title: Supergroup C Wolbachia, mutualist symbionts of filarial nematodes, have a distinct genome structure.
abstract: Wolbachia pipientis is possibly the most widespread endosymbiont of arthropods and nematodes. While all Wolbachia strains have historically been defined as a single species, 16 monophyletic clusters of diversity (called supergroups) have been described. Different supergroups have distinct host ranges and symbiotic relationships, ranging from mutualism to reproductive manipulation. In filarial nematodes, which include parasites responsible for major diseases of humans (such as Onchocerca volvulus, agent of river blindness) and companion animals (Dirofilaria immitis, the dog heartworm), Wolbachia has an obligate mutualist role and is the target of new treatment regimens. Here, we compare the genomes of eight Wolbachia strains, spanning the diversity of the major supergroups (A-F), analysing synteny, transposable element content, GC skew and gene loss or gain. We detected genomic features that differ between Wolbachia supergroups, most notably in the C and D clades from filarial nematodes. In particular, strains from supergroup C (symbionts of O. volvulus and D. immitis) present a pattern of GC skew, conserved synteny and lack of transposable elements, unique in the Wolbachia genus. These features could be the consequence of a distinct symbiotic relationship between C Wolbachia strains and their hosts, highlighting underappreciated differences between the mutualistic supergroups found within filarial nematodes.
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica (DIVET), Università degli Studi di Milano, Milano, Italy Dipartimento di Biologia e Biotecnologie, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Comandatore
authors.affiliation: Université de Poitiers, UMR CNRS 7267 Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, Poitiers, France.
authors.forename: Richard
authors.initials: R
authors.lastname: Cordaux
authors.affiliation: Dipartimento di Scienze Veterinarie e Sanità Pubblica (DIVET), Università degli Studi di Milano, Milano, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Bandi
authors.affiliation: Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, The School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3TF, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Blaxter
authors.affiliation: Institute of Integrative Biology and the Centre for Genomic Research, University of Liverpool, Liverpool L69 7ZB, UK.
authors.forename: Alistair
authors.initials: A
authors.lastname: Darby
authors.affiliation: Institute of Infection and Global Health, University of Liverpool, Liverpool L3 5RF, UK.
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Makepeace
authors.affiliation: Dipartimento di Scienze Agrarie e Ambientali, Università degli Studi di Milano, Milano, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Montagna
authors.affiliation: Dipartimento di Biologia e Biotecnologie, Università degli Studi di Pavia, Pavia, Italy davide.sassera@unipv.it.
authors.forename: Davide
authors.initials: D
authors.lastname: Sassera
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D005370:Filarioidea / Q000382:microbiology*; D023281:Genomics; D013559:Symbiosis; D020577:Wolbachia / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins
keywords: GC skew; Wolbachia; filarial nematodes; genome characteristics