De novo genome assembly, annotation, and characterization of chemosensory genes in the camel ked (Hippobosca camelina)

Background Hippobosca camelina (camel ked) is an obligate hematophagous ectoparasite that infests camels. Hematophagy inflicts painful bites leading to myiasis, anemia and pathogen transmission such as Candidatus Anaplasma camelii . A genome assembly for this biting flies is currently unavailable, limiting understanding of its genetics, particularly the chemosensory system. Results The genome size for Hippobosca camelina female is 135.6 Mb with 17.08 % repeated regions, an N50 of 1.2 Mb , a total of 2,182 contigs, a GC content of 33.5 % and compleasm (Busco) completion rate of 95.38% with the diptera_odb10 lineage (S:95.83%, 3148, D:0.30%, 10, F:0.30%, 10, I:0.00%, 0, M:3.56%, 117, N:3285) and Hippobosca camelina male had a genome size of 133.5 Mb with 15.38% being repeats, an N50 of 419.6 Kb , 2,318 contigs, GC content of 33.5% , and compleasm (Busco) completion rate of 94.70% with diptera_odb10 lineage (S:94.70%, 3111, D:0.49%, 16, F:0.85%, 28, I:0.00%, 0, M:3.96%, 130, N:3285). A total of 14,240 putative genes for H. camelina male and 13,496 putative genes for H. camelina female annotated were identified as orthologous to genes in selected dipterans that included Drosophila melanogaster, Glossina morsitans morsitans, Glossina fuscipes, Glossina brevipalpis and Anopheles gambiae. Chemosensory genes recovered included 4 Chemosensory specific proteins (CSPs), 18 Ionotropic receptors (IRs), 7 Gustatory receptors (GRs), 5 Odorant receptors (ORs), 9 Odorant binding proteins (OBPs) and 1 Sensory Neuron Membrane Protein (SNMP). Conclusion This study generated two genomes for Hippoboscacamelina. Both are smaller in size compared to Melophugus ovinus (1) and Glossina morsitans (2). The Hippobosca genomes have a lower repeat content compared to G. morsitans and M. ovinus, a phenomenon that may explain the reduced genome size. A total of 44 chemosensory genes for H. camelina were annotated. The obligate parasitic lifestyle, limited movement, and narrow host specificity in Hippobosca camelina could be attributed to reduced chemosensory system genes in the six known families of chemosensory genes as reported in this study.