Characterisation of macrophage migration inhibitory factor (MIF) from Eimeria species infectious to chickens

MIF Variation

Macrophage migratory inhibition factor (MIF) is a highly conserved protein. Analogs have now be identified from single celled organisms to humans. MIF was first identified in 1966 for its ability to stop macrophage migration (David JR 1966). MIF is now known to be important in both innate and adaptive immunity. MIF seems to have the diametric ability to both induce and suppress inflammation depending on the level of MIF present. At low levels MIF induces inflammation, at high levels MIF suppress inflammation (Kleemann et al 2000). This second action of MIF may explain why pathogens such as Eimeria spp. carry a chicken specific form of MIF. The highest level of MIF expression in Eimeria spp. was found to be in the merozoites stage of development. It is theorized that this MIF expression allows the protozoan to escape immune detection and cause infection. Although each Eimeria spp. carries a chicken MIF, the Eimeria spp. MIF is quite different not only from the chicken sequence but also each different species of Eimeria has a distinct MIF (Miska et al 2006). Targeting of the Eimeria spp. MIF would then be very difficult.