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PubMed1997

Eimeria schmidti n. sp. (Apicomplexa: Eimeriidae) from the sandy fringe-toed lizard (Acanthodactylus schmidti) in Saudi Arabia.

Eimeria schmidti n.sp. is described from the gall bladder of Acanthodactylus schmidti from Al-Thomama area in the central region of Saudi Arabia. Sporulated oocysts are ellipsoid 31.2 x 23.3 (26.9-36.4 x 21.2-26.0). Oocyst wall is smooth, greenish yellow, 1.31 (1.16-1.41) um thick and two-layered. Micropyle, polar granule and oocyst residuum are absent. Sporocysts are ellipsoid 12.6 x 9.3 (10.9-14.1 x 7.6-10.0) um. Sporocyst residuum is present. The sporocysts lack a stieda body. Sporozoites are banana shaped blunt at one end and tapered at the second end. Eimeria species from Lacertidae are compared.

Animals↗
PubMed1997

Vipera berus and V. ammodytes (Serpentes:Viperidae) represent new host for Caryospora simplex (Apicomplexa:Eimeriidae) in Europe.

During a survey of the coccidian parasites of reptiles, caryosporan oocysts wee found in the faeces of wild and captive European viperid snakes Vipera berus (L.) and V. ammodytes (L.). Thirty two of 37 examined V. berus (86%) and 9 of 17 examined V. ammodytes (53%) specimens were found to be passing caryosporan oocysts. Morphological characters of all caryosporan isolates were identical and fitted well with the description of Caryospora simplex Léger, 1904. Experimental inoculation of severe combined immunodeficient (SCID) mice with seven isolates of C. simplex from V. berus or V. ammodytes confirmed the heteroxenous life cycle pattern, for the first time for isolates of evidently European origin. Caryosporan developmental stages were observed in the connective tissues of the nose, cheeks, ear and scrotum in all inoculated SCID mice. V. berus and V. ammodytes represent new hosts for C. simplex. The present paper represents the first widely based report on coccidian parasites of the genus Caryospora Léger in European viperids. Our findings indicate a wide distribution of C. simplex throughout the range of distribution of snakes of the genus Vipera.

Animals↗
PubMed1997

Two new species of Eimeria (Apicomplexa, Eimeriidae), from local chickens (Gallus domesticus) in Saudi Arabia.

In this study, two new species of Eimeria parasitizing domestic fowl (Gallus domesticus) are described. Species data were recorded as follow: Eimeria jeddahensis sp. n. with ovoidal occysts 23.5-29.2 x 17.5-22.4 (25.78 +/- 0.357 x 20.32 +/- 0.33) microns, with smooth single layered wall; bilobed polar granule and micropyle present. Sporocysts elongated ovoidal 10-13.5 x 6.3-8.0 (12.03 +/- 0.135 x 7.10 +/- 0.070) microns with a thick, knob like Stieda body and residuum. Eimeria waeli sp. n. with ellipsoidal oocysts 26.5-31.0 x 23.5-27.0 (28.30 +/- 0.327 x 25.30 +/- 0.278) microns with a double-layered wall; polar granule and micropyle present. Sporocysts ovoidal 13.5-16.0 x 7.0-9.5 (14.67 +/- 0.135 x 8.32 +/- 0.162) microns with distinct Stieda body and residuum. The host bird belongs to order Galliformes.

Animals↗
PubMed1997

Margolisiella kabatai gen. et sp. n. (Apicomplexa: Eimeriidae), a parasite of native littleneck clams, Protothaca staminea, from British Columbia, Canada, with a taxonomic revision of the coccidian parasites of bivalves (Mollusca: Bivalvia).

