Development of patent Litomosoides sigmodontis infections in semi-susceptible C57BL/6 mice in the absence of adaptive immune responses

Background: one of the most advantageous research aspects of the murine model of filariasis,litomosoides sigmodontis,is the availability of mouse strains with varying susceptibility to the nematode infection. in c57bl/6 mice,l. sigmodontis worms are largely eliminated in this strain by day 40 post-infection and never produce their offspring,microfilariae (mf). this provides a unique opportunity to decipher potential immune pathways that are required by filariae to achieve a successful infection. in this study we tracked worm development and patency,the production of microfilariae and thus the transmission life-stage,in rag2il-2rγ-/- mice which are deficient in t,b and nk cell populations. findings: although worm burden was comparable between wildtype (wt) and rag2il-2rγ-/- mice on d30,by day 72 post-infection,parasites in rag2il-2rγ-/- mice were still in abundance,freely motile and all mice presented high quantities of mf both at the site of infection,the thoracic cavity (tc),and in peripheral blood. levels of cytokine (il-4,il-6,tnfα) and chemokine (mip-2,rantes,eotaxin) parameters were generally low in the tc of infected rag2il-2rγ-/-mice at both time-points. the frequency of neutrophils however was higher in rag2il-2rγ-/-mice whereas eosinophils and macrophage populations,including alternatively activated macrophages,were elevated in wt controls. conclusion: our data highlight that adaptive immune responses prevent the development of patent l. sigmodontis infections in semi-susceptible c57bl/6 mice and suggest that induction of such responses may offer a strategy to prevent transmission of human filariasis. © 2015 layland et al.