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Showing papers in "Journal of Parasitology in 1989"



Journal ArticleDOI
TL;DR: Blood stream forms (BSF) of Trypanosoma brucei Brucei GUT were propagated in vitro in the absence of feeder layer cells at 37 C, using a modified Iscove's medium (HMI-18), and long slender BSFs increased in number from day 4 onward.
Abstract: Blood stream forms (BSF) of Trypanosoma brucei brucei GUT at 3.1 were propagated in vitro in the absence of feeder layer cells at 37 C, using a modified Iscove's medium (HMI-18). The medium was supplemented with 0.05 mM bathocuproine sulfonate, 1.5 mM L-cysteine, 1 mM hypoxanthine, 0.2 mM 2-mercaptoethanol, 1 mM sodium pyruvate. 0.16 mM thymidine, and 20% (v/v) Serum Plus (SP) (Hazleton Biologics, Lenexa, Kansas). The latter contained a low level of serum proteins (13 micrograms/ml). Each primary culture was initiated by placing 3.5-4 x 10(6) BSFs isolated from infected mice in a flask containing 5 ml of the medium (HMI-9) supplemented with 10% fetal bovine serum (FBS) and 10% SP. The cultures were maintained by replacing the medium every 24 hr for 5-7 days. During this period, many BSFs died. However, from day 4 onward, long slender BSFs increased in number. On days 5-7, trypanosome suspensions were pooled and cell debris was removed by means of diethylaminoethyl cellulose (DE52) column chromatography. Blood stream forms then were collected by centrifugation, resuspended in fresh medium at 7-9 x 10(5)/ml, and transferred to new flasks. Subcultures were maintained by readjusting the BSF density to 7-9 x 10(5)/ml every 24 hr. Concentrations of FBS were reduced gradually at 5-7-day intervals by alternating the amounts of FBS and SP in HMI-9 with 5% FBS and 15% SP, with 2% FBS and 18% SP, and finally with 20% SP (HMI-18). By this method, 2-3 x 10(6) VSFs/ml were obtained consistently every 24 hr. for more than 80 days.(ABSTRACT TRUNCATED AT 250 WORDS)

950 citations


Journal ArticleDOI
TL;DR: A new apicomplexan species, Perkinsus atlanticus, is described from gill filaments of the clam Ruditapes decussatus (Bivalvia) from Portugal, where it causes great mortality.
Abstract: A new apicomplexan species, Perkinsus atlanticus, is described from gill filaments of the clam Ruditapes decussatus (Bivalvia) from Portugal, where it causes great mortality. The zoospores differ from those of other species of Perkinsus in size and shape, dimensions, insertion of the 2 flagella, and in the identity of the host. On the other hand, the life cycle stages showed some ultrastructural differences compared with Perkinsus marinus, the only species previously studied in detail. When the clams were parasitized heavily, ultrastructurally similar life cycle stages were found in foot and mantle tissues.

203 citations


Journal ArticleDOI
TL;DR: Findings indicate that passive lacteal immunity conferred partial protection against cryptosporidiosis in neonatal calves, and whether such protection was provided by the immunoglobulins that were highly elevated in the colostrum and constituted a large part of the circulating antibody in the calves, is undetermined.
Abstract: Twelve neonatal calves were experimentally infected with oocysts of Cryptosporidium parvum. Six calves in group A fed hyperimmune colostrum at birth had significantly less diarrhea and shed oocysts for less time than did 6 calves in group B fed colostrum from cows that were not hyperimmune. Calves in group A had diarrhea for 0-4 days (means = 2.3 days), whereas calves in group B had diarrhea for 4-6 days (means = 5.0 days). Calves in group A shed oocysts for 4-9 days (means = 6.2 days), whereas calves in group B shed oocysts for 7-11 days (means = 8.5 days). These findings indicate that passive lacteal immunity conferred partial protection against cryptosporidiosis. Whether such protection was provided by the immunoglobulins that were highly elevated in the colostrum (greater than 1:200,000 for IgG1, IgM, and IgA) and constituted a large part of the circulating antibody in the calves, or by other biologically active factors, such as cytokines, is undetermined.

