Developing a DNA hybridization technique for the detection of two pathogenic Eimeria species of chicken

A.K. Adlin Azlina, A.H. Zainal-Abidin, Z. Zulkiflie, M.S. Jangi and F.M. Tomley

Abstract

Poultry coccidiosis is caused by Eimeria spp. of the phylum Apicomplexa. Coccidiosis still continues to be an important threat to poultry industry. Diagnosis based on microscopic technique is usually used to differentiate species, however these techniques are still less efficient, insensitive and less specific for the detection of mix infections in chicken. Therefore, a DNA-based test particularly using ribosomal RNA (rRNA) was chosen to identify a molecular marker to enable a faster and more sensitive identification of a particular species. In this study, the 5S rRNA gene was chosen because of its high degree of conservation, ubiquity and the relative ease with which it can be cloned. It also has a semi-conserved region from which a species-specific primer can be designed. The size of 5S rRNA gene is 120 nucleotides and the spacer is different in size and sequence for each species. From this spacer, primers for each species have been designed. Probes from E. tenella and E. maxima were developed using the specific primers. Using dot-blot, these probes showed that they can be used to differentiate these two species from the others. Probes designed for two of the species i.e. E. tenella and E. maxima were found to be specific in detecting the parasites. This study showed that information related to 5S rRNA genes is useful because it can be used to develop molecular markers for future diagnostic work on parasites.

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