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PubMed2002

Notes on coccidian phylogeny, based on the apicoplast small subunit ribosomal DNA.

We performed a phylogenetic analysis, based on the partial small subunit rRNA gene (SSU rRNA) sequences from 13 apicoplasts (including new sequences of Sarcocystis muris and Hyaloklossia lieberkuehni) and 16 other plastids, with cyanobacteria as an outgroup. The apicoplast sequences formed a highly supported monophyletic clade with two distinct clades, representing coccidia and haemosporidia, with coccidia divided into Eimeriidae and Sarcocystidae subclades. We confirmed the phylogenetic position of H. lieberkuehni within the Sarcocistidae, as a sister to the Toxoplasma/Neospora group. The coccidian plastid sequences appear to evolve slowly, while their homologues from haemosporidians are more rapidly evolving. We suggest that the higher evolutionary rate is reflected by the increase in the AT content and the possible reduction of the outer apicoplast membrane in some haemosporidians. Since the apicoplast SSU rRNA gene sequences, when compared with their nuclear homologues, offer a higher number of informative positions, they can be used for phylogenetic inference within the Apicomplexa.

Animals↗
PubMed2006

Study of proteins associated with the Eimeria tenella refractile body by a proteomic approach.

Refractile bodies (RB), whose function is still unknown, are specific structures of Eimeriidae parasites. In order to study their proteome, RB were purified from Eimeria tenella sporozoites by a new procedure using a reversible fixation followed by centrifugation. RB proteins were resolved by two-dimensional electrophoresis. Around 76 and 89 spots were detected on RB two-dimensional gels using gradients in the 3-10 and 4-7 range, respectively. RB proteins were located mainly between pH 5 and 7. RB gels were then compared with previously established maps of the entire sporozoite proteome. Proteins appearing in new spots were identified by mass spectrometry. Thirty protein isoforms were located in RB. Added to the already known RB proteins such as Eimepsin and SO7', the new RB proteins were defined as haloacid dehalogenase, hydrolase, subtilase, lactacte dehydrogenase or ubiquitin family proteins. The RB proteome analysis confirmed the hypothesis that this structure is a reservoir for proteins necessary to invasion but also suggests that RB have energetic and metabolic functions.

Animals↗
PubMed2005

Cloning and nucleotide sequencing of the second internal transcribed spacer of ribosomal DNA for three species of Eimeria from chickens in Taiwan.

Coccidiosis of chickens caused by protozoan parasites of the genus Eimeria (Coccidia: Eimeriidae) is an enteric disease that results in great economic losses throughout the world, including Taiwan. Using polymerase chain reaction (PCR) with primers specific for the second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA), three species of Eimeria, E. tenella, E. maxima, and E. acervulina have been successfully characterised from chickens in Taiwan. The sizes of PCR products from various isolates representing these three species were between 370 and 580 base pairs (bp). After cloning and sequencing of the PCR products, high nucleotide sequence identity (96.8-100%) was observed within a species. In addition, ITS-2 nucleotide sequences for E. tenella had higher homology (98.5-99.3%) than E. maxima (81.6-96.5%) when compared with appropriate sequences deposited in GenBank. To our knowledge, this is the first report of a 412-bp ITS-2 sequence for E. acervulina from chickens.

Animals↗
PubMed2001

A simple method of DNA extraction for Eimeria species.

A new, simple method is described for extracting DNA from coccidia (Eimeriidae) oocysts. In our hands this method works well for all Eimeria oocysts and, presumably, will work equally well for oocysts of other coccidia genera. This method combines the two steps of breaking oocyst and sporocyst walls, and dissolving the sporozoite membrane in one step. This greatly simplifies the currently used DNA extraction procedures for Eimeria species and overcomes the disadvantages of existing DNA extraction methods based on glass-bead grinding and sporozoite excystation procedures. Because all the procedures are done in a 1.5-ml microfuge tube, which minimizes the loss of DNA in the extraction procedures, this method is especially suitable for samples with small number of oocysts. In addition, this method directly lyses the oocyst and sporocyst walls as well as the sporozoite membrane in a continuous incubation; therefore, it does not require the sporozoites to be alive. The results of PCR experiments indicate that this method generates better quality of DNA than what the existing glass-bead grinding method does for molecular analysis, and is suitable for both large or small number (<10(2) oocysts) of living or dead oocyst samples.

Animals↗
PubMed2005

The influence of immunizing dose size and schedule on immunity to subsequent challenge with antigenically distinct strains of Eimeria maxima.