121 citations


Journal ArticleDOI
TL;DR: Correlation between parasite phylogeny and taxonomic affinities of their definitive hosts suggests that the definitive hosts of heteroxenous sporozoa are their ancestral hosts.
Abstract: A phylogenetic analysis of representative genera in the class Sporozoea was undertaken using biological and morphological features to infer evolutionary relationships among the widely recognized groups in the class. Gregarines were used as a functional outgroup to the remaining sporozoa (adeleids, eimeriorins, haemosporinids, and piroplasms). The piroplasms were shown to be closely related to the adeleid parasites. Species of Babesia and Theileria were shown not to form a sister group to the haemosporinids as has been frequently suggested. The data indicate that the biologically diverse family Haemogregarinidae should be divided into at least 3 families (Haemogregarinidae Neveu-Lemaire, 1901, containing the genera Haemogregarina and Cyrilia; Karyolysidae Wenyon, 1926, containing the genus Karyolysus; Hepatozoidae Wenyon, 1926, containing the genus Hepatozoon) because the 4 genera currently within the family do not form a monophyletic group. Correlation between parasite phylogeny and taxonomic affinities of their definitive hosts suggests that the definitive hosts of heteroxenous sporozoa are their ancestral hosts. Heteroxenous sporozoan life cycles apparently have evolved independently to adapt to changes in the feeding behaviors of their definitive hosts.

116 citations


Journal ArticleDOI
TL;DR: Mice given 4 mg MPA and tachyzoites and host cells that had been frozen for 1 wk did not develop clinical signs of infection, indicating that freezing kills tachyzosites and that viruses or other agents were not involved in the genesis of disease seen in mice given MPA
Abstract: Groups of mice were given 0 mg, 4 mg, or 2 mg of methylprednisolone acetate (MPA) 7 days prior to, the day of, and 7 days after subcutaneous inoculation with 0 or 2 x 10(5) tachyzoites of Neospora caninum. Clinical signs of disease were seen only in mice given both MPA and N. caninum tachyzoites. Mice given 4 mg MPA and N. caninum tachyzoites developed severe disseminated neosporosis and most died or were killed when comatose 11-13 days postinoculation (PI). Acute pneumonia, polymyositis, encephalitis, hepatitis, and pancreatitis were the main lesions in these mice. Mice given 2 mg MPA and N. caninum developed mild pneumonia and many mice began showing neurological signs 14 days PI. Neurological signs consisted mainly of pronounced head-tilting and associated impairment of movement. Grossly visible 1-2-mm single or multiple, white areas of discoloration were seen in the brains of many of these mice. Encephalitis, ganglioradiculoneuritis, pneumonia, and polymyositis were the main changes seen in these mice. Tissue cysts of N. caninum were only seen in mice given 2 mg MPA and were first seen 21 days PI. Tissue cysts were 16-34 by 13-29 microns and had a 1.5-3.0-microns-thick cyst wall. Tissue cysts were seen only in the brain. Mice given 4 mg MPA and tachyzoites and host cells that had been frozen for 1 wk did not develop clinical signs of infection, indicating that freezing kills tachyzoites and that viruses or other agents were not involved in the genesis of disease seen in mice given MPA and viable tachyzoites.(ABSTRACT TRUNCATED AT 250 WORDS)

103 citations


Journal ArticleDOI
TL;DR: The development of Neospora caninum isolated from naturally infected dogs was examined in mammalian cell cultures and it appears that N.Caninum can be continuously grown in cell cultures.
Abstract: The development of Neospora caninum isolated from naturally infected dogs was examined in mammalian cell cultures. Tachyzoites developed by endodyogeny when inoculated onto bovine monocyte or bovine cardiopulmonary artery endothelial cell cultures. Tachyzoites were 5.0 by 2.0 microns and had a posteriorly located nucleus. Cytopathogenic effects of parasite development consisted of the formation of holes in the cell monolayer associated with the rupture of infected host cells. Serial passage of tachyzoites was achieved by subinoculation of tachyzoites onto non-infected bovine monocyte cell cultures. It appears that N. caninum can be continuously grown in cell cultures.

94 citations


Journal ArticleDOI
TL;DR: Parish et al. as discussed by the authors found Neospora caninum-like organisms in histologic sections of spinal cord of 4 paralyzed calves and reported that the tissue cysts were up to 62 microns wide and the cyst wall was up to 2.5 microns thick.
Abstract: Neospora caninum-like organisms were found in histologic sections of spinal cord of 4 paralyzed calves as reported by Parish et al. (1987). Tachyzoites divided by endodyogeny. Tissue cysts were up to 62 microns wide and the cyst wall was up to 2.5 microns thick. The organism in calves was structurally distinct from Toxoplasma gondii and Sarcocystis species and reacted positively with anti-N. caninum serum in an immunoperoxidase test.

