Studies on the Storage Polysaccharides of the Coccidia Eimeria bovis and Eimeria stiedai

Polysaccharides have been isolated from Eimeria bovis and E. stiedai by the use of alkali. The purified polysaccharides stain purple with iodine and have been shown by chemical and enzymic means to be amylopectin. The storage amylopectins of these coccidia differ slightly from typical plant amylopectins in their fine structure.     

Speciation studies with Eimeria acervulina and Eimeria mivati.

Eimeria mivati was described as a new species of chicken coccidia in 1964 by Edgar and Seibold, but recently some British workers have relegated its status to that of a variety of Eimeria acervulina. Using strains supplied by Dr. Edgar, we have prepared lines of E. acervulina resistant to methyl benzoquate, sulfaquinoxaline and robenidine and a line of E. mivati resistant to methyl benzoquate. Genetic transfer of resistance between the various lines of E. acervulina to produce doubly-resistant coccidia has been demonstrated, but no such transfer could be obtained between E. mivati resistant to methyl benzoquate and the resistant lines of E. acervulina. Although some immunological relationship between E. acervulina and E. mivati has been demonstrated, we conclude that this failure of the 2 organisms to interbreed lends support to the status of E. mivati as a distinct species.     

Enzyme cytochemical observations on the tissue stages of the life cycle of Eimeria acervulina and Eimeria necatrix

Cytochemical studies concerning the presence and distribution of various enzymes in the tissue stages of the life cycle of Eimeria acervulina and E. necatrix have been undertaken.Acid and alkaline phosphatases as well as ATPase (pH 7·2) were found to be present in all the stages of the life cycles examined, the latter enzyme being very strong in the plastic granules of the macrogametocytes and in the inner membrane of the oocyst wall. The reaction for all three enzymes was observed in the cytoplasm but not the nucleus. Non-specific esterase and glucose-6-phosphatase were also found in all stages examined, the latter occurring in greater amounts in stages where deposition of glycogen (amylopectin) was pronounced. Succinic dehydrogenase occurred only in the second generation schizonts and merozoites of E. necatrix and in the formed oocysts of both species. No reaction for β-glucuronidase or leucine naphthylamidase was apparent in any stage, although a slight reaction for leucine naphthlyamidase was seen in the second generation merozoites of E. necatrix lying free in the intestinal lumen.The presence and distribution of these enzymes and their possible function were discussed.     

Bacterial flora in the alimentary tract of chickens infected with Eimeria brunetti and in chickens immunized with Eimeria maxima and cross-infected with Eimeria brunetti

Differential bacterial counts were made on the intestinal and caecal contents of chickens after inoculation with a standard dose of 320 000 freshly sporulated oocysts of Eimeria brunetti.     

The genome of Eimeria spp., with special reference to Eimeria tenella--a coccidium from the chicken

Eimeria spp. contain at least four genomes. The nuclear genome is best studied in the avian species Eimeria tenella and comprises about 60 Mbp DNA contained within ca. 14 chromosomes; other avian and lupine species appear to possess a nuclear genome of similar size. In addition, sequence data and hybridisation studies have provided direct evidence for extrachromosomal mitochondrial and plastid DNA genomes, and double-stranded RNA segments have also been described. The unique phenotype of "precocious" development that characterises some selected lines of Eimeria spp. not only provides the basis for the first generation of live attenuated vaccines, but offers a significant entrée into studies on the regulation of an apicomplexan life-cycle. With a view to identifying loci implicated in the trait of precocious development, a genetic linkage map of the genome of E. tenella is being constructed in this laboratory from analyses of the inheritance of over 400 polymorphic DNA markers in the progeny of a cross between complementary drug-resistant and precocious parents. Other projects that impinge directly or indirectly on the genome and/or genetics of Eimeria spp. are currently in progress in several laboratories, and include the derivation of expressed sequence tag data and the development of ancillary technologies such as transfection techniques. No large-scale genomic DNA sequencing projects have been reported.     

