREGÓRIO ELISA A. , A.RATCLIFFE NORMAN
Published: October 2007

Summary The presence of the prophenoloxidase (proPO) system in the haemolymph of Rhodnius protixus and Triatoma infestans and the role played by Trypanosoma rangeli in the in vitro activation of proPO were tested. Both R. prolixus and T. infestans whole blood preparations showed a very active ProPO system. The proPO cascade of the two insect species were differentially activated by microbial‐derived extracts: laminarin was a better activator of T. infestans haemolymph than of R. prolixus blood, and lipopolysaccharides from Shigella flexneri or Pseudomonas aeroginasa caused significant proPO activation of T. infestans haemolymph but not of R. prolixus preparations. For the two insect species, neither T. rangeli from culture nor parasite lysates were able to trigger proPO activation. The presence of the parasite in R. prolixus haemolymph/laminarin assays, however, significantly reduced the level of proPO activation to that of spontaneous activating controls. The immobilization of T. rangeli in vitro in haemolymph preparations occurred in both insect species and was dependent on the proPO activation intensity Our results suggest that the susceptibility of R. prolixus to T. rangeli haemocoel infection may be explained, at least in part, by the suppression of the insect immune defence system i.e., inhibition of proPO in the presence of this protozoan parasite.
Antigenic variation in Giardia lamblia: infection of congenially athymic nude and scid mice
Authors: GOTTSTEIN BRUNO , E.NASH THEODORE
Published: October 2007

Summary Athymic nude mice of the outbred Zur:ICR‐nu and inbred BALB/c strain and scid mice were infected with a cloned human isolate of Giardia lamblia (GS M‐83‐H7). Changes in the expression of the major surface epilope of the intestinal trophozoites (characterized by the binding capacity of monoclonal antibody MoAbG 10/4) as well as cellular and humoral immune parameters of the hosts were followed during the course of infection. Self‐cure was observed in hetcrozygous (nu/+) BALB/c mice by day 22 post‐infection (p.i.) and in heterozygous (nu/+) Zur:ICR‐nu strain by day 65 p.i. Homozygous (nu/nu) mice of both strains remained chronically infected until end of the experiments (day 45 p.i. for BALB/c mice and day 122 p.i. for Zur:ICR‐nu mice, respectively). Only heterozygous (nu/+) mice were able to mount a gut‐associated (Peyer's patch) lymphoproliferative response to G. lamblia antigen. Therefore, T‐cell dependent mechanisms were necessary for a self‐cure. Antigenic variation occurred in all nu/+ and nu/nu animals of both strains. Trophozoiles expressing the major surface epitope (assessed by direct immunofluorescence with FITC‐labelled MoAb G10/ 4) decreased to zero by day 22 p.i. In contrast, the proportion of trophozoites expressing the major surface epitope in infected scid mice remained at the initial level (>99%) until termination of the experiment (day 25 p.i.); therefore, antigenie variation did not occur. All nu/nu and nu/+ mice but not scid mice demonstrated a humoral immune response to G. lamblia antigen. These experiments suggest functional B‐cell dependent mechanisms are most likely responsible for the surface antigen switch. Transfer of infection occurred naturally from experimentally infected scid‐mice to their mother, proving the initial antigenic surface variant remains unchanged after encystment and subsequent excystmenl followed by infection in a new host.
Epitopes of the Plasmodium falciparum clustered‐asparagine‐rich protein (CARP) recognized by human T‐cells and antibodies
Authors: WAHLGREN MATS , BEJARANO MARIA‐TERESA , TROYE‐BLOMBERG MARITA , PERLMANN PETER , RILEY ELEANOR , GREENWOOD BRIAN M. , PATARROYO MANUEL E. , GONZALES CLARA‐ISABEL , MARTINEZ ALBERTO
Published: October 2007