Eimeria maxima, the most immunogenic of the Eimeriidae that infect the chicken, is characterized by the presence of antigenic diversity within field isolates. In priming/challenge experiments immunity to homologous infection is essentially complete while immunity against challenge by a heterologous strain is often only partial. The phenotype "escape from immune protection" is known to be influenced by both host and parasite genotypes but the impact of varied immunization dose and schedule remains poorly documented. In this manuscript we report that an immunizing dose between 99.99%) protective immunity against challenge by 100 oocysts of a homologous strain. In contrast, complete immunity against a heterologous strain was never observed, although increasing the immunizing dose size did frequently reduce oocyst production arising from subsequent heterologous challenge. Differences in cross-protective immunizing capacity between two strains of E. maxima were evident as the H strain consistently stimulated a more potent protective immune response than the W strain. Similarly, increasing the number of immunizing doses of the E. maxima W strain (but not the H strain) increased immune protection against subsequent heterologous challenge. When combined with previously published data the results described here suggest that the E. maxima genome encodes a pool of antigens that are capable of stimulating an immune response cross-protective against more than one strain. These antigens supplement a separate restricted pool of antigens that are capable of stimulating stronger, but strain-specific, protective immune responses.

Animals↗
PubMed1977

Tazonomy of Toxoplasma.

After reviewing reports of the hosts, structure and life cycle of Toxoplasma, the genus is placed in the apicomplexan family Eimeriidae and the folllowing 7 species are recognized: Toxoplasma gondii (Nicolle & Manceaux) (type species) from about 200 species of mammals and birds, with oocysts in felids; Toxoplasma alencari (Da Costa & Pereira) from the frog Leptodactylus ocellatus; Toxoplasma brumpti Coutelen from the iguana Iguana tuberculata; Toxoplasma colubri Tibaldi from the snakes Coluber melanoleucus and Coluber viridiflavus; Toxoplasma hammondi (Frenkel & Dubey) (a new combination for Hammondia hammondi) from the house mouse with oocysts in the domestic cat; Toxoplasma ranae Levine & Nye from the leopard frog Rana Pipiens; and Toxoplasma serpai Scorza, Dagert & Iturriza Arocha from the toad Bufo marinus.

Animals↗
PubMed2000

Phylogenetic relationships of Hepatozoon (Apicomplexa: Adeleorina) based on molecular, morphologic, and life-cycle characters.

To evaluate higher-level affinities of Hepatozoon species within Apicomplexa, we sequenced the 18S rRNA gene from 2 parasites (Hepatozoon americanum and Hepatozoon canis) of dogs and 1 (Hepatozoon catesbianae) of bullfrogs. Sequences from other apicomplexans among the Sarcocystiidae, Eimeriidae, Theileriidae, Plasmodiidae, Cryptosporiidae, and Babesiidae, a Perkinsus species and 2 dinoflagellates were obtained from GenBank. Phylogenetic analysis indicated that Plasmodium, Cryptosporidium, and Hepatozoon form a monophyletic group distinct from representatives of other apicomplexan families. Although equivocal, our analysis indicated that Plasmodium and Cryptosporidium are sister taxa and that Hepatozoon is basal to them. To evaluate phylogenetic affinities among H. americanum, H. canis, and other species of Hepatozoon, we examined 18 morphologic and life-cycle features of 13 species currently assigned to Hepatozoon. This analysis indicates paraphyly of Hepatozoon (as currently arranged) because Hepatozoon lygosomarum was found most closely related to Hemolivia mauritanicum. These results, combined with results of previous studies, support elevating Hepatozoon to familial level (Hepatozoidae) as originally suggested by Wenyon in 1926. Both DNA sequence data and morphologic and life-cycle characters support a sister-group relationship between H. americanum and H. canis.

Animals↗
PubMed2001

Molecular phylogeny of the other tissue coccidia: Lankesterella and Caryospora.

Nearly complete sequences were obtained from the 18S rDNA genes of Eimeria falciformis (the type species of the genus), Caryospora bigenetica, and Lankesterella minima. Two clones of the rDNA gene from C. higenetica varied slightly in primary structure. Parsimony-based and maximum likelihood phylogenetic reconstructions with a number of other apicomplexan taxa support 2 major clades within the Eucoccidiorida, i.e., the isosporoid coccidia (consisting of Toxoplasma, Neospora, Isospora [in part], and Sarcocystis spp.) and a second clade containing Lankesterella and Caryospora spp., as well as the eimeriid coccidia (Cyclospora, Isospora [in part], and Eimeria spp.). Our observations suggest that Caryospora spp. may not belong in the family Eimeriidae but rather may be allied with the family Lankesterellidae with which they share molecular and life history similarities. This may be a third lineage of coccidian parasites that has independently evolved a unique heteroxenous transmission strategy.

