Species Of Chicken Coccidia Research Articles

Host specificity of turkey and chicken Eimeria: Controlled cross-transmission studies and a phylogenetic view

Protozoan parasites of the Eimeria genus have undergone extensive speciation and are now represented by a myriad of species that are specialised to different hosts. These species are highly host-specific and usually parasitise single host species, with only few reported exceptions. Doubts regarding the strict host specificity were frequent in the original literature describing coccidia parasitising domestic turkeys. The availability of pure characterised lines of turkey and chicken Eimeria species along with the recently developed quantitative PCR identification of these species allowed to investigate the issue of host specificity using well-controlled cross-transmission experiments. Seven species of gallinaceous birds (Gallus gallus, Meleagris gallopavo, Alectoris rufa, Perdix perdix, Phasianus colchicus, Numida meleagris and Colinus virginianus) were inoculated with six species and strains of turkey Eimeria and six species of chicken coccidia and production of oocysts was monitored. Turkey Eimeria species E. dispersa, E. innocua and E. meleagridis could complete their development in the hosts from different genera or even different families. Comparison of phylogenetic positions of these Eimeria species according to 18S rDNA and COI showed that the phylogeny cannot explain the observed patterns of host specificity. These findings suggest that the adaptation of Eimeria parasites to foreign hosts is possible and might play a significant role in the evolution and diversification of this genus.

Transgenic Eimeria tenella Expressing Enhanced Yellow Fluorescent Protein Targeted to Different Cellular Compartments Stimulated Dichotomic Immune Responses in Chickens

Eimeria tenella, one of the seven species of chicken coccidia, elicits protective immunity against challenge infection with both homologous and heterologous strains. We endeavor to use recombinant E. tenella as a vaccine vehicle for expressing and delivering pathogen Ags and investigate immune responses against these foreign Ags. In this study, two lines of transgenic E. tenella expressing a model Ag, enhanced yellow fluorescent protein (EYFP), targeted to the micronemes and to the cytoplasm of the recombinant parasites were constructed to study the impact of Ag compartmentalization on immunogenicity. The MTT assay, intracellular cytokine staining, and real-time PCR were performed to detect the EYFP-specific proliferation and effector functions of splenic lymphocytes of immunized chickens. ELISA was used to measure anti-EYFP IgG and IgA responses. The results showed that both lines of transgenic parasites stimulated EYFP-specific lymphocyte proliferation and IFN-γ expression in CD4 and CD8 T cells, whereas a higher level of Ag-specific lymphocyte proliferation was elicited by the transgenic line expressing microneme-targeted EYFP. Furthermore, this line stimulated stronger IgA response than the one expressing cytoplasm-targeted EYFP after the second immunization. Our findings are encouraging for further investigation of the effect of Ag compartmentalization in transgenic Eimeria on immunogenicity and for the development of a eukaryotic vaccine vector using genetically modified Apicomplexa parasites.

Antigenic Variation among Strains of Eimeria maxima and E. tenella of the Chicken

The immunogenicity and cross-protection of Eimeria maxima or E. tenella in chickens against their homologous and heterologous strains were evaluated in two experiments. The immunizing strain of E. tenella protected against itself and partially against heterologous strains. The North Carolina (NC) strains of E. tenella were more virulent than the Delmarva (DMV) strains. Growth of the unimmunized groups was depressed 66% and 32% for the NC and DMV strains, respectively. Growth of the immunized-challenged groups (DMV and NC) was depressed by 13%. The DMV E. maxima strains were more virulent than the NC strains. Growth of the unimmunized challenged groups was depressed by 47% (DMV) and 13% (NC). Results demonstrated that there are antigenic variations among strains of two species of chicken coccidia.

Eimeria spp. of the domestic fowl: Resolution of chromosomes by field inversion gel electrophoresis

The molecular karyotypes of five species of chicken coccidia, viz., Eimeria acervulina, E. brunetti, E. maxima, E. necatrix, and E. tenella, were determined using field inversion gel electrophoresis (FIGE). Each species has a distinctive set of resolvable chromosomes which range from about 1 to greater than 5.7 megabases. We were able to resolve at least 8 chromosomes for E. acervulina, 5 for E. brunetti, 10 for E. maxima, 6 for E. necatrix, and 9 for E. tenella. If the value of 67 megabases for the genomic DNA of E. tenella is accurate, then under the conditions used here only about 60% of its chromosomal complement has been resolved.

