MATERNAL TRANSFER OF ANTIBODIES INDUCED BY INFECTION WITH EIMERIA-MAXIMA PARTIALLY PROTECTS CHICKENS AGAINST CHALLENGE WITH EIMERIA-TENELLA

Infection of breeding hens with Eimeria maxima induces production of E imeria-specific IgG antibodies which are transferred to hatchlings via the egg yolk and confer a high degree of maternal immunity against ho mologous challenge and partial immunity to infection with another impo rtant species, Eimeria tenella. As an example, in an experiment using hatchlings from eggs collected between days 28 and 39 after infection of the hens with 20 000 sporulated E. maxima oocysts, control chicks ( challenged with 100 sporulated oocysts) excreted 6.8+/-1.2 million (me an +/-S.E., n = 10) or 5.8+/-1.2 million (n = 8) oocysts of E. maxima or E. tenella, respectively, compared to 0.9+/-0.4 million (n = 5) E. marima oocysts or 2.2+/-0.4 million (n = 9) E. tenella oocysts excrete d by hatchlings of infected hens. This represents an 87% reduction in oocyst excretion with regard to E. maxima and a 62% reduction in oocys t excretion with regard to E. tenella in the progeny of the infected h ens. In another experiment, eggs were collected from days 28 to 37 and again from days 114 to 123 after infection of the hens with E. maxima and hatchling oocyst excretion rates were 82% and 62%, respectively, reduced for E. maxima and 43% and 41%, respectively, reduced for E. te nella in the progeny of hens infected with E. maxima compared to the p rogeny of uninfected hens. ELISA and Western blot analyses of maternal ly-derived IgG revealed a high degree of cross-reactivity to antigens of E. maxima and E. tenella. Thus, maternally-derived, IgG-mediated cr oss-resistance to different species of Eimeria occurs in the chicken, most likely as a result of cross-recognition of conserved epitopes or proteins.