Animals↗
PubMed2005

The genus Atoxoplasma (Garnham 1950) as a junior objective synonym of the genus Isospora (Schneider 1881) species infecting birds and resurrection of Cystoisospora (Frenkel 1977) as the correct genus for Isospora species infecting mammals.

Molecular and morphological data permit a rational subdivision of the paraphyletic Isospora into 2 apparently monophyletic groups of parasites, i.e., Isospora and Cystoisospora. Atoxoplasma was determined to be a junior objective synonym for Isospora. Tetrasporozoic, diplosporocystic oocysts possessing Stieda bodies in their sporocysts belong to Isospora (Eimeriidae) and have been described principally from the feces of birds. Tetrasporozoic, diplosporocystic oocysts without Stieda bodies in their sporocysts belong to Cystoisospora (Sarcocystidae).

Animals↗
PubMed2006

Description and phylogeny of a new species of Eimeria from double-crested cormorants (Phalacrocorax auritus) near Fort Gaines, Georgia.

The renal parasite Eimeria auritusi has caused several mortality events in double-crested cormorants (DCC; Phalacrocorax auritus) in the Midwest and southeastern United States. This parasite has only been detected during large-scale outbreaks, and its presence and prevalence in healthy populations of cormorants is unknown. In this study, 80 DCC were collected from the Chattahoochee River near Fort Gaines, Georgia, and examined for kidney and intestinal coccidia. Eighteen (22.5%) and 56 (70%) of the DCC were positive for E. auritusi and a new species of intestinal Eimeria, respectively. Oocysts of the new intestinal Eimeria species had a thin colorless wall, were ovoid with rare bumps on the outer surface, and measured 17.1 microm +/- 1.5 x 14.7 microm +/- 1.0 (16-18.5 x 13-17), with an average length:width ratio of 1.17 microm (1.03-1.29). A prominent micropyle (4-4.5 microm) was present, and a large oval-to-round polar body (2.5 microm) was located beneath the micropyle. Sporocysts were ovoid and measured 9.6 microm +/- 0.6 x 5.9 microm +/- 0.5 (8.5-10.5 x 5-6.5), with an average length:width ratio of 1.63 (1.3-1.82) with small stieda body present. Amplification and sequencing of a fragment of the 18S rRNA gene indicated that the 2 DCC Eimeria species and 2 Eimeria species from cranes were in a separate group from other Eimeriidae. These data indicate that E. auritusi and this new species of intestinal Eimeria are prevalent in this apparently healthy DCC population. The cause of renal coccidiosis outbreaks in other populations of cormorants is unknown but could be due to crowding or stress during the winter months or some other associated pathogen or immunosuppressor that might predispose individuals to clinical disease.

Animals↗
PubMedDate not supplied

Reevaluating the molecular taxonomy: is human-associated Cyclospora a mammalian Eimeria species?

Human-associated Cyclospora is a coccidian parasite that causes diarrheal disease. A reevaluation of the parasite's molecular taxonomy that takes into account newly published data for seven Eimeria species shows that Cyclospora belongs to the Eimeria clade (Eimeriidae family). The Cyclospora branch on the phylogenetic tree is between the branches of the eight avian and two mammalian Eimeria species that have been evaluated to date. Furthermore, preliminary results indicate that Cyclospora and Isospora belli, another coccidian parasite that causes diarrheal disease in humans, belong to different families. To improve our understanding of the taxonomy of human-associated Cyclospora, molecular evaluation of isolates of additional Cyclospora and Eimeria species is needed.

Animals↗
PubMed1999

An Eimeriid origin of isosporoid coccidia with Stieda bodies as shown by phylogenetic analysis of small subunit ribosomal RNA gene sequences.

