Comparison of resistance level and circulating IgG response in chickens experimentally inoculated with a multiple or a single immunizing doses ofEimeria acervulina

Abstract

Two immunizing methods (Trickle or single immunizing doses) against E. acervulina were tested in chickens. The effects of immu nization and challenge upon growth, oocyst output and circula ting antibodies response (IgG) were compared. Neither immuniza tion method produced pathogenic effects, similar numbers of oocysts were produced, and the levels of IgG in serum were similar and low in each case. After the challenge, immunized birds showed a high level of resistance but susceptible controls produced very large number of oocysts and showed a marked reduction in the growth. Birds immunized by a trikle infection produced oocysts on two days only and the total number of oocysts per bird was very low, whereas those immunized by a single infection produced oocysts over a period of nine days and the total number of oocysts was higher. Susceptible and birds immunized by a single inocula tion showed similar IgG concentration and these were statistically higher than birds immunized by a trickle infection. In susceptible birds the kinetic of IgG was delayed about 4 days. On a comparé deux méthodes d'immunisation (dose unique ou multiple) des poulets vis-à-vis d'une infection par E. acervulina, en étudiant leurs effets sur le poids vif, l'excrétion oocystale et le taux d'anticorps circulants (IgG).Aucune des deux méthodes d'immunisation n'a eu d'effet négatif sur le poids des animaux. L'excrétion oocystale et le taux de IgG dans le sérum ont été faibles dans les deux cas.Après la réinfection, les animaux immunisés ont eu une crois sance journalière égale à celle des témoins non immunisés-non infectés et statistiquement supérieure à celle des témoins infectés. Ces derniers ont éliminé un plus grand nombre d'oocystes.Le taux de IgG est le même dans le sérum des témoins infectés et dans celui des poulets immunisés par une dose unique. Il est statistiquement plus faible chez les poulets immunisés par des doses multiples. D'autre part la cinétique des IgG chez les témoins infectés est retardée de 4 jours par rapport aux animaux immunisés.

A simple model for the within-host dynamics of a protozoan parasite

“…In the second type of experiment, a constant oocyst uptake w per time unit was assumed, and the resulting model behaviour was analysed. The results should agree with experiments on chickens that were given small oocyst doses at regular time-intervals (Joyner & Norton 1976;Norton & Joyner 1986;Galmes et al 1991;Parry et al 1992;Stiff & Bafundo 1993;Graat 1996;Graat et al 1997). All data showed that these so-called trickle infections lead to cessation of oocyst excretion, with doses ranging from 1 oocyst per day to 28 000 twice per week.…”

“…The results should agree with experiments on chickens that were immunized with a single dose or with the same amount of oocysts in multiple small doses at regular time-intervals (trickle immunization; Joyner & Norton 1976;Norton & Joyner 1986;Galmes et al 1991;Nakai et al 1992). The experiments showed that trickle immunization reduces oocyst excretion upon a challenge infection much better than single immunization.…”

“…In the third type of experiment, administration of a single oocyst dose w s or 10 consecutive doses w s /10 were compared with respect to the resulting duration of protection against challenge infection. The results should agree with experiments on chickens that were immunized with a single dose or with the same amount of oocysts in multiple small doses at regular time-intervals (trickle immunization; Joyner & Norton 1976;Norton & Joyner 1986;Galmes et al 1991;Nakai et al 1992). The experiments showed that trickle immunization reduces oocyst excretion upon a challenge infection much better than single immunization.…”

Characterization of immune response to Eimeria tenella antigens in a natural immunity model with hosts which differ serologically at the B locus of the major histocompatibility complex

“…Continuous low-level infection with oocysts, termed trickleimmunization, will induce solid protection against clinical coccidiosis (21,22,53). Although some permutations on this general phenomenon have been reported (12,14,35), this natural model has not been studied adequately with the objective of developing a more thorough understanding of the underlying host immune mechanisms associated with protection, particularly in young chickens. Historically, in vitro immune measurement studies using avian Eimeria spp.…”

Vaccines against the avian enteropathogensEimeria,CryptosporidiumandSalmonella

“…The trickle immunization method produces stronger and longer-lasting immunity than a single immunization containing the same number of oocysts. Chickens immunized with live E. acervulina, either by the trickle procedure or in a single dose, demonstrated both resistance to reinfection, as evidenced by reduced fecal oocyst output, and reversal of growth reduction compared with non-immunized controls (Galmes et al, 1991). Prolonged exposure of chickens to E. tenella was shown to induce protective immunity against challenge by the homologous parasite (Nakai et al, 1992).…”