Submitted to: Coccidiosis International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 8, 2005
Publication Date: September 15, 2005
Citation: Miska, K.B., Lillehoj, H.S., Allen, P.C., Fetterer, R.H., Jenkins, M.C. 2005. The macrophage inhibitory factor of eimeria species. Coccidiosis International Conference Proceedings. p. 163.
Development of drug resistance and the paucity of new chemotherapeutic agents has increased the need for new drugs as well as vaccine targets against poultry coccidiosis. One approach used in identifying novel targets is the random screening of transcripts expressed during the invasive stages of the parasite life cycle. While screening a cDNA library derived from merozoites of Eimeria acervulina a single full-length clone was isolated which shared between 35-38% amino acid identity with the Macrophage Inhibitory Factors (MIFs) of vertebrates. To further characterize Eimeria MIF the full-length Eimeria tenella cDNA was also cloned and sequenced. The amino acid identity between the two Eimeria MIFs is 64%. The mRNA expression pattern of Eimeria MIF was determined using quantitative RT-PCR on RNA collected from several stages of the parasite life cycle. MIF expression profiles in both E. acervulina and E. tenella were found to be almost identical, with high levels of transcripts present in merozoites, while developing oocysts and sporozoites expressed only small amounts of MIF mRNA. Using Western analysis, a 12 kDa protein, corresponding to the molecular weight of MIF, was shown to be highly expressed in merozoites, while expression in other stages were significantly lower. It also appears that MIF is secreted by E. acervulina merozoites. The amount of secreted MIF is increases proportionately with the temperature in which merozoites were incubated. Because Eimeria MIF is strongly associated with merozoites its potential as a vaccine candidate should be evaluated in the future