81 citations


Journal ArticleDOI
TL;DR: Activity of colostral whey, produced by a cow immunized with oocysts of Cryptosporidium parvum and found to provide prophylaxis against cryptosporidiosis in calves, was tested in 2 experiments and it was determined that protection was mediated by specific anti-sporozoite activity.
Abstract: Activity of colostral whey, produced by a cow immunized with oocysts of Cryptosporidium parvum and found to provide prophylaxis against cryptosporidiosis in calves, was tested in 2 experiments. In one experiment BALB/c mice were given the immune whey (HW), whey from a nonimmunized cow (CW), or a balanced salt solution (HBSS) before, during, and after oral inoculation with oocysts of C. parvum. Significantly fewer (P less than 0.05) C. parvum were found in mice that received HW (undiluted, 1:20 or 1:50) than in those treated with similarly diluted CW or with HBSS. In the second experiment it was determined that protection was mediated by specific anti-sporozoite activity when significantly fewer (P less than 0.05) C. parvum were found in mice that received sporozoites treated with HW diluted 1:20 or 1:50 compared with mice that received sporozoites treated with similarly diluted CW or with HBSS.

79 citations


Journal ArticleDOI
TL;DR: Although birds may help establish new foci of ticks, catbirds, at least, do not appear to contribute as reservoirs of infection.
Abstract: We compared the relative infectivity to vector ticks of gray catbirds (Dumetella carolinensis) and white-footed mice (Peromyscus leucopus) for the Lyme disease spirochete (Borrelia burgdorferi). Of 28 catbirds captured in a site enzootic for this agent, 18 were infested by immature Ixodes dammini, the tick vector. By comparison, each of 32 mice sampled concurrently from the same site was infested, and by about 10 times as many ticks as were found infesting the 3 most commonly netted bird species. Although 76% of noninfected larval ticks placed on these mice in a xenodiagnosis became infected, none of the ticks similarly placed on 12 catbirds did so. Spirochetes were detected in ticks derived from 2 Carolina wrens (Thryothorus ludovicianus) and a common yellowthroat (Geothlypis trichas), but these species' potential contribution to infecting ticks does not compare with that of mice. Thus, although birds may help establish new foci of ticks, catbirds, at least, do not appear to contribute as reservoirs of infection.

68 citations


Journal ArticleDOI
TL;DR: Phylogenetic analysis of selected subfamily and family taxa within the Dactylogyroidea indicates that the Ancyrocephalidae Bychowsky, 1937, is unnatural and suggests that revision of the Ancentylogyridae is necessary.
Abstract: Phylogenetic analysis of selected subfamily and family taxa within the Dactylogyroidea indicates that the Ancyrocephalidae Bychowsky, 1937, is unnatural. The family contains both poly- and paraphyletic features. The analysis supports the previous elevation of the Pseudomurraytrematinae to family status and suggests that revision of the Ancyrocephalidae is necessary. Two options for revision are provided; that of returning the taxon to subfamily status within the Dactylogyridae is preferred, requiring a change in status of the Heterotesiidae to a subfamily within the Dactylogyridae.

Journal ArticleDOI
TL;DR: The phagocytic activity of hemocytes from 6-8-mm M-line Biomphalaria glabrata snails was studied in an in vitro assay using glutaraldehyde-fixed sheep erythrocytes (SRBC) as target cells and revealed a low PAI, compared to snails exposed to infection but subsequently lacking IS, which had a significantly higher PAI.
Abstract: The phagocytic activity of hemocytes from 6-8-mm M-line Biomphalaria glabrata snails was studied in an in vitro assay using glutaraldehyde-fixed sheep erythrocytes (SRBC) as target cells. For individual snails, the percentage of hemocytes ingesting SRBC during a 1-hr interval, termed the phagocytic activity index (PAI), was determined. Hemocytes from snails infected for 1 day with Echinostoma paraensei had a slightly elevated PAI, but at both 8 and 30 days postexposure (DPE), hemocytes from infected snails had a significantly lower PAI than controls. Hemocytes taken from snails at 8 DPE also had a low PAI using rabbit erythrocytes and yeast as target cells. The low PAI at 8 DPE is attributed to the presence of large numbers of poorly spreading hemocytes with low phagocytic activity. Hemocytes from snails with 30-day infections were well spread but nonetheless had a low PAI. The presence of plasma from 8-day infected snails did not alter the PAI of hemocytes from control snails, nor was the PAI of hemocytes from infected snails changed by plasma from control snails. SRBC preincubated for 60 min in plasma from various groups of M-line snails did not elicit an increase in PAI when presented to hemocytes from control snails; in some cases, as with plasma from 6-8-mm control snails, such preincubation significantly reduced the PAI below levels obtained using SRBC preincubated in culture medium. As compared to hemocytes from snails with normally developing, 8-day-old intraventricular sporocysts (IS), hemocytes from snails exposed to infection but subsequently lacking IS had a significantly higher PAI.(ABSTRACT TRUNCATED AT 250 WORDS)

