Eitneria tenella: immunological diversity between asexual generations

Abstract

In the development of a normal strain, WIS, of Eimeria tenella there are three generations of schizogony whereas in an attenuated line, WIS-F-96, derived from WIS, the second and third are absent. Chickens immunized by infection with WIS-F-96, however, were highly resistant to oral challenge with sporulated oocysts of WIS, and histological studies indicated that the immune response was directed against the sporozoites from that challenge inoculum. When challenge of the WIS-F-96-primed chickens consisted of second generation merozoites of WIS (inoculated intracaecally), immunity was less pronounced and the histological data indicated that the merozoites proceeded to develop normally in these birds. These indications of immunological diversity between the merozoites of the first and second generations of schizogony of E. tenella WIS correlated with the results of preliminary studies of the antigenic composition of these developmental stages.

Antigenic diversity of the asexual developmental stages of Eimeria tenella

“…Of particular interest is the low level of cross-reactivity between antigens of the sporozoite and the first generation merozoite and between the first and second generation merozoite. This is in agreement with the results of a previous study that showed both poor immunological cross-protection between these stages and also, from blots probed with convalescent chicken sera, that the first and second generations of merozoites were antigenically different (McDonald et al 1988). In a study on fractionation of organelles of Eimeria tenella, we found that the only reduced polypeptide of sporozoites which was strongly recognized by antisera to first generation merozoites was a microneme-associated antigen of around 100 kDa (Kawazoe et al 1992).…”

“…However, although the antigenic composition of sporozoites has been well documented (Wisher 1986, Sutton et al 1989, Gurnett et al 1990 relatively little is known about the antigens which are present in the first asexual generation or the cross-reactivity of these antigens with those of other asexual generations. The results of experiments in which birds were immunized with the precocious WIS-F-96 line and then challenged with either oocysts or second generation merozoites of the normal parent WIS strain, showed that there is only limited cross-protection between asexual stages and, demonstrated moreover, antigenic differences between sporozoites, first and second generation merozoites (McDonald et a/. 1988).…”

Coccidia: A review of recent advances on immunity and vaccine development

“…Antigenic diversity among asexual generation merozoites has been noted in the E. tenella strain WIS and its precocious derivative WIS-F-96 (McDonald et al, 1988). WIS-F-96 lacks the second and third generations of schizogony, but yet is highly immunogenic.…”

Genomics and Its Impact on Parasitology and the Potential for Development of New Parasite Control Methods

“…For example, studies on precocious lines of Eimeria (Shirley and Bedrnik, 1997) demonstrated that lines with abbreviated life cycles could still induce protection (McDonald et al, 1986(McDonald et al, , 1988). An inactivated vaccine (NeoGuard) based on tachyzoites of Neospora caninum was developed to prevent Neospora-associated abortion in cattle, and this was recently released in the United States and New Zealand (Reichel and Ellis, 2002).…”