Two of 98 native littleneck clams, Protothaca staminea Conrad, from Cooper's Cove, Sooke Basin were infected with an eimeriorin coccidian parasite. Merogonic gamontogonic and sporogonic development were observed in renal tubular epithelial cells. Sporulation of the oocysts occurred within the host. Mature oocysts were spherical mean 41 microns (range 30-44), and contained about 32 subspherical sporocysts (9 x 10 microns), each of which contained 4 sporozoites. Spherical 19 microns (18-20), cyst-like structures and smaller multinucleate bodies, some of which resembled sporocysts, were also seen. A review of the coccidian parasites of bivalves led to the erection of the new genus, Margolisiella (family Eimeriidae Minchin, 1903) to accommodate M. kabatai sp. n., the parasite in Protothaca staminea described herein. Four previously described monoxenous species (Pseudoklossia patellae Debaisieux, P. chitonis Debaisieux, P. tellinovum Buchanan and P. haliotis Friedman, Gardner, Hedrick, Stephenson, Cawthorn et Upton) were also transferred to the new genus. The 2 remaining possibly heteroxenous species (P. pelseneeri Léger and P. glomerata Léger et Duboscq) were retained in the genus Pseudoklossia Léger et Duboscq (family Aggregatidae Labbé, 1899).

Animals↗
PubMedDate not supplied

[The interrelationships of the coccidian Cryptosporidium parvum (Apicomplexa: Sporozoa) with the cells of the immune system in the mammalian host].

By means of an electron microscopic study of the intestine in young rats infected with Cryptosporidium parvum we observed a mass migration of immunocompetent cells of the host (eosinophils, neutrophils and macrophages) into the lumen of intestine. Some lymphocytes were also observed. Immunocompetent cells (except lymphocytes) included inside phagosomes with different endogenic states of C. parvum. Macrophages with typical extracytoplasmic parasitophorous vacuoles formed by C. parvum were also observed in the intestine lumen. Almost all stages of C. parvum could be observed on a surface of such macrophages. However, we did not find in lamina propria of intestine villi any macrophages with parasites. The place of macrophages infection is unknown. We suggest that surviving of C. parvum in macrophages is principally possible.

Animals↗
PubMed1998

A new coccidian parasite (Apicomplexa: Eimeriidae) from the legless lizard Diplometopon zarudnyi (Amphisbaenia: Trogonophidae) in Saudi Arabia.

Large numbers of coccidian oocysts belonging to the genus Isospora were obtained from the intestinal contents of ten legless lizards Diplometopon zarudnyi collected from eastern region, Saudi Arabia. The oocysts are spherical to subspherical, 33.3 x 30.9 (28.6-35.2 x 26.8-32.7) microns with a bilayered wall 1.4 (1.3-1.6) microns thick. Micropyle, polar granule and oocyst residuum are absent. The sporocysts are ellipsoid, 20.1 x 13.8 (17.5-22.3 x 12.2-15.4) microns. A sporocyst residuum, stieda and substieda bodies are present. Sporozoites are banana shaped, blunt at one end and tapered at the other and containing spherical anterior and posterior refractile bodies of the same size. Since this Isospora sp. does not resemble, any other species of Isospora previously described from lizards of the genus Diplometopon, it has been named Isospora diplometoponi n.sp. after the host generic name.

Animals↗
PubMed1998

The life history and host specificity of Hepatozoon clamatae (Apicomplexa: Adeleorina) and ITS-1 nucleotide sequence variation of Hepatozoon species of frogs and mosquitoes from Ontario.

The life cycle of an intraerythrocytic hemogregarine, Hepatozoon clamatae, was studied in green frogs (Rana clamitans melanota), bullfrogs (Rana catesbeiana), northern leopard frogs (Rana pipiens), and in the mosquito, Culex territans. Gametogenesis, fertilization, and sporogony occurred within cells of the Malpighian tubules of laboratory-reared Cx. territans that had fed on naturally infected frogs. Mature oocysts containing hundreds of sporocysts were observed in mosquitoes 30 days postfeeding. Each sporocyst enclosed 4 sporozoites. Merozoites appeared in the peripheral circulation of laboratory-reared bullfrogs, green frogs and leopard frogs that had been fed sporocysts 35-70 days previously. Attempts to infect American toads (Bufo americanus) and blue-spotted salamanders (Ambystoma laterale) were not successful. Gamonts of this parasite induced nuclear fragmentation or segmentation in host erythrocytes. The life cycle, morphological, and morphometric features of H. clamatae are compared with H. catesbianae, a similar species that also infects ranids. Nucleotide sequence analysis of the internal transcribed spacer region (ITS-1) of these sympatric species revealed that only 6 nucleotide sites of the 129 base pairs of this region were variable among 4 isolates of H. clamatae and 2 isolates of H. catesbianae. A redescription of H. clamatae is presented based on data from this study and from the original description by Stebbins in 1905.