Journal ArticleDOI
TL;DR: Experiments involving the inoculation of [3H]thymidine along with mff or saline alone and studies involving the administration of colchicine suggest that increased hemocyte populations in immune-activated A. aegypti are a result of mitotic division of circulating blood cells.
Abstract: Ultrastructural and lectin-binding studies have established that the melanotic encapsulation reaction of Aedes aegypti Liverpool strain against inoculated Dirofilaria immitis microfilariae (mff) is a hemocyte-mediated reaction. Total hemocyte counts from mff-inoculated (= immune-activated), saline-inoculated, and uninoculated female A. aegypti were determined using a hemocoel perfusion technique. Total hemocyte populations in uninoculated mosquitoes were significantly larger in younger mosquitoes, but no significant change was noted as mosquitoes aged beyond 14 days. Hemocyte populations in immune-activated mosquitoes increased from 1 to 3 days postinoculation (PI) and decreased on days 4 and 5 PI. Hemocyte populations at 1 to 4 days PI were significantly elevated in mff-inoculated A. aegypti as compared with saline-inoculated controls. Saline-inoculated mosquitoes displayed little change in total hemocyte numbers from 1 to 5 days PI, and their hemocyte populations were similar to those seen in uninoculated insects of the same age. Experiments involving the inoculation of [3H]thymidine along with mff or saline alone and studies involving the administration of colchicine suggest that increased hemocyte populations in immune-activated A. aegypti are a result of mitotic division of circulating blood cells.

Journal ArticleDOI
TL;DR: In conclusion, antigen presentation by Toxoplasma-infected cells for activation of both cytotoxic and proliferative T cells has been demonstrated.
Abstract: Cytotoxic cells specific for Toxoplasma gondii-infected cells were detected in the peripheral blood leukocytes from a patient with acute toxoplasmosis. The cytotoxicity was mediated by CD5+, CD4-, CD8+ cells. The cytotoxic T cells lysed Toxoplasma-infected target cells with HLA class I restriction. Two types of T cell clones were established from peripheral blood leukocytes of a patient with chronic toxoplasmosis; one was a CD5+, CD4-, CD8+ cytotoxic cell specific for Toxoplasma-infected cells, and the other was a CD5+, CD4+, CD8- proliferative cell that responded to Toxoplasma antigen. Toxoplasma-infected cell-specific cytotoxic cloned T cells recognize the infected target cells in the context of the HLA class I molecules, and the CD8 molecule was involved in the cytotoxicity. Toxoplasma antigen-specific proliferative cloned T cells were stimulated by Toxoplasma antigen-pulsed or Toxoplasma-infected cells in conjunction with HLA-DR molecule on the target cells. Thus, antigen presentation by Toxoplasma-infected cells for activation of both cytotoxic and proliferative T cells has been demonstrated.

Journal ArticleDOI
TL;DR: Les caracteristiques du parasitisme par le trematode dans la cohorte d'escargots sont etudiees and une methode de marquage-lâcher-recapture est utilisee pour suivre le cours des infections.
Abstract: Etude de la dynamique des interactions entre H. anceps et H. occidualis pendant les mois d'hiver en utilisant des escargots marques individuellement. Les caracteristiques du parasitisme par le trematode dans la cohorte d'escargots sont etudiees et une methode de marquage-lâcher-recapture est utilisee pour suivre le cours des infections

Journal ArticleDOI
TL;DR: Patterns of similarity and overlap in species presence and patterns of linear distribution of intestinal helminths in 22 avocets from 4 populations are reported.
Abstract: This paper reports patterns of similarity and overlap in species presence and patterns of linear distribution of intestinal helminths in 22 avocets from 4 populations. Avocets collected from ephemeral bodies of water in Alberta and Manitoba had communities composed largely of species that are avocet specialists plus some that are host generalists. The composition of helminth communities in these hosts was similar to that reported in earlier surveys of avocet helminths. There was little evidence for competition between helminth species in these communities. In contrast, avocets collected from permanent bodies of water in Alberta had communities composed largely of species that are specialists in various duck species, particularly lesser scaup. These helminths were superimposed on the normal community, fitting into linear gaps along the intestine but also overlapping the distributions of avocet specialists. These lesser scaup specialists exhibit interactive patterns amongst themselves and, to some extent, with avocet specialists. Helminth communities in avocets from ephemeral bodies of water have vacant niches and are largely isolationist in nature. Those in avocets from permanent bodies of water are saturated and are more interactive in nature.