Morphological and life cycle features of the tissue cyst-forming coccidia have been difficult to interpret in devising taxonomic classifications for the various genera. In this study, we amplified the full small subunit rRNA gene sequence of Isospora robini McQuistion and Holmes, 1988, and the partial sequence of Isospora gryphoni Olsen, Gissing, Barta, and Middleton, 1998 by PCR. Both of these species vary from Isospora species of mammals in having Stieda bodies on the sporocysts. The sequences were cloned and sequenced and were incorporated into an alignment with other Isospora species lacking Stieda bodies as well as with other coccidia. Maximum parsimony analysis of these sequences produced a single most parsimonious tree that placed I. robini and I. gryphoni in a clade containing various other eimeriid species. The Isospora species lacking Stieda bodies were in the sarcocystid clade. Similar results were found by maximum likelihood analysis. These findings indicate that the genus Isospora as defined by several authors is polyphyletic. Taxonomic changes to the genus Isospora would have to incorporate the 2 major clades found by molecular phylogenetic analysis. Isospora species with Stieda bodies should be classified in the family Eimeriidae, whereas those without Stieda bodies should remain in the family Sarcocystidae.

Animals↗
PubMedDate not supplied

[Distribution of coccidians (Sporozoa: Coccidiida) in various systematic groups of fishes].

There are about 250 coccidian species associated with fishes. They belong to 8 genera (Calyptospora, Cryptosporidium, Crystallospora, Eimeria, Epieimeria, Goussia, Isospora, Octosporella) and 3 families (Calyptosporidae, Cryptosporidiidae, Eimeriidae). Two genera are represented by great number of species associated with fishes: Eimeria--157 and Goussia--69 species. Most diverse fauna of coccidians was found in fishes of the class Actinopterigii; fishes of the class Elasmobranchii have significantly less number of coccidians. These parasites have never been recorded on the class Holocephali. Coccidian have been recorded in 55 orders of fishes. Within the Actinopterigii, the richest coccidian fauna is recorded from Cypriniformes and Perciformes. Accumulated data on host associations proves that coccidian species have mainly a restricted hosts specificity.

Animals↗
PubMedDate not supplied

[Evolutionary complication of life cycles in Coccidea (Sporozoa: Coccidea)].

Similar strategies to preserve a species were evolved independently in different groups of Coccidea. Polyenergid oocysts and tissue cysts are found in representatives of the orders Protococcidiida and Eimeriida. Hypnozoits are found in Karyolysus lacerate and Plasmodium vivax; transovarial transmission of parasites occurs in life cycles of Coccidea of the genera Karyolysis and Babesia. Formation of heteroxenity in groups of Coccidea apparently was developed by different ways and in different periods. In some groups (Cystoisospora, Toxoplasma, Aggregata, Atoxoplasma, Schelackia, Lankesterella, and Calyptospora), recent definitive hosts were initial hosts; in other groups (Sarcocystis, Karyolysus, Haemogregarina, Hepatozoon, Plasmodium, Haemoproteus, Leucytozoon, Babesiosoma, Theileria, and Babesia), intermediate hosts were initial hosts.

Animals↗
PubMed1988

A comparative study of the development of Eimeria nieschulzi in vitro under aerobic and reducing conditions.

Sporozoites of the rat coccidian, Eimeria nieschulzi Dieben, 1924 (Apicomplexa: Eimeriidae), were inoculated onto monolayers of normal rat kidney (NRK) fibroblasts and cultured either under aerobic (5% CO2/95% air) or reducing (desiccator jars modified into candle jars) conditions in RPMI-1640 supplemented with 5% fetal bovine serum, sodium bicarbonate, and antibiotics. Under aerobic conditions, first-generation meronts were observed at 2 days postinoculation (DPI) and, except for individual third-generation meronts that were seen at 5 and 6 DPI, no further development was noted. Under reducing conditions, however, first-generation meronts observed at 2-5 DPI underwent additional development to form second-generation meronts (3-5 DPI), third-generation meronts (3-7 DPI), and a small number of fourth-generation meronts (5-8 DPI). Both second- and third-generation meronts were abnormal, exhibiting gigantism although the merozoites produced appeared normal. The gradual degeneration of cell monolayers under reducing conditions prevented further observations beyond 8 DPI. These results suggest that atmospheric conditions play an important role in the development of E. nieschulzi and maintenance of reducing conditions may be one key to achieving enhanced development of some species of coccidia in vitro.

Aerobiosis↗
PubMed1977

Nomenclature of Sarcocystis in the ox and sheep and of fecal Coccidia of the dog and cat.