Summary Linear B‐ and T‐cell epitopes have been identified in the Plasmodium falciparum clustered‐asparagine‐rich‐protein (CARP). Twenty‐six synthetic peptides. 15‐25 amino acids in length, were assayed for their ability to stimulate purified, human T‐cells primed to P. falciparum by natural infection to proliferate and/or secrete y‐interferon (IFNy). The plasma of malaria exposed individuals were tested for antibody reacthiu with peptides coupled to bovine scrum albumin in a semiquantitative ELISA. Two of the peptides (NNFMNRNMKNKNMN/NAKNVNDMYRDGEMS) induced T‐cells from many malaria exposed donors to proliferate and/or secrete ‐IFNy. Six peptides bound antibodies from a large number of the plasma samples, the amounts ranging from ten to more than 200/ug specific antibody/ml. T‐cell activation was most pronounced when the T‐cells were from highly immune donors. In contrast, high anti‐peptide specific antibody levels were usually detected in the plasma of less immune donors, recently exposed to infection. One short sequence (NAKNVNDMYRDGEMS) was found to contain both T‐ and B‐cell epitopes. Thus, CARP includes both T‐ and B‐cell reactive elements recognised by the human immune system following exposure lo the parasite by natural infection.
Binding of antibody and resistance to lysis of trypomastigotes of Trypanosoma cruzi
Authors: JACOBSON KYM C. , FLETCHER ROBERT C. , KUHN RAYMOND E.
Published: October 2007

Summary Epimastigote forms of Trypanosoma cruzi are readily lysed by complement via the alternative pathway. Neither fibroblast‐derived trypomastigotes nor blood‐form trypomastigotes are lysed by complement alone and few (less than 30% of the Brazil strain) are lysed in the presence of parasite‐specific antibody and complement. The mechanism by which trypomastigotes resist antibody‐dependent, complement‐mediated lysis is not clearly understood. In the present study, we have utilized flow cytometric analysis to examine the binding of parasite‐specific antibody to epimastigotes, fibroblast‐derived trypomastigotes and blood‐form trypomastigotes of a Brazil strain of T. cruzi. We also determined the extent of lysis of these parasites in the presence of complement utilizing propidium iodide to determine cell death. It was found that all epimastigotes bind approximately the same amount of antibody but that there are subpopulations of trypomastigotes which bind antibody to varying degrees. When these subpopulations were sorted, and treated with complement, lysis was only minimally increased in the population of parasites which bound significantly greater amounts of antibody.
Anti‐circumsporozoite protein antibodies measure age related exposure to malaria in Kataragama, Sri Lanka
Authors: MENDIS CHANDANA , DEL GIUDICE GIUSEPPE , GAMAGE‐MENDIS ASOKA C. , TOUGNE CHANTAL , PESSI ANTONELLO , WEERASINGHE SUDATH , CARTER RICHARD , MENDIS KAMINI N.
Published: October 2007

Summary Antibodies to two peptides DDAAD and (NANP)40 representing the repetitive sequence of circumsporozoite antigens (CS protein) of P. vivax and P. falciparum respectively were measured in a cohort of 149 and 107 individuals respectively at four, 6 monthly blood surveys performed on residents of Kataragama, a P. vivax malaria endemic region in southern Sri Lanka. The prevalence of antibodies to the CS protein of both species was relatively low being less than 20% to either peptide in the population as a whole, this being consistent with the low entomological inoculation rates in the area. A marked age related prevalence pattern was evident, with the prevalence of antibodies increasing with age to reach between 25 to 30% in the 25–50 year age group in both P. vivax and P.falciparum. The population had had a life long exposure to P. vivax malaria but not to P.falciparum, an epidemic of which occurred in this region a few months prior to the beginning of this study. Nevertheless, the age‐related prevalence of these antibodies was identical with respect to the two species. This suggests that the age‐related prevalence pattern reflected differences in inoculation rates between the age groups due to differences in exposure to inoculation rather than an age acquired response resulting from a cumulative experience over several years. An analysis of antibody prevalence in individuals showed first, that sporozoite inoculations must have been clustered rather than homogeneously distributed in the population and secondly, that sero‐conversion did not correlate with malaria infections in these individuals.
In human malaria protective antibodies are directed mainly against the Lys‐Glu ion pair within the Lys‐Glu‐Lys motif of the synthetic vaccine SPf 66
Authors: MOLANO ALBERTO , SEGURA CESAR , GUZMAN FANNY , LOZADA DIANA , PATARROYO MANUEL ELKIN
Published: October 2007

Summary The KEK (Lysine‐Glutamic acid‐Lysine) motif is frequently found in the primary structure of certain malaria proteins involved in invasion, and plays an important role in the interaction of these proteins with the erythrocyte. This motif is contained in a peptide which forms part of the polymeric synthetic malaria vaccine SPf 66, currently undergoing extensive human trials. Analysis of the antibody titres against the subunit peptides that comprise this vaccine has shown that protection is associated with high titres to the KEK‐containing peptide. In this paper we examine the fine recognition of this motif by polyclonal sera from protected vaccinated individuals, demonstrating the critical role played by the interacting ion pair formed between the amino terminal lysine (K) and glutamic acid (E), which act as contact residues for an important proportion of the antibody population directed against this vaccine. This ion pair in the KEK motif constitutes perhaps one of the most important malaria epitopes involved in protection, and could explain the mechanism through which protective immunity is acquired.
Inhibition of protein synthesis in irradiated larvae of Schistosoma mansoni
Authors: WALES ANN , KUSEL JOHN R. , JONES JANET T.
Published: October 2007

