Cellular Aspects of the Resistance of Chickens to Eimeria tenella Infections*

Abstract

SYNOPSIS. Sporozoites of Eimeria tenella were injected into the peritoneal cavity of normal chickens and chickens immunized against E. tenella. In some experiments normal scrum and serum from resistant chickens were injected prior to the injection of sporozoites. After 15 or 30 minute periods of intraperitoneal incubation, exudates were harvested and the occurrence of intracellular sporozoites was determined. Only macrophages and degranulated granulocytes were observed to contain sporozoites. There was no significant difference between the number of macrophages obtained from normal chickens (normal macrophages) which contained sporozoites and the number of macrophages obtained from immune chickens (immune macrophages) which contained sporozoites. Significantly fewer immune macrophages treated with immune serum contained sporozoites than untreated normal or immune cells, normal macrophages treated with either serum, or immune macrophages treated with normal scrum. Sporozoites in untreated normal macrophages did not appear to be harmed by the intracellular environment, based on structural observations. The majority of sporozoites in macrophages from all other groups were difficult to distinguish within the cytoplasm and were visibly distorted. It is hypothesized that the presence of fewer infected macrophages in exudates of immune chickens and serum‐treated normal chickens was caused by an enhanced ability of these cells to destroy the parasite. Similar observations were noted in the case of sporozoites within degranulated granulocytes of experimental groups. The lack of understanding of the degranulation phenomenon makes it difficult to interpret these findings.

Identification and quantification of granulocytes in caecal mucosa and submucosa of chickens experimentally infected with Eimeria tenella and Salmonella enteritidis

“…Hernández et al (1997) demonstrated that in 5-FU-treated, E. tenella-infected broilers, the absence of heterophils results in an increase in oocyst severity of E. tenella-caused lesions. Huff and Clark (1970) observed that Leghorn chicken heterophils are able to phagocytise E. tenella sporozoites. Stabler et al (1994) demonstrated that broiler heterophils could phagocytise and lyse S. enteritidis, even in the absence of opsonins.…”

“…Heterophils then decreased on d 1, 2, and 3 PI. Huff and Clark (1970) showed the presence of heterophils in Leghorn chickens' peritoneal exudate 15 min after intraperitoneal inoculation with E. tenella. Differences in times of appearance of heterophils might be due to the sample analysed and to the coccidial species used.…”

The role of chicken macrophages in the parenteral excystation of Eimeria acervulina

“…It is not known whether dissolution of the stieda body and activation of sporozoites inside the engulfed sporocysts or in the act of being engulfed took place intra-or extracellularly, but the enzymic and phagocytic activities of macrophages (Lupascu, Bona, Nescu, Gheordu, Hristescu & Iancu, 1970;Huff & Clark, 1970) suggest that these events may have occurred as a result of defensive mechanisms that normally take place within a phagocytic cell. In peritoneal macrophages of mice infected with Plasmodium berghei Lupascu et al (1970) observed enhanced activity of acid phosphatase, a-mannosidase, /?-galactosidase and leucyl-aminopeptidase.…”

“…The peak of this phagocytic activity occurred between 12 and 19 days post-inoculation, when three times as many macrophages from infected birds ingested sporocysts as did macrophages from uninfected controls. Huff & Clark (1970) inoculated E. tenella sporozoites into the peritoneal cavities of normal and immunized chickens and found that sporozoites in 'normal macrophages' did not appear to be affected by the intracellular environment while sporozoites in 'immune macrophages' were greatly distorted. They suggested that destruction of sporozoites accounted for the observation that fewer immune macrophages contained sporozoites than did those from susceptible birds.…”

Enhanced Egress of Intracellular Eimeria tenella Sporozoites by Splenic Lymphocytes from Coccidian-Infected Chickens

“…However, antibody-mediated protective immunity has been demonstrated using passively administered hyperimmune, antigen-specific IgY antibodies (18). Additionally, injection of E. tenella sporozoites pretreated with immune serum into the coelomic cavity of chickens significantly reduced the appearance of parasite-containing macrophages compared with administration of untreated coccidia (13). Taken together with the present findings showing that Eimeria-immune IgY enhances egress and that egress decreases upon B cell depletion, these data provide evidence for an important role of antigen-specific antibodies in an immune-mediated pathway involved in parasite egress.…”