Journal ArticleDOI
TL;DR: It is concluded that higher levels of phenoloxidase in the refractory strain following a blood meal may contribute to the ability to encapsulate ookinetes.
Abstract: A melanogenic enzyme, phenoloxidase, was localized ultrastructurally in the midgut epithelia of 2 strains of Anopheles gambiae, a refractory strain that melanotically encapsulates Plasmodium cynomolgi ookinetes on the midgut, and a susceptible strain that does not. Midguts were incubated with either dopa or dopamine, and the resultant electron-dense product of phenoloxidase activity was localized on the basal lamina (BL) and cellular basal membrane labyrinth (BML) in uninfected mosquitoes of both strains. In infected refractory mosquitoes, the reaction products still were observed on the BL and BML but were especially dense in the BML of midgut cells near encapsulated ookinetes and in the capsule itself. In infected susceptible mosquitoes, phenoloxidase localization was reduced or absent in the BL and BML and was not observed near parasites. Phenylthiourea (PTU) inhibited the phenoloxidase reaction, indicating that the reaction product deposited in the absence of PTU resulted from enzyme activity and not autooxidation of the substrates. It is concluded that higher levels of phenoloxidase in the refractory strain following a blood meal may contribute to the ability to encapsulate ookinetes.

Journal ArticleDOI
TL;DR: Ecological diversification is more conservative evolutionarily than diversification in developmental patterns, indicated by the appearance of unique larval stages, asexual proliferation of larvae, polyembryony, and heterochronic changes.
Abstract: The unified theory of evolution is an expansion of Darwinian theory that asserts that evolution is driven by entropic accumulation of genetic information that is constrained and organized primarily by the genealogical effects of phylogenetic history and developmental integration, and secondarily by ecological effects, or natural selection in its classical mode. Phylogenetic systematic analysis of the 8 major groups of parasitic rhabdocoelous platyhelminths permits empirical macroevolutionary evaluation of these postulates. Of the 131 characters considered, 127 are phylogenetically constrained, and 4 show evidence of 1 case of convergence each. Data from different developmental stages are phylogenetically congruent, despite differences in ecology among those stages. Ecological diversification, indicated by phylogenetic association of definitive hosts and parasites, and by changes in ecological components of life cycle patterns, is more conservative evolutionarily than diversification in developmental patterns, indicated by the appearance of unique larval stages, asexual proliferation of larvae, polyembryony, and heterochronic changes. These observations support the macroevolutionary postulates of the unified theory.

Journal ArticleDOI
TL;DR: Eight samples of desiccated human feces collected from Big Bone Cave were analyzed to determine the presence of ecto- and endoparasitic infection among the prehistoric population using the cave and cysts identified as Giardia were identified, the first report ofGiardia from paleofeces in the New World.
Abstract: Eight samples of desiccated human feces collected from Big Bone Cave (40VB103), Van Buren County, Tennessee, were analyzed to determine the presence of ecto- and endoparasitic infection among the prehistoric population using the cave. Radiocarbon-dated torch material from the cave indicated that it was a locus of human activity 2,177 +/- 145 yr ago. Parasitic species identified were: Ascaris lumbricoides, Enterobius vermicularis, fleas of the tribe Phalacropsyllini, and protozoan cysts. The cysts were identified as Giardia using an indirect immunofluorescent antibody test. The only report of Giardia in a prehistoric context is the identification of cysts in 2 1,800-yr-old paleofecal specimens from a cave in Israel. This is the first report of Giardia from paleofeces in the New World.

