Submitted to: Journal of Veterinary Medical Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 20, 2005
Publication Date: May 8, 2005
Citation: Constantinoiu, C.C., Lillehoj, H.S., Matsubayashi, M., Hoshoda, Y., Tani, H., Matsuda, H., Sasai, H., Baba, E. 2005. Characterization of stage-specific and cross-reactive antigens from eimeria acervulina by chicken monoclonal antibodies. Journal of Veterinary Medical Science 66:403-408
Interpretive Summary: Limited progress in understanding parasite proteins hinders our rapid development of novel vaccines against coccidia. Coccidiosis is the most important protozoan disease of poultry due to its significant economic impact on poultry industry. At least, seven species of Eimeria have been recognized which infect chickens and they parasitize specific areas within the digestive tract with different degrees of pathogenicity and immunogenicity. In this research paper, ARS scientists in collaboration with scientists at University of Osaka and University of Hiroshma developed new sets of chicken monoclonal antibodies (mAbs) that detect proteins at the apical complex of sporozoites from chicken Eimeria spp. and showed that these antibodies also react to the merozoites belonging to Eimeria acervulina. Using immuno-fluorescence assay (IFA), these antibodies binding to the antigens common to sporozoites of E. acervulina and E. brunetti and to sporozoites of all chicken Eimeria. These results enhance our understanding of the nature of coccidia antigens which can be used in vaccine. The results of this paper will help poultry industry to design better vaccines for coccidiosis.
In this research paper, the characterization of 5 chicken monoclonal antibodies (mAbs) that were developed against apical complex antigens on the apical tip of sporozoites from chicken Eimeria spp. is realized and the mAbs reactivity to merozoites belonging to Eimeria acervulina is tested. Using immuno-fluorescence assay (IFA), two mAbs were identified which showed binding to the antigens common to sporozoites of E. acervulina and E. brunetti (mAb HE-4) and to sporozoites of all chicken Eimeria species (mAb 8E-1). The mAbs 8E-1 and HE-4 recognized antigens localized on the apical tip of merozoites from all different stages of development that we examined. The target antigens which are recognized by these two mAbs are common antigens of apical complex and probably involved in host-cell recognition and invasion. Another mAb, 8C-3 which identified an antigen shared by sporozoites and sporocysts of E. acervulina reacted very weak and inconstantly with the merozoites whereas the mAbs 5D-22 and 8D-2 that recognized antigens shared by the sporozoites of E. acervulina and E. maxima (mAb 5D-11) and E. acervulina and E. brunetti (mAb 8D-2)did not react with the merozoites from any generation. Differences regarding the method of fixation were noticed: air dried merozoite stained most intensely followed by acetone and methanol fixed parasites and the glutaraldehyde-fixed parasites did not stain at all. Collectively, these results showed that the invasive stages of chicken Eimeria spp. share cross reactive apical complex antigens which are inter-specie and inter-generation-speific that might represent a potential recombinant vaccine.