Wolbachiafilarial interactions

Abstract

SummaryWolbachia pipientis is a widespread intracellular bacterial symbiont of arthropods and is common in insects. One of their more exotic and unexpected hosts is the filarial nematodes, notable for the parasites responsible for onchocerciasis (river blindness), lymphatic filariasis (elephantiasis) and dirofilariasis (heartworm). Wolbachia are only present in a subgroup of the filarial nematodes and do not extend to other groups of nematodes either parasitic or free-living. In the medically and veterinary important species that host Wolbachia, the symbiont has become an essential partner to key biological processes in the life of the nematode to the point where antibiotic elimination of the bacteria leads to a potent and effective anti-filarial drug treatment. We review the cellular and molecular basis of Wolbachia filarial interactions and highlight the key processes provided by the endosymbiont upon which the nematodes have become entirely dependent. This dependency is primarily restricted to periods of the lifecycle with heavy metabolic demands including growth and development of larval stages and embryogenesis in the adult female. Also, the longevity of filarial parasites is compromised following depletion of the symbiont, which for the first time has delivered a safe and effective treatment to kill adult parasites with antibiotics. Wolbachia and filarial nematodesAll filarial nematodes of medical and veterinary importance rely on Wolbachia symbiosis, with the exception of Loa loa (Taylor et al., 2005a). The species responsible for lymphatic filariasis (Wuchereria bancrofti and Brugia malayi), onchocerciasis (Onchocerca volvulus) and heartworm (Dirofilaria immitis) have been shown to host Wolbachia in all lifecycle stages and geographical isolates and show close co-evolutionary histories with their nematode host consistent with their mutualistic dependency. A recent study of a broader range of filarial nematode groups has shown that the symbiotic relationship is apparently absent from some individuals and species both within the Onchocercidae and in more ancestral groups infecting lizards, amphibians and birds (Ferri et al., 2011). Taken with the recent genomic analysis which highlights different roles for Wolbachia within its symbiosis with filarial nematodes (Darby et al., 2012), this suggests a broader range of symbiotic relationships exists between different Wolbachia clades.

Wolbachiado not live by reproductive manipulation alone: infection polymorphism inDrosophila suzukiiandD. subpulchrella

“…Wolbachia are maternally transmitted, intracellular endosymbionts estimated to occur in nearly half of all insect species (Zug & Hammerstein 2012) and in many other arthropods (Bouchon et al 1998) and filarial nematodes (Taylor et al 2013). Wolbachia belong to the Rickettsiales order of α-Proteobacteria, whose members include the arthropod-vectored pathogens Ehrlichia and Rickettsia (Werren et al 2008).…”

Phylogenomic analyses uncover origin and spread of the Wolbachia pandemic

“…In stark contrast, Wolbachia of supergroups C and D are found exclusively in some filarial nematodes and their long-lasting intimate association has led to various mutual dependencies 6 . Other distinct Wolbachia strain groups are known only from a small number of hosts: supergroup E is found in springtails (Hexapoda, Collembola), supergroup H in termites (Hexapoda, Isoptera) and further, so far unclassified strains were detected in Ctenocephalides felis (Hexapoda, Siphonaptera), Dipetalonema gracile (Nematoda, Filarioidea), Bryobia sp.…”

Effects of intravenous and subcutaneous heartworm homogenate from doxycycline-treated and untreated donor dogs on bronchial reactivity and lung in cats

“…Wolbachia is critical to D. immitis for production of microfilariae and various stages of the larvae associated with high energy requirements and may become a target of novel antibiotics to treat filarial infections (Kramer and Genchi, 2014;Taylor et al, 2013). Although there are immunologic reactions associated with Wolbachia in the D. immitis host, the pathologic effect of Wolbachia byproducts directly on the host is less clearly defined.…”