Animals↗
PubMed1998

Atoxoplasma (Apicomplexa: Eimeriorina: Atoxoplasmatidae) in the greenfinch (Carduelis chloris).

Merozoites of an Atoxoplasma species were present within parasitophorous vacuoles in the cytoplasm of leucocytes in the blood vessels in the small intestine of the greenfinch (Carduelis chloris). The merozoites indented the nucleus of the leucocytes. Merozoites, macrogametes, and microgamonts were present in the epithelial cells of the intestines. No merogony was observed. Experiments provided circumstantial evidence linking disporocystid-octozoic oocysts with the blood and intestinal infections.

Animals↗
PubMedDate not supplied

[Newly established causes of diarrhea: the protozoan Cyclospora cayetanensis (Coccidia, Apicomplexa)].

UNLABELLED: Coccidia Cyclospora cavetanesis has been considered a saprophytic or accidental infection without special medical significance until 1984. However, epidemics of diarrhea first in Peru and later in USA. Haiti and Nepal have aroused interest in pathogenic characteristics of this parasite and diseases it causes. The study first deals with biological cycle of parasite development as well as clinical picture and treatment, diagnostics and epidemiology of this parasitic disease. CLINICAL PICTURE: On average the incubation period was 2-11 days with frequent stools (3 or more times a day) without blood or mucus and with tendency for recurrence. The prodromal phase is similar to influenza. It may last several weeks especially in immunodeficient persons (especially patients with AIDS). Trimethoprim (160 mg) and sulfamethoxazole (800 mg) is the treatment of choice, twice a day during a 7 day period, whereas in immunodeficient patients greater doses are necessary during a few weeks, but in such cases individual treatment planning is required. Laboratory diagnosis is made on the basis of microscopic examination of native preparation from the stool, especially if stool concentration procedure is used due to small number of oocysts in the stool. As this method does not provide identification of species, numerous staining methods are recommended (modified Ziehl-Neelsen method, Carbol-Fuchsin and safranine). Epidemiology is still unclear. It is considered that there are two sources of infection: contaminated drinking water and fruits. The disease has a seasonal character and the highest incidence is recorded in late spring and summer months. The infection is caused only by sporozoites developed by sporulation of oocysts under environmental conditions excluding the possibility of direct transmission from one person to another. It is to be expected that further investigations will give answers to numerous questions still open.

AIDS-Related Opportunistic Infections↗
PubMed1998

Exogenous stages of Eimeria bemricki n. sp. (Apicomplexa: Eimeriidae) from the great gray owl, Strix nebulosa (Foster).

Exogenous stages of a new species of Eimeria are described from feces of a captive great gray owl, Strix nebulosa, held at the Gabbert Raptor Center, University of Minnesota, St. Paul, Minnesota. Oocysts (n = 100) of Eimeria bemricki are spherical to subspherical, 19.2 x 19.0 (21.5-16.0 x 21.0-16.0) microm, with ovoidal sporocysts (n = 100), 10.0 x 6.5 (12.0-7.0 x 7.0-5.5) microm and sporozoites (n = 20), 8.2 x 3.2 (6.8-10.1 x 2.5-3.9) microm. Stieda bodies, substieda bodies, polar bodies, and sporocyst residua are present, but micropyle, oocyst residuum, and parastieda bodies are absent. Three refractile bodies are contained in each sporozoite.

Animals↗
PubMed1998

Description of a new Neospora species (Protozoa: Apicomplexa: Sarcocystidae).

