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Title: ANTIBODIES TO EIMERIA MAXIMA GAMETOCYTE ANTIGENS CROSS-REACT WITH EIMERIA TENELLA AND E. ACERVULINA: IMPLICATIONS FOR VACCINE DEVELOPMENT

Author
item BELLI, SABINA - UNIV TECH. SYDNEY, AU
item FERGUSON, DAVID - UNIV OXFORD OXFORD, UK
item SLAPETOVA, IVETA - UNIV TECH. SYDNEY, AU
item KATRIB, MARILYN - UNIV TECH. SYDNEY, AU
item SLAPETA, JAN - UNIV TECH. SYDNEY, AU
item FLOWERS, SARAH - UNIV TECH. SYDNEY, AU
item Miska, Kate
item TOMLEY, FIONA - INST ANIMAL HEALTH, UK
item SHIRLEY, MARTIN - INST ANIMAL HEALTH, UK
item WALLACH, MICHAEL - UNIV TECH. SYDNEY, AU
item SMITH, NICHOLAS - UNIV TECH. SYDNEY, AU

Submitted to: International Journal for Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2009
Publication Date: 5/25/2009
Citation: Belli, S.I., Ferguson, D.J., Slapetova, I., Katrib, M., Slapeta, J., Flowers, S.A., Miska, K.B., Tomley, F., Shirley, M.W., Wallach, M.G., Smith, N.C. 2009. Conservation of proteins involved in oocyst wall formation in Eimeria maxima, Eimeria tenella and Eimeria acervulinaAntibodies to Eimeria maxima gametocyte antigens cross-react with Eimeria tenella and E. acervulina: Implications for vaccine development. International Journal for Parasitology. 39:1063-1070.

Interpretive Summary: The CoxAbic vaccine against coccidiosis in chickens uses a novel approach in inducing immunity against Eimeria infection. The vaccine contains proteins present in Eimeria maxima gametocytes (the sexual forms of the parasite) which are used in building the cyst wall in the developing oocyst. Laying hens are inoculated with the vaccine, and immunity is passed to the chick via maternal antibody transfer. Because the vaccine only contains gametocyte antigens from a single Eimeria species, it has criticized that it would not protect against infections caused by other species of Eimeria. The present study describes the presence and distribution of gametocyte antigens in two addittional species of Eimeria: E. tenella and E. acervulina. Additionally it is shown that antibodies against E. maxima gametocyte antigens cross-react against those present in E. tenella and E. acervulina. This research provides evidence that the CoxAbic (registered trademark) vaccine should provide protection against other species of Eimeria.

Technical Abstract: It has been shown previously that vaccination with gamete specific molecules in Eimeria maxima offers protection via transfer of maternal antibodies (anti-EmAPGA), not just against infection with E. maxima, but also against E. tenella and E. acervulina. Antibodies to the gamete proteins recognise the wall forming bodies in macrogametocytes and oocyst wall of E. maxima (Ferguson et al., 2003). In the present study, these antibodies were examined for cross-reactivity with E. tenella and E. acervulina using immunofluorescence and immunoelectron microscopy during in vivo development of the parasites and Western blotting of gametocyte and oocyst preparations. In all three species, anti-EmAPGA antibodies reacted with wall forming bodies type 1 (WFB1) and type 2 (WFB2) in the macrogamete and the outer layer of the oocyst wall. Anti-EmGam56 antibodies reacted with WFB2 in all three Eimeria species. This was consistent with staining of various bands by Western blotting in all three species and the identification and sequencing of the homologous genes, EtGam56 and EaGam56. In contrast, while anti-EmGam82 stained the WFB2 in both E. maxima and E. acervulina, it did not stain the E. tenella WFB2, even though a homologue of the EmGam82 gene was identified in E. tenella. Predicted protein sequence alignments of the EmGam56 and EmGam82 homologues reveals that, besides sharing regions of great richness in the amino acid tyrosine, strong homology exists at the amino-termini ends, prior to the tyrosine-rich regions of the proteins. ELISAs using truncated recombinant proteins of EmGam56 confirmed that the epitope(s) are located in this region. This study confirms the similarity between the species with respect to macrogamete development and the oocyst wall formation and shows that antibodies to gametocyte antigens of E. maxima cross-react with homologous proteins in the WFBs and oocyst wall of E. tenella and E. acervulina.