Journal ArticleDOI
TL;DR: It is shown that S. mansoni primary sporocysts, cultured in vitro, synthesize and secrete a wide variety of glycoproteins and that the type and quantity of glyCoproteins released are dependent on culture conditions.
Abstract: Excretory-secretory (E-S) products released by larval schistosomes have been implicated in the interference of host snail defense systems. Because of the potentially important role that E-S products play in the parasite-host relationship, total and newly synthesized E-S proteins from in vitro-cultured Schistosoma mansoni primary sporocysts were characterized using incorporation of [35S]methionine followed by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography. Total E-S protein decreased more than 5-fold from day 1 to day 3 of culture and remained constant until day 8 when protein concentrations began to increase. Release of newly synthesized protein, however, increased from day 1 through day 8. Both silver staining and fluorography of SDS-PAGE-separated E-S products revealed a wide variety of polypeptides ranging in Mr from 13 to greater than 200 kDa. The dynamics of the release of individual polypeptides, both total and newly synthesized, varied over time. Although certain polypeptides decreased in concentration, others remained constant or increased with time in culture. Culture conditions were found to be important for sporocyst viability and growth, and for release of newly synthesized proteins. Sporocysts cultured in medium containing fetal bovine serum (complete) grew significantly larger and had a significantly greater viability than did sporocysts cultured in medium lacking serum (incomplete). Also, sporocysts cultured in complete medium synthesized and released significantly more protein than did sporocysts cultured in incomplete medium. These sporocysts continued to produce a 54-kDa polypeptide, whereas sporocysts in incomplete medium stopped producing this protein by day 3 of culture. The present study has shown that S. mansoni primary sporocysts, cultured in vitro, synthesize and secrete a wide variety of glycoproteins and that the type and quantity of glycoproteins released are dependent on culture conditions.

Journal ArticleDOI
TL;DR: Genetic susceptibility of mosquitoes to infection by filarial worms and potential mechanisms of immune evasion/suppression are discussed regarding B. malayi and B. pahangi.
Abstract: The inherent ability of Brugia malayi and Brugia pahangi (Nematoda) to establish successful relationships with the mosquitoes Armigeres subalbatus and Aedes aegypti Liverpool strain was evaluated. Brugia pahangi microfilariae (mff) avoided the immune response and developed normally in A. subalbatus exposed to the parasite by an infective bloodmeal, whereas nearly 85% of B. malayi were destroyed by the immune response. Because A. aegypti supports the development of both filarial worm species but destroys intrathoracically inoc- ulated B. pahangi isolated from jird blood, blood-isolated B. malayi were inoculated into A. aegypti, and the immune response was compared with that observed against B. pahangi. The response against B. malayi was significantly more rapid and effective than the response against B. pahangi. Similar results were obtained when blood-isolated B. pahangi or B. malayi were inoculated into A. subalbatus. Microfilariae of both species were able to avoid immune destruction in A. aegypti if they were allowed to penetrate the Liverpool midgut in vitro prior to inoculation. Most B. pahangi that had first penetrated an Armigeres midgut prior to inoculation into A. subalbatus were able to avoid the immune response, but by day 3 postinoculation, less than 40% of the B. malayi, treated in the same manner, were able to escape the immune response. Genetic susceptibility of mos- quitoes to infection by filarial worms and potential mechanisms of immune evasion/suppression are discussed regarding B. malayi and B. pahangi.

Journal ArticleDOI
TL;DR: Results demonstrated that the cyst wall of Giardia spp.
Abstract: High-resolution morphological studies of the cyst wall of Giardia spp. were performed using low-voltage scanning electron microscopy (LVSEM) and transmission electron microscopy (TEM). The cyst wall was composed of membranous and filamentous layers. The membranous layer consisted of an inner and an outer cyst membrane separated by a thin layer of cytoplasm. The filamentous layer contained individual filaments that ranged from 7 to 20 nm in diameter when measured by LVSEM, formed a dense meshwork with branches or interconnections, and were occasionally arranged on the surface in whorled patterns. Cysts of Giardia muris from mice, Giardia duodenalis from dogs, pigs, voles, beavers, muskrats, and humans, and Giardia psittaci from a bird (parakeet), possessed an essentially identical wall composed of filaments. Inducement of excystation in viable Giardia cysts produced a dramatic increase in the interfilament spacing over an entire cyst, but none was observed in heat-killed or chemically fixed control cysts. These results demonstrated that the cyst wall of Giardia spp. was composed of a complex arrangement of filaments, presumably formed during the process of encystment.

Journal ArticleDOI
TL;DR: The course of parasitemia of cloned Trypanoplasma borreli in laboratory-infected common carp was investigated and the prepatent period lasted longer and the generation time was increased, but the level of Parasitemia was not affected.
Abstract: The course of parasitemia of cloned Trypanoplasma borreli in laboratory-infected common carp was investigated. In 25-42-g carp kept at 20 C, the prepatent period was 8 days; after a phase of exponential growth, the parasitemia peaked at day 39 postinjection (PI) at a level of about 10(3) T. borreli/microliters blood. This maximum was followed by a chronic phase of about 6 wk with large numbers of T. borreli. At 20 wk PI, T. borreli was absent in infected carp. In 2.2-g carp kept at 20 C, the prepatent period was 4 days only, and the parasitemia peaked at day 23 PI. At 30 C, T. borreli was present in the blood only for 12 wk, and the number of T. borreli did not exceed 162 trypanoplasms/microliters blood. Carp kept at 8 and 15 C showed retarded development of parasitemia. The prepatent period lasted longer and the generation time was increased, but the level of parasitemia was not affected. Carp, inoculated at 8 C and then warmed to 20 C on days 27 and 55 PI, developed a parasitemia of 10(4) flagellates/microliters blood and showed high mortalities. During the prepatent period, T. borreli was found in the muscle tissue of the inoculation area but in no other tissue. In the kidney, T. borreli was found 27 hr PI, whereas in the circulating blood it was manifest at day 3 PI. At the same time it was manifest in the liver and spleen.