Neospora hughesi n. sp. was isolated from the central nervous system tissue of an adult equine (Equus caballus) from California. The tachyzoites are crescent-shaped, approximately 2 x 5 microm (1.8-3.0 x 4.0-7.0 microm), with characteristic apical complex structures consisting of an anterior polar ring, conoid, numerous rhoptries filled with a uniform electron-dense material, and 22 microtubules extending posteriorly from the polar ring. Comparison of N. hughesi to canine and bovine Neospora caninum isolates showed phenotypic differences in immunoreactive proteins. Molecular analysis of the small subunit ribosomal RNA gene revealed no differences in the nucleotide sequence between N. hughesi and N. caninum isolates examined. However, the internal transcribed spacer I region revealed 7 nucleotide base differences between N. hughesi and N. caninum isolates (CN1 and BPA1) analyzed in this study. The existence of nucleotide base differences in the internal transcribed spacer regions suggests that this region may be a genetic marker for discriminating species within the genus Neospora. The ultrastructural, antigenic, and molecular data support distinction of N. hughesi as a new species, separate from N. caninum, the only recognized species in this genus.

Animals↗
PubMed1998

A new Eimeria species (Apicomplexa: Eimeriidae) infecting Onychomys species (Rodentia: Muridae) in New Mexico and Arizona.

Fecal samples from 3 species of Onychomys (Rodentia: Muridae) captured in New Mexico and Arizona were examined for coccidia. Six of the 59 (10%) were infected with a new species of Eimeria. Sporulated oocysts (n = 105) of this new species are subspheroidal, 17.4 x 16.1 (14-21 x 13-19) microm, with ellipsoidal sporocysts 10.4 x 5.7 (9-12 x 5-8) microm. This species occurred in 3 of 24 (13%) Onychomys arenicola, 2 of 31 (6%) Onychomys leucogaster from New Mexico, and 1 of 4 (25%) Onychomys torridus from Arizona. Isolates recovered from O. leucogaster and O. torridus were inoculated into O. leucogaster (n = 5) and produced infections with a prepatent period of 7 days and a patent period of 7-23 days.

Animals↗
PubMed2000

Cryptosporidium parvum appears to lack a plastid genome.

Surprisingly, unlike most Apicomplexa, Cryptosporidium parvum appears to lack a plastid genome. Primers based upon the highly conserved plastid small- or large-subunit rRNA (SSU/LSU rRNA) and the tufA-tRNAPhe genes of other members of the phylum Apicomplexa failed to amplify products from intracellular stages of C. parvum, whereas products were obtained from the plastid-containing apicomplexans Eimeria bovis and Toxoplasma gondii, as well as the plants Allium stellatum and Spinacia oleracea. Dot-blot hybridization of sporozoite genomic DNA (gDNA) supported these PCR results. A T. gondii plastid-specific set of probes containing SSU/LSU rRNA and tufA-tRNA(Phe) genes strongly hybridized to gDNA from a diverse group of plastid-containing organisms including three Apicomplexa, two plants, and Euglena gracilis, but not to those without this organelle including C. parvum, three kinetoplastids, the yeast Saccharomyces cerevisiae, mammals and the eubacterium Escherichia coli. Since the origin of the plastid in other apicomplexans is postulated to be the result of a secondary symbiogenesis of either a red or a green alga, the most parsimonious explanation for its absence in C. parvum is that it has been secondarily lost. If confirmed, this would indicate an alternative evolutionary fate for this organelle in one member of the Apicomplexa. It also suggests that unlike the situation with other diseases caused by members of the Apicomplexa, drug development against cryptosporidiosis targeting a plastid genome or metabolic pathways associated with it may not be useful.

Animals↗
PubMed2004

Toxoplasma gondii: the model apicomplexan.

