Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2005
Publication Date: N/A
Technical Abstract: Seven species belonging to the genus Eimeria infect the gut epithelium of chickens resulting in coccidiosis. This infection causes significant economic losses to the poultry industry. Due to development of drug resistance and the paucity of new chemotherapeutic agent, there is an increasing need for new drug as well as vaccine targets. One approach for 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 by RT-PCR using as target RNA collected from several stages of the life cycle. MIF expression in both E. acervulina and E. tenella is almost identical with high expression levels in merozoites, while developing oocysts and sporozoites express small amounts of MIF transcripts. Western blots indicate that protein expression correlates with RT-PCR data, indicating that a 12 kDa protein is expressed highly in merozoites, while expression in other stages is significantly lower. Immuno-fluorescence data suggest that MIF localizes to the apical end of E. acervulina sporozoites and merozoites. The data so far gathered indicate that MIF is primarily associated with Eimeria merozoites, which represent the invasive intracellular stage of the life cycle, making it a good candidate as a potential vaccine target.