Effect of T-activin on the course of experimental infection with Taenia crassiceps (Zeder, 1800) in mice

T-activin--an immunomodulating preparation of polypeptidic character prepared from calf thymus--was used for influencing the course of infection in a model system mouse-Taenia crassiceps. A single s.c. application of 100 micrograms of T-activin at various intervals before and after infection resulted in a marked decrease in the number of cysticerci in peritoneal cavities of experimental mice (by 47.1-93.6%) compared to the controls. After s.c. application of T-activin and i.p. injection of antigen (crude T. crassiceps larvae homogenate from mice) the decrease in the cystricercus number was still more pronounced than in the mouse groups receiving only T-activin or homogenate (by 76.9% in comparison with 65.5% and 17.0%, respectively). A combination of T-activin with crude T. crassiceps homogenate from rats did not produce the same effect in experimental mice. The protective effect of individual combinations of T-activin with the homogenate does not correlate with the antibody level in the serum of infected mice.     

Dependency of resistance of mice immunized against Taenia crassiceps on the dose of soluble antigen

Mice immunized with a single dose (1.25-40 micrograms/mouse) of soluble antigen from Taenia crassiceps cysticerci developed a 62.9-85.0% resistance. Maximum effect was achieved in the groups immunized with 40 micrograms and 20 micrograms of antigen. The dose of 5 micrograms induced the lowest number of successful infections (28.6%), but the mean number of surviving larvae was higher than in the above groups.     

Characteristics of malic enzyme from the cysticerci of Taenia crassiceps (Zeder, 1800)

Kinetic parameters of partly purified malic enzymes (NADP+: L-malate oxidoreductase (decarboxylating) EC 1.1.1.40) from the cytoplasm and mitochondria of Taenia crassiceps cysticerci were compared. The cytoplasmic malic enzyme differed from the mitochondrial malic enzyme in the K'M for malate; other studied properties were identical. The chromatographies of both the cytoplasmic and mitochondrial enzymes were identical. They exhibited a hyperbolic dependence of the activity on malate concentration, sigmoidal kinetics was not observed. The effects of succinate and fumarate known as positive modulators of the activity of malic enzymes from other sources were not observed either in cytoplasmic or mitochondrial enzymes from T. crassiceps. It was found that the two enzymes can be partly inhibited by ATP. Molecular weight of the malic enzyme from T. crassiceps cysticerci was determined by chromatography on Sephadex G-200 (Mw = 116,700) and a four-step purification of the enzyme was performed. The properties of malic enzymes from the cytoplasm and mitochondria of T. crassiceps are compared with those of the malic enzymes from other parasitic worms and higher organisms.     

Experimental infection of immunocompetent and immunodeficient mice with Encephalitozoon cuniculi

An experimental infection with the microsporidian Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 was studied using a model of immunocompetent BALB/c mice and immunodeficient SCID mice. The course of infection after intraperitoneal inoculation of E. cuniculi spores was evaluated using the presence of spores in peritoneal macrophages as a criterion. First significant decrease in the proportion of infected cells was recorded on day 9 post infection (p.i.) in BALB/c mice. From day 14 p.i. no spores were observed in macrophages from BALB/c mice, while the number of infected macrophages from SCID mice increased until the death of the mice. The natural killer (NK) cell activity of mouse splenocytes was compared with the production of interferon gamma (IFN-gamma) by these cells. While in BALB/c mice NK activity peaked on days 9 and 14 p.i., in SCID mice the marked increase of NK activity was recorded close before death of mice, on day 21 p.i. in correlation with the production of IFN-gamma. Production of specific antibodies was demonstrated from day 9 p.i. in sera from BALB/c mice. It is concluded that intraperitoneal infection of SCID mice with spores of E. cuniculi results in the marked increase in the number of peritoneal exudate cells and in the percentage of infected cells close before death of mice. Neither high activity of NK cells nor increased production of IFN-gamma are sufficient for the recovery of SCID mice from an E. cuniculi infection.     

Purification and properties of cytoplasmic malate dehydrogenase from Taenia crassiceps (Zeder, 1800) cysticerci

Malate dehydrogenase (L-malate: NAD oxidoreductase, EC 1.1.1.37) from the cytoplasm of Taenia crassiceps cysticerci was purified and the basic kinetic parameters of this enzyme were determined. The pH optimum range of enzyme reaction was found to be very wide: 8.8-11.0 for malate oxidation and 6.0-8.5 for oxaloacetate reduction. KM values for oxaloacetate, malate, NAD, and NADH were 7.8.10(-5) M, 1.4.10(-4) M, 1.2.10(-4) M, and 6.10(-5) M, respectively. Malate dehydrogenase activity was inhibited by malate excess. Molecular weight of malate dehydrogenase was 70,800. A comparison of the data obtained with those from other organisms including vertebrates showed that the cytoplasmic malate dehydrogenase from T. crassiceps is almost identical with the enzymes from other sources in its kinetic and regulatory properties, as well as in its molecular weight.     

