Asymmetric Wolbachia Segregation during Early Brugia malayi Embryogenesis Determines Its Distribution in Adult Host Tissues

Wolbachia are required for filarial nematode survival andfertility and contribute to the immune responses associated with human filarialdiseases. Here we developed whole-mount immunofluorescence techniques tocharacterize Wolbachia somatic and germline transmissionpatterns and tissue distribution in Brugia malayi, a nematoderesponsible for lymphatic filariasis. In the initial embryonic divisions,Wolbachia segregate asymmetrically such that they occupyonly a small subset of cells in the developing embryo, facilitating theirconcentration in the adult hypodermal chords and female germline.Wolbachia are not found in male reproductive tissues andthe absence of Wolbachia from embryonic germline precursors inhalf of the embryos indicates Wolbachia loss from the malegermline may occur in early embryogenesis. Wolbachia rely onfusion of hypodermal cells to populate adult chords. Finally, we detectWolbachia in the secretory canal lumen suggesting livingworms may release bacteria and/or their products into their host.