In vivo and in vitro knockdown of FREP2 gene expression in the snail Biomphalaria glabrata using RNA interference.

RNA interference (RNAi) is reported here for the first time for Biomphalaria glabrata, the snail intermediate host for the human parasite Schistosoma mansoni. The fibrinogen-related protein 2 (FREP2) gene, normally expressed at increased levels following exposure to digenetic trematode parasites, such as S. mansoni or Echinostoma paraensei, was targeted for knockdown. Double-stranded RNA (dsRNA) corresponding to specific regions of the FREP2 gene was introduced into snails by direct injection into the hemolymph, 2 days prior to exposure to trematodes, or added to co-cultures of B. glabrata embryonic (Bge) cells and E. paraensei sporocysts. After introduction of FREP2 dsRNA, expression levels of FREP2 were significantly reduced, to 20-30% of control values. In addition, we were able to disrupt expression of the house-keeping myoglobin gene, further confirming the feasibility of RNAi for B. glabrata. Cross-reactivity in RNAi has not been observed either among four FREP gene subfamilies or between FREP2 and myoglobin. Establishment of RNAi techniques in B. glabrata provides an important tool for clarifying the function of genes believed to play a role in host-parasite interactions, specifically between B. glabrata and its trematode parasites, including S. mansoni.