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.     

Partial protection against Eimeria acervulina and Eimeria tenella induced by synthetic peptide vaccine

Coccidiosis is a major parasitic disease of poultry industry and an ideal vaccine should induce long-lasting cross-species protective immunity. Broiler chickens (Cobb 500) were inoculated with single, double or triple injections of a synthetic peptide (derived from sequences of Eimeria acervulina and Eimeria tenella antigens) homogenized in Freund's complete and incomplete adjuvants. The immune responses to the vaccine were assessed by evaluation of antibody and lymphocyte proliferation responses, and the degree of resistance of vaccinated chickens to challenge with sporulated oocysts of E. acervulina or E. tenella determined by comparison of their oocyst output with those of control chickens. The results indicated that the synthetic peptide vaccine induced a high level of antibody and cellular responses associated with partial cross-species protection against challenge with sporulated oocysts of E. acervulina or E. tenella.     

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.     

Experimental infections of Eimeria alpacae and Eimeria punoensis in llamas (Lama glama).

Four llamas (Lama glama) ranging in age from 1.5 yr to 7 yr each were inoculated orally with 10,000 (n = 2) or 50,000 (n = 2) sporulated oocysts of Eimeria alpacae (25%) and Eimeria punoensis (75%). The prepatent period for E. aplacae was 16-18 days, and it was 10 days for E. punoensis. Patent periods for E. alpacae and E. punoensis were approximately 9 days and 24 days, respectively. Although large numbers of oocysts were present in feces, no clinical sign of coccidiosis was observed. Based on ths experiment, E. alpacae and E. punoensis at the numbers given are not likely pathogenic in healthy llamas older than 1 yr.     

The immunity arising from continuous low-level infection with Eimeria maxima and Eimeria acervulina.

Chicks were given daily inoculations of 1 or 5 oocysts of Eimeria maxima or 5 or 20 oocysts of E. acervulina. The inoculations ceased after 20 days with E. maxima or 25 days with E. acervulina when oocyst production had stopped. The responses to subsequent heavy challenges showed that with both species the immunity arising from the serial inoculations was stronger and/or more enduring than that produced by single inoculations of comparable numbers of oocysts.     

Immunization by Irradiated Eimeria acervulina

SYNOPSIS. In 5 experiments the infectivity and immunogenicity for chickens of sporulated oocysts of Eimeria acervulina that had been previously subjected to different levels of gamma radiation was tested. It was found that the irradiation doses can be divided into three groups: a) High dosage levels of over 16,000 rad impair the reproduction of the parasites so that few or no oocysts are discharged and no immunity is produced. b) Low dosage levels of 7,000 rad and less permit reproduction and development of immunity not perceptibly different from that resulting from unirradiated oocysts. c) An intermediate range of levels with the optimum from 9,100–13,700 rad induces attenuation while at the same time assuring sufficient immunogenic response.
A dose of 100,000 oocysts or more per bird is required to produce immunity. The optimum irradiation dose increases with the immunizing dose. It was concluded that the development of an irradiated vaccine is possible.     

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.     

Eimeria clethrionomysis sp. n., Eimeria gallatii sp. n., Eimeria pileata sp. n. and Eimeria marconii sp. n. from the red-backed vole Clethrionomys gapperi Vigors, from Pennsylvania.

Four new eimerian species are described from red-backed voles, Clethrionomys gapperi in Pennsylvania. Sporulated oocysts of Eimeria clethrionomyis sp. n. are ellipsoidal, 18.8 (16.5-21.5) x 14.9 (14.0-16.5) with elongate, ovoid sporocysts, 10.6 (9.5-12.0) x6.1 (5.5-7.0). The oocyst wall is smooth, with 2 layers, and thins, with terminal cap at one or both ends. Polar granules, dark Stieda body and sporocyst residuum are present. The oocyst residuum is absent. Sporulated oocysts of Eimeria gallatii sp. n. are ellipsoidal, 27.7 (21-32) x 19.3 (17-24) with ovoid sporocysts, 13.5 (12-15) x 8.8 (8-10). The oocyst wall is smooth, 2-layered, with a micropyle and thin wall at the end opposite the micropyle. Polar granules, Stieda body and sporocyst residuum are present. The oocyst residuum is atypical, of cobwebby material. Sporulated oocysts of Eimeria pileata sp. n. are subspherical to spherical, 25.2 (20.5-29.5) x 22.5 (19.5-25.5) with ellipsoidal sporocysts, 13.4(10.5-15.0) x 8.4 (7.5-9.5). The oocyst wall is rough, pitted, striated, 2-layered, with no micropyle. Polar granules, oocyst and sporocyst residuum, Stieda body and stiedal cap are present. Sporulated oocysts of Eimeria marconii sp. n. are ellipsoidal, 13.0 (10.5-15-0) x 10.6 (9.5-12.0) with elongate, ovoid sporocysts, 7.7 (7.0-8.5) x 4.2 (3.0-4.5). The oocyst wall is smooth, single-layered, with no micropyle. Polar granules, dark Stiedal body and sporocyst residuum are present. There is no oocyst residuum.