Summary

Coccidiosis in poultry frequently occurs as mixed species infections. Molecular technology can now identify the species present in an infection; however, strains cannot currently be diagnosed. Therefore vaccine strains cannot be distinguished from wild strains. This project aims to develop assays to improve control of coccidia in poultry by distinguishing among strains of Eimeria necatrix and E. tenella using genetic markers (microsatellites). Potential microsatellite markers will be mined from the E. tenella genome then screened against strains of E. necatrix. Species-specific primers will be designed so that DNA from strains of E. necatrix and E. tenella can be amplified directly from faecal samples containing mixed species infections. With species-specific primers strain identity can be diagnosed (i.e. known vaccine versus known or unknown wild) directly from infected faecal samples by profiling 10 microsatellite loci per species.

Program

Chicken Meat

Research Organisation

OLD ABN-The State Of Queensland Acting Through The Department of Employment, Economic Development and Innovation

Objective Summary

1. Develop microsatellite markers to distinguish among strains of E. tenella and E. necatrix.

The objective of this project is to improve management of coccidiosis in poultry by identifying new molecular markers to identify and differentiate strains of Eimeria necatrix and E. tenella. To achieve this objective the aim is to identify variable non-coding, highly repetitive, short strings of DNA called microsatellites. These markers will be identified in the E. tenella genome then tested against strains of E. necatrix. With the ability to distinguish among strains of two of the most economically damaging species of Eimeria the Poultry Industry will for the first time, be able to track the occurrence and spread of virulent strains and better monitor control measures.

2. Determine if delayed protection of E. necatrix in Eimeriavax 4M vaccinated birds a result of vaccine failure or species competition.

Time series profiling of vaccinated birds suggests that there may be insufficient protection afforded by the E. necatrix component of the live mixed species vaccine (Eimeriavax 4M; based on results from RIRDC project DAQ-316A). We aim to conduct a field trial challenging naïve birds with E. necatrix alone and with E. necatrix plus the other vaccine species to determine the cause of this delay (or possible failure) in E. necatrix vaccine protection.