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  • 1
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Scanning and electron microscopy was used to study the pathogenesis that occurred in mouse epithelial cells that had been penetrated byEimeria papillata sporozoites. Optimal penetration of parasites injected into nonligated and ligated mouse intestine was found to occur at 4–15 min post-inoculation. During initial penetration, the parasite caused disruption of the microvilli of the intestinal cells, which led to detachment of the microvilli from the plasma membrane of the penetrated cell. Host cells penetrated by the parasite showed extensive destruction of the internal cellular organization together with blebbing of host-cell cytoplasm and release of internal organelles such as mitochondria. Ultimately, the penetrated cells completely broke down, leaving vacuolated areas next to ultrastructurally normal epithelial cells.
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  • 2
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A cross-reactive monoclonal antibody (mAb), designated 1205, was used to study redistribution, parasitophorous vacuole (PV) incorporation, and in situ antigen production during the intracellular parasite development ofEimeria acervulina andE. tenella. Western-blot analysis of sporozoite preparations showed that the mAb recognized antigenic bands at 55 and 80 kDa. Indirect immunofluorescent antibody (IFA) labeling of sporozoites produced an internal dot pattern. Immunogold electron microscopy (IM) showed labeling of dense granules within sporozoites. The IFA pattern changed to a general-internal label in immature schizonts followed by a surface-tip pattern in mature merozoites both in vitro and in vivo. IM of the asexual stages revealed the same labeling pattern for the in vivo development of both species, and labeling of rhoptries was seen. In vitro, the PV membrane together with amorphous material within the PV was labeled by IFA during schizont development forE. tenella. No IM labeling of either the PV membrane or material within the PV was observed. Sexual stages seen in vivo for both species had the general-internal IFA pattern.
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  • 3
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The use of a gel-immunization technique with Immucox vaccination was compared and evaluated against other immunization methods in battery and floor-pen immunization trials. Gel immunization was found to be superior to immunization by gavage, by spray cabinet, or by the conventional delivery method of Immucox in a battery trial. Significantly enhanced protection as measured by weight gain, coupled with the establishment of a more uniform primary immunizing infection as evidenced by greater intestinal lesions and increased oocyst shedding, was seen in gel-immunized birds. In addition, cross-protective battery trials determined that the strain of Eimeria maxima found in the Immucox vaccine failed to elicit protection against a recent field isolate of E. maxima as measured by average weight gain and lesion scores. A reformulation of the Immucox vaccine that included the field isolate of E.␣maxima was required to elicit a protective immune response against challenge by the field strain. A floor-pen experiment demonstrated that gel immunization of 1-day-old roaster chickens resulted in performance parameters of average weight gain, average bird weight, and feed conversion that did not differ significantly from those recorded for medicated nonimmunized birds.
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  • 4
    ISSN: 1432-1955
    Keywords: AbbreviationsMBHA 4-Methyl benzhydral amine Peptidyl-MIMs Synthetic peptidyl membrane-interactive molecules ; pMIMs Peptidyl-MIMs ; PBEL Parasite Biology and Epidemiology Laboratory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This study examined the lytic effect of seven different synthetic peptidyl membrane-interactive molecules (Peptidyl-MIMs) on sporozoites of five different species of Eimeria infecting chickens and merozoites of two different species that infect chickens. All Peptidyl-MIMs (pMIMs) demonstrated antiparasitic effects at concentrations of 1–50 μM during incubation periods varying from 1 to 20 min. In addition, electron microscopy showed that ultrastructural degeneration of the pellicle of sporozoite stages of the parasites occurred within 5–10 min of exposure to 5-μM concentrations of three different pMIMs. Pore-like openings were seen in the pellicle of the sporozoites at the ultrastructural level, which indicated that the pMIMs had the same mechanism of action on the parasites as that reported from studies done on bacteria. A reduction in lesion scores was seen in chickens treated orally with 10-, 50-, or ␣␣␣␣␣75-μM concentrations of two different proteolytic stabilized (methylated) pMIMs after challenge with three different species of avian coccidia in battery-cage trials. Collectively these data indicate that pMIMs may be useful in the control of coccidiosis in poultry.
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  • 5
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The pathology that occurs in mouse embryonic brain (MEB) cells that have been penetrated by sporozoites ofEimeria papillata was studied by light and electron microscopy. At the light microscopy level the greatest number of intracellular parasites was seen at 15 and 45 min postinoculation (PI). The monolayer of MEB cells had begun to round up by 45 min PI, and by 60 min PI most of the cells were stripped from the coverslip. Little ultrastructural damage was seen in MEB cells just penetrated by the parasites at 15 min PI, and no host cell membrane was seen around the sporozoites that had just entered the cells. Flexing and bending of the sporozoites within the MEB cell caused vacuolization of cell cytoplasm and in some cases rupture of host cell membrane. Sporozoites leaving the host cells at 15 min PI caused a rupture of the host cell membrane at the apical end of the parasite, and both host cell membrane and cytoplasm were attached to the surface of the parasite. MEB cells still attached to coverslips at 45 min PI demonstrated complete degeneration.
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  • 6
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Transmission electron microscopy was used to study the in vitro development ofEimeria tenella in a novel established avian-derived cell line (designated CEV-1/F7) used for antigen production in chicken immunization studies. Sporozoites ofE. tenella were inoculated onto cell monolayers and the cells were fixed at 24-h intervals. Large numbers of intracellular sporozoites were seen at 24 h postinoculation (p.i.), and trophozoites were identified at 24–48 h p.i. Immature schizonts, some with budding merozoites, were seen by 48 h p.i. At 72–96 h p.i., immature and mature schizonts and extracellular merozoites were observed. No merozoite invasion occurred, but immature second-generation schizogony was seen in parasitophorous vacuoles of first-generation schizonts. No further development occurred and degeneration of most schizonts was seen by 120–144 h p.i. The results confirmed synchronous development ofE. tenella until 48 h p.i., followed by asynchronous development and ultrastructural degeneration with increased incubation time.
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  • 7
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A study of development of Eimeriatenella in chickens fed high n-3 fatty acids (n-3FA) diets showed ultrastructural degeneration of both asexual and sexual parasite stages. Abnormal shedding of asexual and sexual parasite developmental stages into the cecal lumen was also observed. Ultrastructural degeneration was characterized by cytoplasmic vacuolization, chromatin condensation within the nucleus, a lack of parasitophorous vacuole delineation, and, in some cases, a complete loss of parasite ultrastructural organization. The results of this study indicate that diets high in n-3FA may be useful in the control of avian coccidia.
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  • 8
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Primary turkey kidney cells and Eimeria meleagrimitis sporozoites were treated with cationized ferritin (CF) or neuraminidase (NANase), and the effects on the invasion of the cells by the sporozoites were measured. Cultures of host cells pretreated with either compound contained significantly fewer intracellular sporozoites than did control cultures. There was little additive effect if cultures were first treated with NANase and then with CF. In contrast, pretreatment of sporozoites with CF or low concentrations of NANase had no effect on invasion. The inhibition of invasion was apparently due to an interaction between treatment substances and host cell surface rather than to direct effect on the sporozoites. The CF bound to the randomly distributed anionic sites on the surfaces of both host cells and sporozoites and then rapidly aggregated. Sporozoites, probably in the process of invading cells, were invariably found with the conoid in close association with aggregates of CF on the host cell membrane. The CF on the sporozoites was apparently shed before or during invasion because all intracellular sporozoites were completely devoid of the label.
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