Field Experience Trials Comparing Narasin and Monensin

Narasin is effective against all species of chicken coccidia when tested in battery cage and floor pen studies. To confirm the efficacy of narasin under practical broiler production conditions, the drug was fed at concentrations of 60 ppm or 80 ppm to broiler chickens being raised by six different commercial broiler producers in five different geographic areas. Monensin was fed in each trial at a concentration of 100 ppm or 121 ppm as a reference control. The usual management practices of each of the integrated broiler companies were followed throughout the respective trials. Nine trials were conducted and approximately 100,000 broilers were tested for each treatment.No adverse reactions attributable to treatments were observed in any of the trials, and performance results obtained with narasin-medicated birds were generally comparable with those obtained with monensin-medicated birds in the same trial. These findings support the conclusion that narasin at final feed concentrations in the range of 60 to 80 ppm can be safely and effectively used as an anticoccidial agent in commercial broiler production facilities.

Chicken Coccidiosis: Correlation Between Resistance and Delayed Hypersensitivity

Broiler chickens were immunized with viable oocysts of Eimeria necatrix, E. tenella, or with a commercially prepared vaccine (CocciVac®D) containing oocysts from eight chicken Eimeria species. Before challenge with oocysts of E. necatrix or E. tenella, delayed hypersensitivity (DH) reactions to particulate-oocyst antigen extracts of E. nectrix, E. maxima, and E. tenella were demonstrated in the previously immunized broilers. Broilers immunized, tested for DH, and challenged showed good correlation between DH reactions and resistance in each homologous trial. Birds immunized with CocciVac®D also gave good correlation between DH reactions to E. maxima, E. necatrix, or E. tenella antigens and resistance when challenged with E. necatrix or E. tenella oocysts. Oocyst antigens from E. maxima, E. necatrix, or E. tenella were cross reactive for DH, indicating some antigen sharing among species of chicken coccidia. A few broilers immunized with chicken coccidia showed DH to an oocyst antigen from E. bovis, a cattle pathogen. Results show that DH to oocyst antigens can predict resistance to coccidiosis.

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.

Comparative Studies with Anticoccidials and Three Species of Chicken Coccidia In vivo and In vitro

At practicable use levels in chickens, some coccidiostats exhibit activity against but 1 or a few species of coccidia, while others have wide-spectrum activity. This might be due to a true variation in species response, or might be a reflection of differences in metabolism and distribution of different drugs in the various sites parasitized by the several species of coccidia. Activities of a number of drugs against Eimeria brunetti, E. necatrix, and E. tenella have been compared both in the chick and in tissue culture. These studies indicate a true species variation in sensitivity to a number of growth factor antagonists, and in the cases of zoalene and methyl benzoquate, possible modifications in activity by drug metabolism and/or distribution. Anticoccidials of the 1940's and 1950's were restricted in the spectrum of their activity at economically and toxicologically usable levels. Thus the sulphonamides showed considerably more activity against intestinal species of coccidia than against Eimeria tenella, while others such as dinitrobenzamide and amprolium were more active against E. tenella than against intestinal species. Wide-spectrum activity was achieved initially by using mixtures of drugs (e.g., Unistat, Pancoxin, Darvisul, Whitsyn). Subsequently, with the discovery of the quinolone, pyridone, and guanidine coccidiostats (e.g., methyl benzoquate, meticlorpindol, robenidine), wide-spectrum control at practical levels could be achieved with a single compound. The differing responses of the various species to different drugs in the chicken gut might be due to genuine species differences in susceptibility, but it could well be merely a reflection of drug absorption, metabolism, and distribution interacting with the differing locations of the various species in the gut. The development of tissue culture techniques for the in vitro cultivation of several species of coccidia has enabled us to compare the anticoccidial activities of a number of drugs against E. tenella, E. necatrix, and E. brunetti without the complicating variables of drug absorption and metabolism and parasite location.

