Submitted to: Proceedings of the Royal Society of London: Biological Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/10/2009
Publication Date: 8/5/2009
Citation: Faust, C., Stallknecht, D., Swayne, D.E., Brown, J. 2009. Filter-feeding bivalves can remove avian influenza viruses from water and reduce infectivity. Proceedings of the Royal Society of London: Biological Sciences. 276:3727-3735. Interpretive Summary: Avian influenza (AI) viruses are spread among wild water birds through an indirect fecal-oral route involving fecal-contaminated water. In this study, filter-feeding clams were added to AI virus contaminated water. The clams removed and killed the virus. These results indicate that clams may serve a positive ecological role my removing AI virus from water and thus limiting transmission among wild aquatic birds.
Technical Abstract: Avian influenza (AI) viruses are transmitted within wild aquatic bird populations through an indirect fecal-oral route involving fecal-contaminated water. In this study, the influence of filter-feeding bivalves, Corbicula fluminea, on the infectivity of AI virus in water was examined. A single clam (n=48) was placed into a flask with distilled water inoculated 1:100 with a low pathogenic AI virus (A/Mallard/MN/190/99 (H3N8)). Water samples were collected prior to inoculation and at time points up to 96-hr post- inoculation (PI) for titration in chicken embryo fibroblasts. Viral titers in water with clams were significantly lower at 24- and 48-hr PI compared to viral-infected water without clams (n=10); however, the onset and rate of viral titer reduction varied between individual trials. To determine if AI virus, that was removed from the water by clams, remained infective 18 wood ducks (Aix sponsa) were divided into six test groups and intranasally or orally inoculated with a variety of treatments of clam supernatant, whole clams, and water exposed to A/whooper swan/Mongolia/244/05 (H5N1). None of the wood ducks inoculated with H5N1 HPAI-infected water that was filtered by clams or that were inoculated or fed tissue from these clams exhibited morbidity or mortality. All of the wood ducks exposed to H5N1 HPAI-infected water without clams and the original inoculum died. These results indicate that filter-feeding bivalves can remove and reduce the infectivity of AI viruses in water, and demonstrate the need to examine biotic, in addition to abiotic, environmental factors that can potentially influence AI virus transmission.