Correlation of the results of IFAT-DASS and ELISA tests in experimental cysticercosis of mice

The sera of mice experimentally infected with Taenia crassiceps were tested for the occurrence of the antibodies by the enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence using defined antigen substrate spheres (IFAT-DASS). Results of both tests were compared. From day 11 p.i. until the end of the experiment (day 108 p.i.) antibodies were detected by both tests. The maximal intensity of the ELISA and IFAT-DASS reactions was observed between days 63 and 94 and days 14 and 46 p.i., respectively. ELISA is an easy-to-do and objectively appraisable method, IFAT-DASS is more suitable for testing antigens weakly adsorbing to polystyrene plates.     

Susceptibility of IFN-gamma or IL-12 knock-out and SCID mice to infection with two microsporidian species, Encephalitozoon cuniculi and E. intestinalis

Susceptibility of three strains of immunodeficient mice to two related microsporidian species Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 and Encephalitozoon intestinalis (Cali, Kotler et Orenstein, 1993) was compared. While both, severe combined immunodeficient (SCID) and interferon-gamma knock-out (IFN-gamma KO) mice, succumbed to either intraperitoneal (i.p.) or peroral (p.o.) (natural) infection with both parasites, only i.p. infection with E. cuniculi killed interleukin-12 knock-out (IL-12 KO) mice. IFN-gamma KO mice died earlier than SCID mice. Adoptive transfer of naive splenocytes from IFN-gamma KO mice did not protect the SCID mice from a lethal infection with either of the Encephalitozoon species. However, reconstituted mice survived significantly longer (P<0.05), thus indicating the role of IFN-gamma produced by host NK cells in the development of mechanisms of anti-microsporidial protective immunity. Non-lethal outcome of the infection always correlated with the increase in CD8+ T lymphocyte subpopulation. Both E. intestinalis-infected IFN-gamma KO and IL-12 KO mice produced comparable levels of specific antibodies, suggesting that antibodies did not protect IFN-gamma KO mice from lethal infection.     

Study of the properties of alkaline phosphatase in Taenia crassiceps (Zeder, 1800) cysticerci

The properties of alkaline phosphatase present in Taenia crassiceps cysticerci were studied. Approximately a half of the total activity was free and the remaining part was bound to membranes. Kinetic studies did not show any differences between the free and bound alkaline phosphatases. It was found that high substrate concentrations produced an inhibitory effect on the enzyme. This effect was much greater at lower pH. pH optimum changed with the concentration of the substrate.     

Study of cytochromes from mitochondria of Taenia crassiceps (Zeder, 1800) cysticerci

Cytochrome components of mitochondria from Taenia crassiceps cysticerci were studied by difference spectrophotometry (at 22 degrees C). The following concentrations of cytochromes (expressed in nmol X mg-1 protein) were found: 0.132 (cytochrome b), 0.083 (cytochrome c), and 0.0856 (cytochrome aa3). The participation of aerobic processes in the general production of energy is discussed and the results are compared with literary data obtained in cytochrome studies of other parasitic worms.     

Chalone-like inhibition of DNA synthesis in helminths

Chalone-like inhibitory activity was found in extracts from tissues of Taenia crassiceps cysticercus and tissues of adult Ascaris suum. The inhibitory effects were partially species nonspecific: The extracts from T. crassiceps larvae inhibit both T. crassiceps and Mesocestoides corti larvae DNA synthesis. Extracts from A. suum, however, inhibit only T. crassiceps. Besides them, the inhibitory factor from mouse brain inhibits both T. crassiceps and M. corti DNA synthesis. When the inhibitory factor from A. suum was applied 4 times during 24-hr culture (at 6-hr intervals), the inhibitory effect was decreased.     

Transhydrogenase activities in the mitochondria of Taenia crassiceps (Zeder, 1800) cysticerci

NADPH/NAD and NADH/NAD transhydrogenase activities have been demonstrated in the mitochondrial fraction of Taenia crassiceps cysticerci. These activities seem to result from the activities of two different enzyme systems. Both transhydrogenase activities exhibited a high heat resistence and they were completely abolished only by the temperatures higher than 100 degrees C. The activity of NADH/NAD transhydrogenase was rather high (116 nmol.min-1.mg-1 protein), but it was found to exhibit a low affinity to NADH (K'M = 1.43.10(-4) M). The physiological significance of NADH/NAD transhydrogenase is discussed.     