Toxoplasma gondii is an obligate intracellular protozoan parasite which is a significant human and veterinary pathogen. Other members of the phylum Apicomplexa are also important pathogens including Plasmodium species (i.e. malaria), Eimeria species, Neospora, Babesia, Theileria and Cryptosporidium. Unlike most of these organisms, T. gondii is readily amenable to genetic manipulation in the laboratory. Cell biology studies are more readily performed in T. gondii due to the high efficiency of transient and stable transfection, the availability of many cell markers, and the relative ease with which the parasite can be studied using advanced microscopic techniques. Thus, for many experimental questions, T. gondii remains the best model system to study the biology of the Apicomplexa. Our understanding of the mechanisms of drug resistance, the biology of the apicoplast, and the process of host cell invasion has been advanced by studies in T. gondii. Heterologous expression of apicomplexan proteins in T. gondii has frequently facilitated further characterisation of proteins that could not be easily studied. Recent studies of Apicomplexa have been complemented by genome sequencing projects that have facilitated discovery of surprising differences in cell biology and metabolism between Apicomplexa. While results in T. gondii will not always be applicable to other Apicomplexa, T. gondii remains an important model system for understanding the biology of apicomplexan parasites.

Animals↗
PubMedDate not supplied

Re-examining alveolate evolution using multiple protein molecular phylogenies.

Alveolates are a diverse group of protists that includes three major lineages: ciliates, apicomplexa, and dinoflagellates. Among these three, it is thought that the apicomplexa and dinoflagellates are more closely related to one another than to ciliates. However, this conclusion is based almost entirely on results from ribosomal RNA phylogeny because very few morphological characters address this issue and scant molecular data are available from dinoflagellates. To better examine the relationships between the three major alveolate groups, we have sequenced six genes from the non-photosynthetic dinoflagellate, Crypthecodinium cohnii: actin, beta-tubulin, hsp70, BiP, hsp90, and mitochondrial hsp10. Beta-tubulin, hsp70, BiP, and hsp90 were found to be useful for intra-alveolate phylogeny, and trees were inferred from these genes individually and in combination. Trees inferred from individual genes generally supported the apicomplexa-dinoflagellate grouping, as did a combined analysis of all four genes. However, it was also found that the outgroup had a significant effect on the topology within alveolates when using certain methods of phylogenetic reconstruction, and an alternative topology clustering dinoflagellates and ciliates could not be rejected by the combined data. Altogether, these results support the sisterhood of apicomplexa and dinoflagellates, but point out that the relationship is not as strong as is often assumed.

Animals↗
PubMed1994

The phylogeny of Neospora caninum.

Morphological studies by electron microscopy on the protozoan Neospora caninum have shown that this organism possesses a subcellular structure typical of parasites classified in the family Sarcocystidae, subclass Coccidiasina of the phylum Apicomplexa. Using a strategy based on DNA sequence analysis of products derived by asymmetric PCR to determine the nucleotide sequences, we have tested the validity of this classification by comparing the small subunit ribosomal RNA (18S rRNA) gene sequences of N. caninum with those of other parasitic protozoa classified in the phylum Apicomplexa. The results of this analysis confirm the placing of N. caninum in the family Sarcocystidae and place it as a sister group to Toxoplasma gondii in the phylum Apicomplexa.

Animals↗
PubMed2003

Apicoplast fatty acid biosynthesis as a target for medical intervention in apicomplexan parasites.

New chemotherapies for human and animal apicomplexan infections are needed as a component of future strategies to deal with these diseases. An extensive search for new treatments exploring the unique developmental physiology, metabolism and molecular structures of Apicomplexa is under way. The description of the full complement of about 5,300 Plasmodium falciparum genes and fast growing sequence databases for other Apicomplexa allow reconstruction of metabolic pathways of these parasites and thus accelerate identification and biochemical analysis of potential targets. The apicoplast de novo fatty acid biosynthetic pathway shows great potential as a target for small-molecule inhibitors in a stand-alone or combination chemotherapy. Three enzymatic activities, acetyl-CoA carboxylase, beta-ketoacyl-ACP synthase and enoyl-ACP reductase, respond to inhibitors previously identified for bacteria and plants, and deserve to be explored in depth. In this connection, screening systems have been established to seek more potent and specific antiparasitic compounds that are harmless to the host. To this end the interconnections of fatty acid biosynthesis in Apicomplexa with other metabolic and cellular processes must be investigated.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