How myxozoa determines the outcome of co-infection in fish

Myxobolus cerebralis and Tetracapsuloides bryosalmonae are widespread myxozoan parasites that infect rainbow trout and are responsible for trout declines in wild populations and hatchery in USA, Canada and Europe. There is little knowledge on the host proteins whose levels are up-or down-regulated during co- infection with Myxobolus cerebralis and Tetracapsuloides bryosalmonae. This project aims at identifying differential protein profiles of rainbow trout infected with M. cerebralis and T. bryosalmonae in the gills as a portal of entry, and posterior kidney and cranial cartilages as target tissues of PKD or WD pathogenesis at different time points and at elucidating the proteomic background for proteins involved in host recognition and invasion of the infective stages of both parasites. Virulence factors of both parasites that are involved in host recognition and invasion of M. cerebralis and T. bryosalmonae will be identified at the post-transcriptional and post-translational level. We shall also explore the differential modulation of host response and analyse the effect of the proteins whose levels differ after single and co-infection with the two myxozoan parasites. After experimental infection of rainbow trout with M. cerebralis and T. bryosalmonae, samples of the gills, posterior kidney and cranial cartilages will be collected at different time points. Proteomic approaches will be used to identify proteins of both parasites and fish tissues that are present at different levels. In addition, the levels of the mRNA encoding the proteins will be measured by q-RT PCR. The biological functions and networks of the proteins will be investigated. This study will give rise to the first proteomic profiles of rainbow trout in response to co-infection with two myxozoan parasites. It will help explain the observed differences in proteins in rainbow trout in response to M. cerebralis and T. bryosalmonae. The dynamic information will help us understand the biological processes and pathways activated by infection, such as signal transduction and proteasome activity. The results will be used to develop markers for the identification of fish disease and to develop novel approaches for disease management.