Authors

Discussion

Little is known about the mechanisms of virulence or pathogenicity amongst Neospora caninum isolates. NC-Liverpool is extremely pathogenic and infection of laboratory mice results in death, whereas NC-Nowra is far less virulent. These observations suggest that there may be intrinsic, genetic differences amongst isolates. Illumina next generation sequencing was used to compare the tachyzoite transcriptomes of NC-Liverpool and NC-Nowra. The existence of differentially expressed genes occurring in tachyzoites was investigated using a variety of different models, including Cufflinks and CuffDiff or HTSeq, in order to determine how the two tachyozite populations differ at the gene, isoform and exon level. The results show as many as 700 genes may be differentially expressed between the two populations of tachyzoites of N. caninum.  Annotation of these genes by gene ontology shows that “ribosome” and “ATP binding” are highly represented terms in the list of differentially expressed genes, suggesting that protein synthesis and kinase activity by a tachyzoite is an important contributor to virulence in N. caninum. The study also highlights the need for improved annotation of parasite genes.