Rezeptoraffinität und Wirtsspektrum von AIVs des Subtyps H16

Rezeptoraffinität und Wirtsspektrum von AIVs des Subtyps H16 Research context Interspecies transmission of influenza viruses may require viral adaptation to cellular sialic acid (Sia)-containing receptors in the target tissues of a new host. Some subtypes of avian influenza viruses (AIVs), such as H5, are able to propagate in a wide range of hosts, while other subtypes, such as H16 (and to a lesser extent H13), have only been isolated from a narrow range of gull species. Hosts also have different levels of susceptibility to AIVs. Some species of wild birds, such as ducks, have been infected with nearly every subtype of AIV (except H16), while some species, such as gulls, are considered as exclusive reservoirs of the H16 subtype. The structure of the receptor binding domain of the AIV hemagglutinin protein and the cellular receptors of hosts are probably instrumental in the virus-host attachment and infection process. We hypothesize that: 1) the HA protein of H16 subtype AIVs has a unique 3D structure that restricts the viruses to a limited range of cell receptors, 2) gull species become more infected with H16 (and H13) subtype AIVs due to the presence of specific types of receptors on the surface of their respiratory and intestinal cells (which are different from the common receptors that are abundant in duck species) and 3) H16 subtype AIVs can propagate more efficiently in gull tissues and gull-derived cells than in duck tissues and duck-derived cells. Our approach: 1) At AIV level: We will study a wide range of H16, H13 and H5 AIVs, their hemagglutinin sequences and 3D structures and their affinity to a range of glycans using sialylglycopolymers and glycan microarray chips to correlate virus structural and genetic properties to glycan (indirectly representing receptor) affinity. 2) At cell and tissue level: We will study the distribution of Sia receptors in the intestine/respiratory tissues and cell cultures of duck and gulls using single specific lectins and lectin microarray chips. We will study the expression of the genes of the enzymes that produce Sias in the cells as an indirect indicator of the presence of the receptors. The results will provide a tool to evaluate any bird species as a potential host for H16 AIVs. 3) At AIV-host interaction level: We will study the affinity of FITC-labeled AIVs to tissue sections; and the replication rate of AIVs by cultivating a variety of H16 and H13 viruses in duck-/gull-derived cell lines; and we will perform animal experiments using selected H16 AIVs and bird species. This will enable us to validate the in vitro and in vivo results in a real virus-host replication and interaction study. Level of originality Our study is novel in that it incorporates a range of conventional and modern techniques to address an important yet neglected question about the role of receptors in the susceptibility of wild birds to infection with two groups of AIVs.