Summary UV‐irradiated and gamma‐irradiated schistosomula of Schistosoma mansoni induce high levels of resistance to challenge infection in experimental hosts. It was observed that both types of irradiation severely inhibited protein synthesis by the parasite larvae. Schistosomula were treated with the metabolic inhibitor actinomycin D to simulate this effect of irradiation. The ability of these drug‐treated larvae to induce immunity was tested in animal protection experiments. Our results suggest that inhibition of protein synthesis may help to generate the enhanced immunogenicity of irradiated schistosomula. In explanation, we propose that irradiated schistosomula may be such potent immunogens because they express antigens in disrupted, abnormal conformations. Inhibition of protein synthesis may both directly create such modified antigens, and also ensure that they persist and accumulate for presentation to the host immune system.
Antibody‐dependent cell‐mediated immune reactions to Loa loa microfilariae in amicrofilaraemic subjects
Authors: PINDER MARGARET , LECLERC ANNICK , EVERAERE SIMONE
Published: October 2007

Summary Antibody‐mediated mechanisms that could be important in controlling microfilaraemia in Loa loa infected amicrofilaraemic adults (mf‐ve) were studied. These subjects were selected as having a verified ocular passage of an adult L. loa but being amicrofilaraemic and without recent diethylcarbamazine treatment. Sera from 37 mf‐ve subjects were compared to 14 sera from heavily (> 4000 mf/ml) infected subjects (mf+ve) and 9 sera from Caucasian control subjects for their reactions with L. loa mf (mf). Many mf‐ve sera (22/37) were strongly positive in immunofluorescence (IFAT) on living mf. Mf+ve sera were negative, or only weakly positive, and Caucasian sera were negative. Clinical signs were not significantly different between IFAT reactive and non‐reactive mf‐ve subjects. Approximately half of the IFAT positive, mf‐ve sera were also able to agglutinate mf: no other sera were active in this test. Titres ranged from log2 3–6 and in most cases, 9/11, the agglutination reaction was mercaptoethanol‐sensitive. Antibody‐dependent cellular adherence was studied using mf and leukocytes from uninfected donors. Using cryopreserved mf many heat‐inactivated mf‐ve sera gave strong reactions with obvious adherence by 4 h and few motile mf remained by 16 h but when fresh mf were employed these reactions were weak. However, addition of complement to many (10/11) mf‐ve sera considerably enhanced adherence to fresh mf. The effect of various treatments on the complement source indicated a role for both the classical and alternative pathways. The cells attached to mf were mainly neutrophils (83%) with some eosinophils (15%) and few mononuclear cells (2%). The common occurrence of antibodies able to mediate complement‐dependent adherence of polymorphonuc‐lear leukocytes to L. loa mf in the sera of mf‐ve subjects may indicate that such a mechanism is important in controlling microfilaraemia in vivo.
Immune response of Clun Forest sheep to vaccination with membrane glycoproteins from Haemonchus contortus
Authors: TAVERNOR ANGELA S. , SMITH TREVOR S. , LANGFORD CORDELIA F. , GRAHAM MARGARET , MUNN EDWARD A.
Published: October 2007

Summary Clun Forest lambs were injected with a fraction containing integral membrane glycoproteins derived from the intestinal microvilli of Haemonchus contortus in two equal doses of 0.5, 5, 50 or 500 μg protein and then challenged with 10 000 infective larvae. The time‐course of serum specific antibody responses were determined. Compared to the adjuvant control group, the animals injected with 1000 μg protein were better than 84% protected and those injected with 100 μg. better than 95% protected by all criteria. For these two groups parasite egg output was reduced 99% on average over the patent period. Two of the animals injected with 10 μg protein were partially protected, with 86% reduction in egg output. Two animals in the group injected with 1 μg protein also showed partial protection. Antibody level correlated with protection.
Standardization of a technique for analysing the frequency of parasite‐specific cytotoxic T lymphocyte precursors in cattle immunized with Theileria parva
Authors: TARACHA EVANS L. N. , GODDEERIS BRUNO M. , SCOTT JIM R. , MORRISON W. IVAN
Published: October 2007

