Complete development of Caryospora bigenetica (Apicomplexa: Eimeriidae) in vitro

Another African disease in Central Europa: Besnoitiosis of cattle. I. Light and electron microscopical study

The paper reports the first detection of besnoitiosis of cattle in Germany. Just 2 years after the first appearance of the African Bluetongue disease (BTD) of cattle in Central Europe, another African agent of disease has arrived in Germany. While it was proven that the BTD virus was transmitted (after its first appearance) by endemic midges of the genus Culicoides (C. obsoletus, C. pulicaris), nothing is known, how the infectious stages of Besnoitia besnoiti-a member of the so-called cyst-forming coccidia-found their way to a herd in Southern Germany. The infected animals showed all characteristic clinical symptoms of besnoitiosis such as hyposclerodermia, hyperkeratosis, alopecia, and whitish tissue cysts in subcutaneous tissues as well as in the cornea. These cysts had diameters of up to 3 mm and consisted of a dense outer layer (=secondary cyst wall), which surrounded a host cell, that had been enormously enlarged by an inner parasitophorous vacuole containing thousands of 7-9 x 2 mum sized, banana-shaped cyst merozoites (=cystozoites, bradyzoites).Their fine structure was identical to that of published stages of B. besnoiti. During cyst development, the nucleus of the host cell had been hypertrophied and had apparently undergone several divisions, since many flattened, but very large nuclei were seen in light and electron microscopy. Thus, this study proves the arrival of another serious agent of disease of ruminants in Central Europe-a fact which is especially important, since in this species, there is neither information on the way of transmission from animal to animal nor exists concrete information on an efficacious therapy or on the modalities of its import into Germany.

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.

Apicidin: a novel antiprotozoal agent that inhibits parasite histone deacetylase

A novel fungal metabolite, apicidin [cyclo(N-O-methyl-L-tryptophanyl-L -isoleucinyl-D-pipecolinyl-L-2-amino-8-oxodecanoyl)], that exhibits potent, broad spectrum antiprotozoal activity in vitro against Apicomplexan parasites has been identified. It is also orally and parenterally active in vivo against Plasmodium berghei malaria in mice. Many Apicomplexan parasites cause serious, life-threatening human and animal diseases, such as malaria, cryptosporidiosis, toxoplasmosis, and coccidiosis, and new therapeutic agents are urgently needed. Apicidin's antiparasitic activity appears to be due to low nanomolar inhibition of Apicomplexan histone deacetylase (HDA), which induces hyperacetylation of histones in treated parasites. The acetylation-deacetylation of histones is a thought to play a central role in transcriptional control in eukaryotic cells. Other known HDA inhibitors were also evaluated and found to possess antiparasitic activity, suggesting that HDA is an attractive target for the development of novel antiparasitic agents.

Experimental modes of Caryospora bigenetica (Apicomplexa: Eimeriidae) infection in swine and the effects of temperature and salinity on parasite infectivity in porcine tissue

Four crossbred pigs (Sus scrofa) were inoculated orally with Caryospora bigenetica oocysts derived from snake and mouse feces, and with C. bigenetica infected mouse tissue. One pig also was given i.m. injections of methylprednisolone acetate. All four pigs displayed clinical signs including erythema, edema, and lethargy. Caryocysts were observed histologically in numerous tissues including ear, tongue, jowl, shoulder, loin, intercostal, ham, hock, and feet. The four pigs each were butchered into six commercial cuts: shoulder, loin, side, ham, hock, and feet. Raw 10 g samples from each cut were bioassayed by pepsin digestion and s.c. inoculation into 12 Swiss-Webster mice (Mus musculus) and 12 cotton rats (Sigmodon hispidus). Seventeen of 24 mice and cotton rats exhibited clinical signs and C. bigenetica tissue infections. Remaining portions of the six commercial cuts were temperature or saline treated, and 10 g samples were bioassayed in 16 mice and 12 cotton rats. No clinical sign or tissue infection was observed in these animals. Our study presents evidence that swine can be infected with C. bigenetica by ingesting oocysts present in snake feces or mouse feces (following inoculation of mice with snake-derived oocysts) or by ingesting C. bigenetica infected rodent tissue, that endogenously produced C. bigenetica oocysts are not excreted in the feces of swine, and that C. bigenetica in pork can be rendered noninfective by freezing at -20 degrees C (-4 degrees F) for 21 days, frying at 84 degrees C (183 degrees F) for 17 min, microwaving at 88 degrees C (190 degrees F) for 17 min, grilling at 82 degrees C (180 degrees F) for 48 min, baking at 95 degrees C (203 degrees F) for 230 min, boiling at 100 degrees C (212 degrees F) for 60 min, or by curing at 4 degrees C (39 degrees F) for 20 days.

Ultrastructure of in vivo-produced caryocysts containing the coccidian Caryospora bigenetica (Apicomplexa: Eimeriidae)

A cotton rat was inoculated orally with oocysts of Caryospora bigenetica from the feces of a rattlesnake. Sixteen days later the rat was euthanized, and portions of the scrotum, foot pad and muzzle were processed for histological sections and transmission electron microscopy. Sporozoites within caryocysts had typical coccidian features such as an anterior and posterior refractile body, centrally located nucleus, micronemes, rhoptries, a conoid, a micropore near the anterior refractile body, a posterior pore, amylopectin granules, lipid bodies, a Golgi-like body, a mitochondrion and subpellicular microtubules. The infected host cell was spherical and surrounded by a fibrous wall-like covering, 0.35-1.00 microns thick. This outer covering, when viewed in stained histological sections, was periodic acid-Schiff (PAS)-positive.