Immune response of the long-tailed field mouse (Apodemus sylvaticus) to tick-borne encephalitis virus infection.

The immune response following infection with a virulent strain of Central European encephalitis (CEE) virus in a natural host, long-tailed field mouse (Apodemus sylvaticus L.) and white laboratory-bread ICR mouse, was compared. Viraemia was demonstrated in ICR mice after intraperitoneal infection with a dose of 10(5) LD50/0.5 ml. The virus titres were high in the spleen and, particularly, in the brain. In A. sylvaticus the virus was detected in the blood and spleen, but not in the brain. CEE virus multiplied in peritoneal macrophages from ICR mice, but not from A. sylvaticus. The infection induced a strong interferon response in both hosts. The natural killer (NK) cell activity increase was twice as high in A. sylvaticus compared to ICR mice. The neutralization antibodies appeared sooner in A. sylvaticus and reached higher titres in the early phases of infection.     

Transfer of delayed hypersensitivity through repeatedly sensitized peritoneal exudate cells during experimental ancylostomiasis in mice

Current investigations using sensitized peritoneal exudate cells from mice infected repeatedly with Ancylostoma caninum larvae supply the evidence that these cells have the capability to transfer passive immunity to isogeneic recipients in contrast to normal cells from uninfected donors. High doses of sensitization to donors and a lapse of time between the expansion and proliferation of cells in the recipients provide a rather strong immunological readiness to expel/destroy the worm burden. The larvae bore through the gut reaching the peritoneal cavity but cannot enter the liver and/or lungs; they are thus misled (in the absence of normal guiding influences) to muscles where they undergo allergic death.     

Analysis of intestinal intraepithelial lymphocyte populations in experimental Trichinella spiralis infection of mice

The potential role of intestinal intraepithelial lymphocytes (i-IELs) in the generation of host protective immunity after helminth infection was investigated using the Trichinella spiralis (Owen, 1835)/mouse model. In this study we found a significant rise of TCRgamma(delta)+ i-IELs (P < 0.001) concurrent with the jejunal goblet cells (GC) hyperplasia in T. spiralis-infected C57BL mice on day 4 p.i. However, no direct relationship between the kinetics of the increase in TCRgamma(delta)+ i-IELs and T. spiralis expulsion was observed in infected mice. Taken together, these results implicate that gamma(delta) i-IELs probably perform a unique functions related to the regulation of the GC proliferation accompanying T. spiralis gut infection. As is known, these TCRgamma(delta)+ i-IELs may release mediators or growth factors that in turn influence GC differentiation. With the use of dexamethason (DEX), a potent anti-inflammatory agent which also induces apoptotic cell death in i-IELs, we have confirmed that the expulsion of T. spiralis from the mouse gut is accompanied by an inflammatory response. Indeed, the GC are clearly involved in these phenomena, apparently under the regulation by TCRgamma(delta)+ i-IEL-mediated responses, since DEX abrogated GC proliferation in T. spiralis-infected C57BL mice and subsequently augmented adult worm burden. Our data also show that the rejection of adult worms starts concurrently with a significant increase in TCRalpha(beta)+ and CD8+ i-IELs (P < 0.05 and P < or = 0.01, respectively), namely by day 7 p.i. At the same time, CD4+ cells significantly decreased (P < 0.05) in the intestinal epithelium of T. spiralis-infected, vs uninfected mice. These results may indicate that the TCRalpha(beta)+ and CD8+ i-IELs act as effectors of anti-T spiralis defence reactions. The implications of these findings for the potential role of intestinal intraepithelial CD8+ and TCRalpha(beta)+ cells in the pathogenesis of the intestinal lesions during T. spiralis gut infection are discussed.     

The dynamics of eosinophilia in concurrent infections with Trichinella spiralis Owen, 1835 and Toxascaris leonina Linstow, 1909

The concurrent infection with larvae of Trichinella spiralis and eggs of Toxascaris leonina was studied under various conditions using 75 male white mice. The changes in content of eosinophilic leucocytes in the blood, as well as the total number and distribution of larvae of both parasites in different body tissues were demonstrated. The primary infection with Toxascaris leonina caused an increase in the number of eosinophilic leucocytes from day 4 p.i., whereas the infection with Trichinella spiralis larvae induced an increase only from day 7 p.i. An antagonism was observed between the two parasite species: the primary infection with T. leonina led to a decrease in the total number of muscle larvae of T. spiralis, and, vice versa, the primary infection with T. spiralis suppressed the development of T. leonina.     

