De novo genome sequencing and comparative stage-specific transcriptomic analysis of Dirofilaria repens

The zoonotic mosquito-borne filarial nematode Dirofilaria repens causes subcutaneous and ocular infections in dogs, cats and humans. D. repens is transmitted by mosquitoes by ingesting microfilariae (mf) from an infected host, which develop in the mosquito to the infectious third stage larvae (L3). The aims of the project were the de novo sequencing and annotation of the D. repens genome and comparative transcriptomic analyses of the developmental stages mf and L3. The 99.59 MB genome was around 17% larger than that of the related species D. immitis and contained 8.9% fewer predicted genes (10,357). A significantly higher number of D. repens proteins as compared to D. immitis mapped to the filarial nematode L. loa, reflecting the similarity in biology of D. repens and L. loa. A total of 876 genes were differentially expressed, of which 591 could be annotated in UniProtKB/Swiss-Prot. In particular, 155 genes with a UniProtKB/Swiss-Prot annotation to C. elegans and filarial nematodes were upregulated in the L3 and 57 in the mf stage, respectively. Fifteen Gene Ontology Biological Processes were significantly enriched for the L3 group and 12 for the mf. These data provide first insight into the differential gene expression profiles of this filarial nematode and can serve for future investigations of metabolic processes and stage-specific diagnostics.