Journal ArticleDOI
TL;DR: Results indicate that T. gondii infection in sheep in the United States is widespread and increased with age of the ewe, and on certain farms, up to 95% of ewes were seropositive.
Abstract: Of 1,564 serum samples from adult ewes from 33 farms in Iowa, Minnesota, South Dakota, Kansas, and Nebraska where toxoplasmosis-induced ovine abortions had been diagnosed, 65.5% were found positive for Toxoplasma gondii antibodies using the modified agglutination test. Toxoplasma gondii antibody titers of ewes were: less than 64 (34.5%), 64 (14.9%), 256 (22.0%), 1,024 (14.5%), and greater than 4,096 (13.8%). Thus, 28.3% of sheep had high titers (greater than 1,024) indicating recently acquired T. gondii infection. On certain farms, up to 95% of ewes were seropositive. Prevalence of T. gondii antibodies increased with age of the ewe. Of 665 ewes, 53.6% of 1-yr-old ewes were seropositive (titers greater than 64) versus 75% of 5-yr-old ewes. Results indicate that T. gondii infection in sheep in the United States is widespread.

Journal ArticleDOI
TL;DR: Results indicate that N. caninum can be transplacentally transmitted in cats during acute and chronic stages of infection.
Abstract: Transplacental transmission of Neospora caninum was studied in 2 pregnant cats (queens). Queen 1 was inoculated subcutaneously with 2 x 10(6) cell culture-derived N. caninum tachyzoites on day 47 of gestation. She gave birth to a full-term kitten on the 17th day after inoculation. The kitten died the second day after birth due to generalized N. caninum infection. The mother cat was killed on the third day after parturition and was found to have a macerated kitten in the uterus. Severe placentitis, metritis, hepatitis, and nephritis due to N. caninum were seen in tissues from the queen. Queen 2 was fed N. caninum tissue cysts and mated 111 days later. She gave birth to 3 healthy full-term kittens. The kittens were necropsied at 2, 22, and 30 days of age. Neospora caninum was recovered from the organs and was seen in histologic sections in 1 of the 3 kittens. Results indicate that N. caninum can be transplacentally transmitted in cats during acute and chronic stages of infection. Neospora caninum-specific IgG antibodies were demonstrated in the sera of inoculated cats and nursing kittens.

Journal ArticleDOI
TL;DR: In an identical study of Rhipicephalus zambeziensis, a closely related rhipicephalid, the immune response was not suppressed, indicating that immune suppression is not common to the genus Rhip icephalus.
Abstract: The brown ear tick Rhipicephalus appendiculatus suppressed in vivo and in vitro immune responses in the rabbit. Humoral responses were suppressed during infestation; however, suppression was transient and was unrelated to previous exposure of hosts to similar tick infestations. Immune suppression was caused by putative lymphocytotoxic factor(s) in tick salivary secretions as evidenced by in vitro lymphocytotoxicity assays. In an identical study of Rhipicephalus zambeziensis, a closely related rhipicephalid, the immune response was not suppressed, indicating that immune suppression is not common to the genus Rhipicephalus.

Journal ArticleDOI
TL;DR: To investigate the oocyst-induced cycle with a 21+ day prepatent period, 32 cats were fed sporulated oocysts of Toxoplasma gondii and necropsied between 4 hr and 41 days thereafter and bradyzoites predominated in extraintestinal organs during the first 14 days after infection.
Abstract: To investigate the oocyst-induced cycle with a 21+ day prepatent period, 32 cats were fed 5 x 10(5) to 2 x 10(7) sporulated oocysts of Toxoplasma gondii and necropsied between 4 hr and 41 days thereafter. The presence of the earliest stages in 7 cats was tested in mice. The tissues of 25 cats were studied histologically; 17 were bioassayed by feeding them to cats to determine, by the length of the prepatent period, whether bradyzoites were present. Based on previous studies, a short (3-10 days) prepatent period indicated that bradyzoites were present in an oral inoculum and a long (greater than 21 days) prepatent period indicated the presence of tachyzoites only. Tissues from 14 cats were also bioassayed in mice for the presence of bradyzoites, using their resistance to pepsin as indicator. Six were studied by both methods. Based on these criteria, tachyzoites predominated in extraintestinal organs during the first 14 days after infection. They were found as early as 4 hr in mesenteric lymph nodes where their number reached 10(4) after 6 and 9 days; they were present after 1 day in all levels of the small intestine and after 6 days in the liver, lung, and blood. Bradyzoites were first detected 10 days after oocyst feeding; they predominated by the third week of infection and were present up to 41 days. Enteroepithelial stages were found histologically only in 2 cats, 24 and 41 days after inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

