Characterization
of cryptic field isolates of Eimeria spp. from chickens.
Wayne G. Woods and D. Grant Richards*
Eimeria Pty Ltd, 250 Princes Highway, Werribee, VIC,
3030. Australia.
*medichick@ava.com.au
The identification
of variants of Eimeria species has important implications
in discovering emerging strains not covered by current
vaccines. It was therefore important, in Australia,
to determine if local strains reflected overseas trends
in this regard.
We have been studying the species composition of coccidiosis
outbreaks in Australian chickens. The technique we
employ involves the isolation of DNA from faecal oocysts
and a PCR/electrophoresis analysis of the ITS-2 region
of the parasite genome. All previously analysed strains,
encompassing the seven known species of chicken Eimeria,
are present species-specific banding patterns, with
only minor variation in band positions between strains.
From the analysis of field samples, we have obtained
isolates that represent two novel banding patterns.
Pure isolates of these two cryptic taxa were obtained
first by passage of mixed-species oocysts through
hyperimmunized birds, and then isolation and amplification
of single oocysts. The isolates were then characterized
by biometrics, macro- and microscopic gut lesions,
prepatent period, reproductive index and genetic sequencing.
This poster details the isolation, characterization,
and taxonomic affiliation of these two taxa.