Fitness Cost ofLitomosoides sigmodontisFilarial Infection in Mite Vectors; Implications of Infected Haematophagous Arthropod Excretory Products in Host-Vector Interactions

Abstract

Filariae are a leading cause of infections which are responsible for serious dermatological, ocular, and vascular lesions. Infective third stage larvae (L3) are transmitted through the bite of a haematophagous vector. Litomosoides sigmodontis is a well-established model of filariasis in the mouse, with the vector being the mite Ornithonyssus bacoti. The aim of the study was to analyse the filarial infection in mites to determine the consequences of filarial infection in the blood-feeding and the reproduction of mites as well as in the regulation of vector-induced inflammation in the mouse skin. Firstly, L3 are unevenly distributed throughout the host population and the majority of the population harbours a moderate infection (1 to 6 L3). Filarial infection does not significantly affect the probing delay for blood feeding. The number of released protonymphs is lower in infected mites but is not correlated with the L3 burden. Finally, induced excreted proteins from infected mites but not from uninfected mites stimulate TNF-α and the neutrophil-chemoattractant KC production by antigen-presenting cells (APCs). Altogether, these results describe the modification of the mite behavior under filarial infection and suggest that the immunomodulatory capacity of the mite may be modified by the presence of the parasite, hindering its defensive ability towards the vertebrate host.

Oxfendazole mediates macrofilaricidal efficacy against the filarial nematode Litomosoides sigmodontis in vivo and inhibits Onchocerca spec. motility in vitro

“…At IMMIP, mice and jirds were naturally infected by overnight contact with infected O . bacoti mites [ 30 ].…”

Migratory phase of Litomosoides sigmodontis filarial infective larvae is associated with pathology and transient increase of S100A9 expressing neutrophils in the lung

“…L . sigmodontis was maintained in our laboratory, and infective third-stage larvae (L3) were recovered by dissection of the mite vector Ornithonyssus bacoti as previously described [ 38 – 40 ].…”

“…Mice were inoculated with 40 infective L3 either subcutaneously into the left lumbar area in 200 μl of RPMI 1640 or intravenously into the caudal vein in 50μl of RPMI 1640. For natural infections mites were left in contact with the mice for 12 h [ 40 ]. A group of 100 infected mites from the same batch was dissected under a binocular microscope to evaluate the average number of L3 per mite.…”

Basophils Are Dispensable for the Control of a Filarial Infection

“…During a blood meal by an arthropod vector, saliva compounds are cotransmitted to the host to facilitate feeding (17). It was recently shown that proteins excreted from the L. sigmodontis vector O. bacoti increased the production of the vasoactive cytokine TNF-a by APCs (18). Although it is likely that increased permeability would also promote infection efficacy, our data suggest that this is not an active L3-mediated process but an intrinsic function of the vector itself that is exploited by the helminth parasite.…”