Dual RNAseq analyses at soma and germline levels reveal evolutionary innovations in the elephantiasis-agent Brugia malayi, and adaptation of its Wolbachia endosymbionts

Abstract

Brugia malayi is a human filarial nematode responsible for elephantiasis, a debilitating condition that is part of a broader spectrum of diseases called filariasis, including lymphatic filariasis and river blindness. Almost all filarial nematode species infecting humans live in mutualism with Wolbachia endosymbionts, present in somatic hypodermal tissues but also in the female germline which ensures their vertical transmission to the nematode progeny. These α-proteobacteria potentially provision their host with essential metabolites and protect the parasite against the vertebrate immune response. In the absence of Wolbachia wBm, B. malayi females become sterile, and the filarial nematode lifespan is greatly reduced. In order to better comprehend this symbiosis, we investigated the adaptation of wBm to the host nematode soma and germline, and we characterized these cellular environments to highlight their specificities. Dual RNAseq experiments were performed at the tissue-specific and ovarian developmental stage levels, reaching the resolution of the germline mitotic proliferation and meiotic differentiation stages. We found that most wBm genes, including putative effectors, are not differentially regulated between infected tissues. However, two wBm genes involved in stress responses are upregulated in the hypodermal chords compared to the germline, indicating that this somatic tissue represents a harsh environment to which wBm have adapted. A comparison of the B. malayi and C. elegans germline transcriptomes reveals a poor conservation of genes involved in the production of oocytes, with the filarial germline proliferative zone relying on a majority of genes absent from C. elegans. The first orthology map of the B. malayi genome presented here, together with tissue-specific expression enrichment analyses, indicate that the early steps of oogenesis are a developmental process involving genes specific to filarial nematodes, that likely result from evolutionary innovations supporting the filarial parasitic lifestyle.

Combinations of the azaquinazoline anti-Wolbachia agent, AWZ1066S, with benzimidazole anthelmintics synergise to mediate sub-seven-day sterilising and curative efficacies in experimental models of filariasis

“…Contrasting depletion levels by lowered dose exposures of anti- Wolbachia drugs in different filarial tissues may reflect effect site pharmacokinetics (i.e., local drug penetration or drug detoxification) or that the Wolbachia residing in the reproductive tissues are intrinsically more sensitive to drug activity, potentially via virtue of higher division rate and metabolic activity. Recent dual RNAseq analysis of Wolbachia gene transcription in the hypodermal vs. the ovarian population within B. malayi indicates a relatively harsher environment in the former location, reflected by upregulation of bacterial stress response proteins, which may impinge on endobacterial growth (Chevignon et al, 2021 ).…”

Wbm0076, a candidate effector protein of the Wolbachia endosymbiont of Brugia malayi, disrupts eukaryotic actin dynamics

“…Moreover, it has been found that transcription levels of the w Bm0076 gene are highest in the body wall and ovaries of the adult female B . malayi , suggesting the effector is involved in either w Bm exit from body wall tissues or invasion of ovaries in this maturation step [ 85 ]. B .…”

Toward novel treatment against filariasis: Insight into genome-wide co-evolutionary analysis of filarial nematodes and Wolbachia

“…Finally, much of the literature on filarial nematodes and Wolbachia focuses on the involvement of T4SS, which facilitate the transport of molecules from bacteria to the inside of host cells. In particular, T4SS is a major exchanger of effector proteins and small metabolites such as nucleotides and their precursors, and it is involved in the control of gene expression and germline development in filarial nematodes ( Rancès et al, 2008 ; Slatko et al, 2010 ; Darby et al, 2012 ; Li and Carlow, 2012 ; Carpinone et al, 2018 ; Lindsey, 2020 ; Chevignon et al, 2021 ). Our data identified an ATPase component of the T4SS and also two components of the T1SS, another key bacterial secretion system that translocates proteins across the outer membrane into the extracellular space.…”