Identification of Wolbachia like endosymbiont DNA in Setaria digitata genome and phylogenetic analysis of filarial nematodes

Abstract

Setaria digitata is a Wolbachia-free filarial parasite that causes cerebrospinal nematodiasis in non-permissive hosts such as goats and sheep, leading to substantial economic losses in animal husbandry. Therefore, there arises a considerable need for the development of new interventions to disease control and eradication of this filarial parasite. Owing to the limited knowledge on S. digitata genome, it's host-parasite relationship and the potential impact of the Wolbachia endosymbiont in filarial nematodes, this research was focused on the generation of the draft genome of S. digitata; identification of Wolbachia like endosymbiont DNA in S. digitata genome; phylogenetic analysis as well as functional annotation and metabolic pathway analysis of the genome. A draft genome of 78.8 Mbp size with a GC% of 31.45% was generated for the S. digitata worms collected from the peritoneal cavity of slaughtered cattle, using NGS Illumina platform. FASTA36 sequence similarity analysis was able to identify homologous sequences of coxA and gatB Wolbachia MLST genes within the S. digitata genome, while phylogenetic analysis using Geneious Prime Software revealed that S. digitata is more closely related to the filarial nematodes with Wolbachia endosymbiont than Wolbachiafree filarial nematodes. Furthermore, BLAST2GO analysis was able to identify 6055 annotations and 95 metabolic pathways within the S. digitata genome. Based on FASTA36 and phylogenetic analyses, it can be concluded that ancestors of S. digitata were colonized with Wolbachia in the distant past, and suspected gene transfer may have brought Wolbachia DNA into the S. digitata nuclear genome prior to endosymbiont loss. Keywords - Setaria digitata, Wolbachia, NGS