The nomenclature of Sarcocystis and related protozoan genera is reviewed, and modern diagnoses of the genera Isospora, Toxoplasma, Besnoitia, Sarcocystis, and Frenkelia in the coccidian family Eimeriidae are given. S cruzi (Hasselmann 1926) comb. n., S. hirsuta Moulé 1888, and S. hominis (Railliet and Lucet 1891) comb. n. are recognized in the muscles of the ox Bos taurus; S. ovicanis Heydorn, Gestrich, Melhorn, and Rommel 1975, and S. tenella Railliet 1886 are recognized in the muscles of the sheep Ovis aries; S. bigemina (Stiles 1891) comb. n., S. cruzi, S. ovicanis, S. bertrami Doflein 1901, S. miescheriana (Kühn 1865) Lankester 1882, I. ohioensis Dubey 1975, I. canis Nemeséri 1959, Isospora sp. n. Dubey, and Isospora sp. n. Trayser and Todd are recognized in dog (Canis familiaris) feces; and S. hirsuta, S. tenella, S. muris (Blanchard 1885) Labbé 1899, B. besnoiti (Marotel 1912) Henry 1913, Besnoitia sp. n. Frenkel, T. gondii (Nicolle and Manceaus 1908) Nicolle and Manceaux 1909, T. hammondi (Frenkel 1974) Levine and Nye 1976, I. rivolta (Grassi 1879) Wenyon 1923, and I. felis Wenyon 1923 are recognized in cat (Felis catus) feces. Hoareosporidium Pande, Bhatia, and Chauhan 1972 is considered a synonym of Sarcocystis.

Animals↗
PubMedDate not supplied

Invasion of different cell types by sporozoites of Eimeria species and effects of monoclonal antibody 1209-C2 on invasion of cells by sporozoites of several apicomplexan parasites.

Sporozoites of avian Eimeria species differed markedly in their ability to invade cells in vitro. Invasion by E. tenella and E. adenoeides was significantly greater in baby hamster kidney (BHK) and chicken cecal cell (CC) cultures than in primary chicken (PCK) or turkey kidney (PTK) cell cultures. Moreover, invasion of BHK cell cultures by E. adenoeides was significantly greater than that of other Eimeria species, and invasion by E. acervulina sporozoites was significantly lower. Monoclonal antibody 1209-C2 (MAb 1209-C2) reacted by immunofluorescent labeling (IFA) with refractile bodies of sporozoites of 5 species of Eimeria and Caryospora bigenetica, but not with sporozoites of Toxoplasma gondii, Hammondia hammondi, or Cryptosporidium parvum, which have no refractile bodies. The MAb also cross-reacted with formalin-fixed BHK, CC, turkey cecal (TC) cells, and PTK. Pretreatment of BHK cells with MAb 1209-C2 significantly reduced invasion of the cells by sporozoites of E. tenella, E. acervulina, E. meleagrimitis, and C. bigenetica, but did not alter invasion by T. gondii, C. parvum, or H. hammondia. Apparently, reactivity of MAB 1209-C2 with the sporozoites was required for inhibition of invasion despite the fact that the inhibition resulted from pre-treatment of the host cell. Conversely, although MAb 1209-C2 also reacted moderately with PTK and TC cells, pre-treatment of these cell cultures with the MAb did not inhibit invasion by either MAB 1209-C2-reactive or -nonreactive parasites. Collectively, the data indicated that refractile body antigens of sporozoites of Eimeria and Caryospora, which are recognized by MAb 1209-C2, may function in cellular invasion, but also suggest that cellular invasion is probably not mediated by interactions between the conserved epitopes in sporozoites and cultured host cells that are recognized by the MAb.

Animals↗
PubMed1994

Toxoplasma gondii: a monoclonal antibody that inhibits intracellular replication.

During its intracellular life cycle within the infected host cell, Toxoplasma gondii is able to undergo rapid asexual replication. Neither the mechanism by which the parasite initiates this process nor the requirements for maintaining it are understood. We produced a monoclonal antibody, 1B8, that identifies a parasite antigen of approximate M(r) 97 kDa as determined by SDS-PAGE. The epitope recognized by mAb 1B8 appears as a collection of vesicular structures scattered throughout the cell cytoplasm. When RH strain parasites are incubated with mAb 1B8 in the absence of serum complement, parasite growth is inhibited by > 90% as determined by radioisotope incorporation. Both attachment and invasion assays show that neither of these parasite-host cell interactions are inhibited by the mAb. However, a marked reduction in the number of intracellular rosettes was observed following mAb treatment of the parasites. Viable extracellular parasites are able to endocytose mAb 1B8. Once within the parasite cytosol the antibody recognizes the vesicular structures similar to those observed with fixed parasites. Immunofluorescence assays with Besnoitia jellisoni and Plasmodium falciparum show that the epitope recognized by mAb 1B8 is conserved among Coccidiae but not the kinetoplastid Leishmania.

Animals↗