Pathology of the migration phase of Taenia hydatigena (Pallas, 1766) larvae

The pathological picture of the migration phase of C. tenuicollis in pigs is characterized by a haemorrhagia within the liver parenchyma and under the liver surface. The haemorrhagia, which represents a migrational canal, is induced by the destruction of liver sinuses by migrating larvae. Approximately on day 10 p.i. a serofibrinous peritonitis occurs and free cysticerci appear in the exudate. On days 14-16 p.i. the exudative peritonitis may increase. The cysticerci are localized under the serosas or on them. On about day 10 p.i. even the pulmonary form of the disease may occur. On day 13 p.i. the cysticerci are present in the lumen of lung arteries or they migrate out of them. The changes in the lungs and on the pleura, as well as their dynamic changes, are identical with the changes in the liver and on the peritoneum. The period on days 21-24 p.i. is characterized by extensive synechiae of serosas and the cysticerci are firmly attached to the serosas. On day 35 p.i. the connective tissue adhesions persist and many of the cysticerci exhibit dystrophic changes or are dead and often already calcified. The wall of the pseudocyst, in which the cysticercus is situated, consists of the fibrocytes and serosa, and its cavity is not lined with endothelium, as it is the case in C. bovis and C. cellulosae.     

Attenuation of Schistosoma mansoni cercarial infectivity to albino mice by methanol extract of some plant species

This study elucidates the activity of certain plants’ methanol extract: Anagallis arvensis, Solanum nigrum (green fruits), Chenopodium ambrosioides, Calendula officinalis and Sesbania sesban, on the infectivity of S. mansoni cercariae to albino mice. Then, some parasitological parameters, e.g. the worm load/mouse, number of ova/g tissue in liver and intestine and the developmental stages of ova in the small intestinal wall (Oogram) of infected mice were determined. In addition, certain biochemical parameters of serum from infected mice (total protein, albumin, the activities of AlT, AsT, AcP and AkP enzymes) were, also, recorded.The results showed that exposure of S. mansoni cercariae for 30 min to the tested plants’ methanol extract before mice infection has a higher suppressive effect on their infectivity to albino mice then those exposed to this extract during mice infection. The number of worms recovered/infected mouse and the number of ova/g tissue from liver and intestine of mice groups infected with cercariae exposed to the tested plants’ methanol extract either pre- or during mice infection were less than those of infected control groups (e.g. the reduction rates of worm load/mouse and number of ova/g tissue in the intestine were 46.1% and 76.8%, respectively, for mice infected with cercariae exposed to 5 ppm of A. arvensis during mice infection).The results, also, indicated that exposing S. mansoni cercariae to methanol extract of the experimental plants either pre- or during mice infection reduced the activities of the enzymes AlT, AsT, AcP and AkP that were elevated in mice infected with untreated cercariae, meanwhile, the concentrations of total protein and albumin were increased in the serum of mice infected with these treated cercariae in comparison with those of mice group infected with untreated cercariae.     

Leptin and leptin receptors during malaria infection in mice

Leptin, which is involved in a range of physiological processes, could be an important factor in the pathogenesis of malaria. We found that levels of leptin in serum and urine in Plasmodium berghei-infected mice increased progressively after infection, reaching a maximum value on day 6 post-infection. Serum values were approximately five-fold higher in infected mice than in non-infected controls. A similar relation was found for values of leptin in urine. Soluble leptin receptor levels also increased significantly in serum, more or less in line with the leptin increase. Our work represents the first report of visibly augmented leptin and soluble leptin receptor secretion in malarial infection.     

Effect of vitamins on Trichinella spiralis Owen, 1835 infection in mice

The effects of vitamins A, B complex, E, and ADE on the body weight, eosinophilia, intensity of infection and distribution of T. spiralis larvae were studied in mice. The greatest loss of weight followed after the application of vitamins B complex and E. An increased eosinophilia appeared in the majority of infected mice since day 7 p.i., reaching the maximum on day 21 p.i. In mice receiving vitamins B complex, A, and ADE, the increased eosinophilia was observed still on day 60 p.i. The highest levels of eosinophilia occurred after the application of vitamins B complex and E, which was directly proportional to the intensity of infection. The lowest intensity of infection was recorded in mice receiving vitamin A. Though there were great differences between individual mice, the greatest number of larvae were localized in the diaphragm and left masseter.     

Dynamics of antibody production in mice infected with Toxascaris leonina Linstow, 1909

Using counterimmunoelectrophoresis and ELISA tests the dynamics of antibody production in serum of mice experimentally infected with Toxascaris leonina was studied. The production of antibodies using both tests has already been detectable in serum of mice from 7 days post infection (DPI) and their level persisted till the end of the experiment, i.e. till 77 DPI. The most positive were reactions of sera with Antigens 1 and 3.