Survival and Development of Five Species of Chicken Coccidia in Primary Chicken Kidney Cell Cultures

Survival and Development of Five Species of Chicken Coccidia in Primary Chicken Kidney Cell Cultures

Poultry anticoccidial agents: Survey of parameters for evaluation

Responses were summarized to a questionnaire on the utility of twelve parameters for anticoccidial evaluation in poultry. Five parameters were very highly acceptable in the three following customary types of trial. In laboratory battery trials these were poultry body weight gains host mortality, efficacy against diverse Eimeria species and strains, and host gross pathology; in floor-pen trials: poultry feed conversion, body weight gains, and host mortality; in field trials: feed conversion and body weight gains. Other parameters with high acceptance in some of the trial types were noninterference with acquired immunity in replacement flocks, poultry production costs, and suppression of Eimeria oocyst production. Most respondents desired data on six species of chicken coccidia (range three to nine) in laboratory trials and floor-pen trials, but not in field trials. There was great divergence on the utility of other parameters.

Response of the Fowl (Gallus domesticus) to Parenteral Administration of Seven Coccidial Species

Live sporozoites or sporulated viable oocysts of Eimeria tenella caused infection after intravenous, intraperitoneal, intramuscular, subcutaneous, or oral inoculations into susceptible chickens. From 0.5 to 2 hr following intravenous inoculation of oocysts, intact and ruptured oocysts and liberated sporocysts were recovered from the lungs. Similar stages were found in the muscles at the inoculation site following intramuscular inoculation. The oocysts recovered from the muscular or subcutaneous site 7 days after inoculation were dead and could not infect other susceptible birds. The seven species Eimeria tenella, E. necatrix, E. maxima, E. acervulina, E. praecox, E. brunetti, and E. mivati Edgar and Seibold, 1964, are tissue specific and become established in the normal area of the digestive tract usually parasitized by these species following subcutaneous inoculation. In all such parenterally induced infections the infection was mild and showed the same incubation period as after oral inoculation. Inoculation of large numbers of cleaned oocysts in a nontoxic medium was required to produce parenterally induced infections. The oocysts developed by parenterally induced infections were normal and viable. Six trials made using parenteral methods of immunization showed insufficient immunity for field operations. Single, heavy, subcutaneous dosages invariably produced mild infection and some immunity, but protection was stronger following single, nonlethal, oral dosages. Intravenous, intraperitoneal, and intramuscular inoculations of rats with oocysts of Eimeria nieschulzi resulted in normal light infections within the digestive tract of the rat (Landers, 1960). Oocysts were recovered from these parenterally induced infections 7.5 days later. Observations following a second infection by the same route suggested that the first inoculation had produced some immunity. Similarly, intraperitoneal inoculations with sporulated oocysts of E. bovis caused infection and clinical signs in calves 17 to 18 days after injection (Fitzgerald, 1962). The degree of immunity was reported to be directly related to the severity of clinical signs. Intramuscular inoculations of oocysts produced signs neither of clinical coccidiosis nor immunity. Nothing is known about the response of the fowl and the ability of coccidia to cause infection when the latter are introduced parenterally into the host except for a brief report by Davies and Joyner (1962). With bacterial and viral organisms parenteral introduction of living attenuated or unattenuated organisms may produce earlier effective immunity and less clinical symptoms than the same organisms introduced orally. Possibly the same hostparasite relationship holds true following coccidial infections of the fowl. When fed orally, the coccidia pass through the digestive tract and each species is highly specific as to the area in which it develops. This tissue specificity is so distinctive that the area of the digestive tract parasitized is recognized as one of the species characteristics in diagnostic procedures. A study of parenteral inoculation of seven species of chicken coccidia was undertaken to provide information on the biology of these parasites and to determine whether this technique could be used in field immunization against coccidiosis. A preliminary report was presented by Sharma and Reid (1962). Received for publication 19 March 1963. * Taken from a dissertation submitted to the Graduate Faculty of the University of Georgia in partial fulfillment of the requirements for the degree of Doctor of Philosophy (1962). t Present address: Dept. of Zoology, University of Lucknow, Lucknow, U.P., India.