Authors

L Calarco¹; J Barratt¹; J T Ellis¹; 
¹ School of Life Sciences, University of Technology Sydney, Australia

Discussion

Comparative studies have shown extreme differences
in pathogenicity between isolates of the parasite Neospora caninum which causes abortion in cattle. These
observations led to the hypothesis that intrinsic genetic differences may exist
amongst N. caninum isolates that contribute
to phenotypic differences. To investigate this, the present study employed
a pipeline for the identification of single nucleotide polymorphisms (SNPs) in
the N. caninum genome using RNA-seq
data.  RNA-seq data from two
phenotypically different isolates of N.
caninum; NC-Liverpool and NC-Nowra, were analysed using VarScan 2 to
identify genetic differences between the two, using an assembled transcriptome from
NC-Liverpool as a reference. PCR and DNA sequencing of  SNP-containing loci were then used to extend the SNP data to additional N. caninum isolates in order to investigate
patterns of genetic diversity within the species. Variant analysis identified
3130 SNPs of high confidence, and Sanger sequencing of PCR amplicons captured
56 variants, confirming 86% of these as true variants, supporting the accuracy
of the variants called using the pipeline. The multilocus sequence typing results for ten
isolates of N. caninum revealed a population structure reflecting two
main clades that contain geographically dispersed isolates. The link to parasite virulence will be discussed.