Viruses exploit molecules on target membrane as receptors for attachment and entry into the host cells. Thus, receptor expression patterns can define viral tissue tropism and might to some extent predict the susceptibility of a host for a particular virus. Previously, others and we have shown that respiratory pathogens of the genus gammacoronavirus, including chicken infectious bronchitis virus (IBV), require specific α2-3-linked sialylated glycans for attachment and entry. Here, we studied determinants for binding of enterotropic avian gammacoronaviruses, including those of turkey (TCoV-US), guineafowl (GfCoV) and quail (QCoV), which are evolutionary distant from respiratory avian coronaviruses based on ... More
Viruses exploit molecules on target membrane as receptors for attachment and entry into the host cells. Thus, receptor expression patterns can define viral tissue tropism and might to some extent predict the susceptibility of a host for a particular virus. Previously, others and we have shown that respiratory pathogens of the genus gammacoronavirus, including chicken infectious bronchitis virus (IBV), require specific α2-3-linked sialylated glycans for attachment and entry. Here, we studied determinants for binding of enterotropic avian gammacoronaviruses, including those of turkey (TCoV-US), guineafowl (GfCoV) and quail (QCoV), which are evolutionary distant from respiratory avian coronaviruses based on the viral attachment protein spike (S1). We profiled the binding of recombinantly expressed S1 proteins of TCoV, GfCoV and QCoV to tissues of their respective hosts. Protein histochemistry showed that the tissue binding specificity of S1 of turkey, quail, and guineafowl CoVs was limited to intestinal tissues of each particular host, in accordance with the reported pathogenicity of these viruses in vivo. Glycan array analyses revealed that, in contrast to IBV, S1 of enteric gammacoronaviruses recognize a unique set of non-sialylated type 2 poly-N-acetyl lactosamines. Lectin histochemistry as well as tissue binding patterns of TCoV-S1 further indicated that these complex N-glycans are prominently expressed on the intestinal tract of various avian species. In conclusion, our data demonstrates not only that enteric gammacoronaviruses recognize a novel glycan receptor, but also that enterotropism may be correlated with the high specificity of spike proteins for such glycans expressed in the intestines of the avian host.