Problems in the identification of species of Eimeria

The paper is concerned with the principles upon which coccidia of the genus Eimeria may be characterized. Reference strains for comparative purposes usually are not available and the limitations of morphological data for speciation are discussed. The value of other parameters are considered such as host and site specificity, pathogenicity, immunological specificity, pre-patent period, sporulation time, enzyme variation, and DNA buoyant density. The weight afforded to each of these parameters for specific identification may vary according to the parasite and host studied. Determinations of physiological and behavioral characteristics that are now becoming available should be included in species definitions wherever possible.     

Problems in the Identification of Species of Eimeria

ABSTRACT. The paper is concerned with the principles upon which coccidia of the genus Eimeria may be characterized. Reference strains for comparative purposes usually are not available and the limitations of morphological data for speciation are discussed. The value of other parameters are considered such as host and site specificity, pathogenicity, immunological specificity, pre-patent period, sporulation time, enzyme variation, and DNA buoyant density. The weight afforded to each of these parameters for specific identification may vary according to the parasite and host studied. Determinations of physiological and behavioral characteristics that are now becoming available should be included in species definitions wherever possible.     

Eimeria of cattle in the Republic of Dagestan

Data on Eimeria (Sporozoa: Coccidia) parasitizing cattle in different regions of the Republic of Dagestan are given. Eight species of the genus were found. Eimeria zuernii, E. subspherica, and E. bovis appeared to be the dominate species. Total infestation rate in the republic is 67.7%, while in mountain regions of Dagestan in is 83%.     

A genetic linkage map for the apicomplexan protozoan parasite Eimeria maxima and comparison with Eimeria tenella

Eimeria maxima is one of the seven Eimeria spp. that infect the chicken and cause the disease coccidiosis. The well characterised immunogenicity and genetic diversity associated with E. maxima promote its use in genetics-led studies on avian coccidiosis. The development of a genetic map for E. maxima, presented here based upon 647 amplified fragment length polymorphism markers typed from 22 clonal hybrid lines and assembled into 13 major linkage groups, is a major new resource for work with this parasite. Comparison with genetic maps produced for other coccidial parasites indicates relatively high levels of genetic recombination. Conversion of ∼14% of the markers representing the major linkage groups to sequence characterised amplified region markers can provide a scaffold for the assembly of future genomic sequences as well as providing a foundation for more detailed genetic maps. Comparison with the Eimeria tenella genetic map produced 10 years ago has revealed a less biased marker distribution, with no more than nine markers mapped within any unresolved heritable unit. Nonetheless, preliminary bioinformatic characterisation of the three largest publicly available genomic E. maxima sequences suggest that the feature-poor/feature-rich structure which has previously been found to define the first sequenced E. tenella chromosome also defines the E. maxima genome. The significance of such a segmented genome and the apparent potential for variation in genetic recombination will be relevant to haplotype stability and the longevity of future anticoccidial strategies based upon multiple loci targeted by novel chemotherapeutic drugs or recombinant subunit vaccines.     

Excystation of the Poultry Coccidium, Eimeria acervulina

SYNOPSIS. Using intervals up to 5 hours, attempts to excyst sporozoites of Eimeria acervulina from intact oocysts in vitro were unsuccessful.
Examination of crop, gizzard, and intestinal contents of chicks fed large numbers of sporulated oocysts indicated that (1) no obvious change in the oocysts occurred in the crop, (2) a high percentage of the sporocysts were quickly released from the oocysts in the gizzard, (3) the sporozoites escaped from the liberated sporocysts in the duodenum and jejunum, and (4) the action of the digestive juice was apparently on the sporocysts rather than on the oocysts.
In vitro attempts to excyst sporozoites from free sporocysts with various pancreatic preparations in the absence of bile produced low or insignificant percentages of excystation. In the presence of bile, bile salts, and other surface-active agents, the action of the pancreatic preparations was greatly increased. The heaviest suspension of motile, nonaggregating sporozoites was obtained with 0.25% trypsin 1–300 in 5% chicken bile at pH 7.6.