Summary A limiting dilution microculture system was optimized to quantify the frequency of Theileria parva‐specific cytotoxic T lymphocyte precursors (CTLp) in peripheral blood mononuclear cells (PBMC) from immune cattle. Optimal results were obtained with responder cell input levels ranging from 2 × 104/well to 6.25 × 102/well, along with 1–5 × 103/well stimulator cells in standard supplemented RPMI 1640 medium containing 2.5–5% T cell growth factors. Thirty‐six microtitre wells were established at each responder input level. Cultures were incubated for 7 days at 38°C, at the end of which time individual wells were screened for cytotoxic activity in a 4‐h 111indium oxine‐release assay. Analysis of the cytotoxicity data, by a computer‐programmed maximum likelihood estimation method indicated that they conformed to the Poisson model of single‐hit kinetics. Estimates of frequencies ranged from 1:3600 to 1:5275 CTLp in PBMC of eight cattle between 1 and 24 months after immunization with T. parva. By contrast, no CTLp were detected in six naïve animals analysed to a responder cell input of 105/well. Split‐well analysis of individual microwells showed that the CTL clones generated under limiting dilution conditions displayed exquisite specificity for parasitized cells, were genetically restricted and in some animals were parasite strain‐specific.
In vitro lymphoproliferative responses to malaria antigens: a prospective study of residents of a holoendemic area with perennial malaria transmission
Authors: MSHANA R. N. , BOULANDI J. , MAYOMBO J. , MENDOME G.
Published: October 2007

A longitudinal, prospective study to examine the relationship between the outcome of infection with Plasmodium falciparum parasites and in vitro T‐cell proliferative responses to a P. falciparum schizont extract (PfSE) was conducted in a village in south‐eastern Gabon, an area where malaria is holoendemic and transmission is intense and perennial. The donor's age was found to have a strong independent influence on all malariometric indices. At the community level, the in vitro lymphoproliferative response to PfSE was bimodal with 30% of the villagers studied showing persistently low responses. The frequency of low or high responders within the study population did not show any consistent relationship with the community parasite rates or the number of either patent parasitaemic episodes or clinical malarial attacks per individual. At the individual donor level, the response was negatively correlated with P. falciparum parasite density in those donors who were parasitaemic at the time of sampling. High in vitro lymphoproliferative responses to PfSE were predictive of resistance to clinical malaria. The PfSE‐induced in vitro lymphoproliferative response was dependent on antigen presenting cells, CD4+ T‐cells and UCHL‐1+cells.
The in vivo role of stem cell factor (c‐kit ligand) on mastocytosis and host protective immunity to the intestinal nematode Trichinella spiralis in mice
Authors: GRENCIS R. K. , ELSE K. J. , HUNTLEY J. F. , NISHIKAWA S. I.
Published: October 2007

The role of stem cell factor (SCF) in the generation of intestinal mast cell hyperplasia and host protective immunity following helminth infection was investigated using the Trichinella spiralis/mouse model. In vivo administration of a monoclonal antibody specific for the receptor for SCF (c‐kit) was found to completely prevent the generation of intestinal mastocytosis normally observed following T. spiralis infection. This was reflected by markedly reduced intestinal mast cell protease (IMCP) levels in both tissue and serum. Moreover, animals treated with anti‐c‐kit antibody failed to show any evidence of worm expulsion from the gut. The data demonstrate for the first time, a critical role for the SCF in the generation of mucosal mastocytosis and host protective immunity following an intestinal helminth infection.
Schistosoma mansoni: genetic non‐response to p40, the major protein antigen of the egg, reveals a novel mechanism enhancing IgM production during infection
Authors: TRZYNA WENDY C. , CORDINGLEY JOHN S.
Published: October 2007

p40 is the major protein antigen in eggs and miracidia of Schistosoma mansoni. Immunization with recombinant p40 produced in bacteria and with p40 from miracidia reveals a conventional immune response gene effect in which H‐2b mice fail to produce antibody against p40. This is true when either denatured recombinant p40 and non‐denatured miracidial p40 are used as immunogens. In contrast, during infection all strains of mice produce antibodies to p40. However, non‐responder H‐2b mice produce only IgM to p40 and never any IgG. Thus, H‐2b mice appear to be producing specific IgM to p40 in the absence of MHC‐restricted T‐cell help. The mechanism revealed in these non‐responder mice might play an important role in stimulating the production of IgM ‘blocking’ antibodies to antigens from schistosomula which cross‐react with egg antigens.