Submitted to: Infection and Immunity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/1/2005
Publication Date: 5/1/2005
Citation: Ding, X., Lillehoj, H.S., Quiroz, M.A., Berensee, E., Lillehoj, E.P. 2005. Protective immunity against Eimeria acervulina following in ovo immunization with a recombinant subunit vaccine and cytokine genes. Infection and Immunity.72:6939-6944. Interpretive Summary: Avian coccidiosis is a major parasitic disease of poultry which costs US poultry industry > $ 600 million annual economic loss. Ability to control coccidiosis will reduce significant economic losses due to this infection and will reduce morbidity. In this paper, ARS scientists describe the development of recombinant peptide vaccine which elicits protective immunity against avian coccidiosis and demonstrated the efficacy of this recombinant peptide vaccine which was delivered into 18-day-old embryos using a commercial in ovo injector. This study showed that a 19-kilodalton recombinant protein from Eimeria acervulina effectively immunized chickens and protected against ill effects of infection. Furthermore, these scientists showed a novel way to enhance vaccine-induced protection by combining recombinant peptide vaccine with recombinant chicken cytokines. In this study, they identified the nature of chicken cytokines which have great immunoenhancing potential opening a new way to utilize chicken cytokines in the vaccines against avian coccidiosis. The results of this study will provide ground work for the development of future generation of novel vaccine against avian coccidiosis.
Technical Abstract: A purified recombinant protein from Eimeria acervulina (3-1E) was used to vaccinate chickens in ovo against coccidiosis both alone and in combination with expression plasmids encoding the IL-1, IL-2, IL-6, IL-8, IL-15, IL-16, IL-17, IL-18, or IFN-gamma genes. When used alone, parasite-specific serum antibody titers induced by low doses (< 50 micro g) of 3-1E were highest at 1 week post-hatch while those following higher dose (> 100 micro g) immunizations were greatest at 2 and 3 weeks post-hatch. Simultaneous vaccination of the 3-1E protein with the IL-1, -15, -16, or -17 genes induced higher serum antibody responses compared with 3-1E alone. To evaluate protective intestinal immunity, vaccinated animals were challenged with live E. acervulina oocysts at 14 days post-hatch and fecal oocyst shedding and body weight gain determined as parameters of coccidiosis. Chickens vaccinated with 3-1E protein showed significantly lower oocyst shedding and normal body weight gain compared with non-vaccinated and infected controls. Simultaneous immunization of 3-1E with the IL-2, -15, -17, -18, or IFN-g genes further reduced oocyst shedding compared with that achieved with 3-1E alone. However, 3-1E plus IL-16, IL-18, or IFN-g inhibited body weight gain exhibited by vaccination with 3-1E alone. These results provide the first evidence that in ovo vaccination with the recombinant 3-1E Eimeria protein induced protective intestinal immunity against coccidiosis and this effect was enhanced by co-administration of genes encoding immune-related cytokines.