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TL;DR: Additional host granulocytic response, which included additional release of lysosomal enzymes into serum as well as phagocytosis of remnants of both sporocysts and developing cercariae, was elicited.
Abstract: The activity levels of serum acid phosphtase, aminopeptidase, and lysozyme in a Brazilian strain of Biomphalaria glabrata were ascertained at 1, 2, and 3 hr after mechanical wounding or injection with albumin on the 30th day postexposure to a compatible strain of Schistosoma mansoni miracidia and found to be elevated. Parallel transmission electron microscope studies on daughter sporocysts and developing cercariae at these time intervals revealed progressive disintegration of the parasites that was associated with increased numbers of host granulocytes abutting the sporocyst surfaces. Furthermore, host granulocytes were observed to have passed through eroded sporocyst walls and attacked developing cercarial embryos. It is proposed that the elevated levels of lysosomal hydrolases released from activated host granulocytes as a result of challenge altered the parasite's surfaces so that these were recognized as nonself. Consequently, additional host granulocytic response, which included additional release of lysosomal enzymes into serum as well as phagocytosis of remnants of both sporocysts and developing cercariae, was elicited.

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TL;DR: Results are suggestive of a role for IFN-gamma in protecting or limiting the development of E. tenella in their host cells and could be relevant to the control of these organisms and may be exploited for use with a coccidiosis vaccine.
Abstract: The effect of treating cultured Madin-Darby bovine kidney cells (MDBK) with recombinant bovine interferon-alpha 1 (IFN-alpha 1) or recombinant bovine interferon-gamma (IFN-gamma) on the intracellular development of Eimeria tenella was studied. Treatment of the MDBK cells with IFN alpha-1 for 24 hr before infection and for 48 hr after infection had no effect on the development of E. tenella. However, following the same treatment regime with serial dilutions of IFN-gamma induced a significant reduction in the number of total intracellular parasites (sporozoites, trophozoites, and meronts) compared to the untreated controls. Of these intracellular parasites, less than 30% had developed beyond the sporozoite stage. These results are suggestive of a role for IFN-gamma in protecting or limiting the development of E. tenella in their host cells. These results could be relevant to the control of these organisms and may be exploited for use with a coccidiosis vaccine.

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TL;DR: It is proposed that Peromyscus leucopus is more tolerant to the immature stages of the deer tick Ixodes dammini than is a less common host, the meadow vole, Microtus pennsylvanicus, to test the hypothesis that it adaptation to the immune and inflammatory reactions of the host.
Abstract: Ectoparasites such as ixodid ticks that remain attached to hosts for several days while feeding on blood are able to overcome the inflammatory and immune responses of some hosts and not others. The immature stages of the deer tick Ixodes dammini are found more frequently on the white-footed mouse, Peromyscus leucopus, than on other rodents. We propose that P. leucopus is more tolerant to I. dammini than is a less common host, the meadow vole, Microtus pennsylvanicus. To test this hypothesis, the distribution patterns and engorgement indices were determined for larval and nymphal I. dammini collected from wild-caught P. leucopus and M. pennsylvanicus. There were more immature ticks, which were more fully engorged, on P. leucopus than on M. pennsylvanicus. There were more and better engorged ticks on male than on female hosts. Laboratory studies on the number and weights of larval I. dammini collected off naive and previously exposed P. leucopus and M. pennsylvanicus support the results of the field study. Fewer larval ticks were recovered from previously exposed M. pennsylvanicus than P. leucopus, and the ticks weighed less. Larval and nymphal ticks aggregated among hosts in the study grid, and higher densities per male P. leucopus were correlated with higher engorgement indices, suggesting that immature I. dammini feed better at higher densities. The feeding success of I. dammini on its preferred host species might be due to its adaptation to the immune and inflammatory reactions of the host.