Receptor binding domain of infectious bronchitis virus pathogenic M41 strain

Abstract

IBV (Infectious Bronchitis Virus) is a positive, RNA coronavirus which predominantly causes disease in chickens (Gallus gallus) and causes great economical losses. Earlier studies showed that the spike protein is responsible for receptor binding of the virus to host cells. The spike protein is a glycoprotein which consists of several domains: the ectodomain (outside the virus particle) a transmembrane domain (through the lipide layer) and a cytoplasmic domain (within the virus particle). Up till now the S1 part of the ecotodomain, (216 aminoacid residues to the N terminus of IBV), seems to be responsible for binding. S2 is believed to be responsible for fusion of the virus particle with the host cell. In this study, we investigated the domain within S1 of M41 IBV which is responsible for attachment to the respiratory tissues. To do this we will recombine the S1 protein of two strains of IBV, Beaudette (a nonpathogenic laboratory strain) and M41 (a wild type pathogenic strain). We will test the binding capacity of this recombined protein on chicken tissue. In conclusion, based on the result we obtained, our hypothesis: aminoacid residues relied on the S1 domain are important for binding to the respiratory tissue, could not be confirmed completely. Binding of IBV is not completely depending on the presence of one amino acid. It can be said that Beaudette gains partly binding capacity. And amino acid 38 does play an important role in IBV binding. It remains unclear why this recombined protein does bind to chicken CAM tissue but not to chicken trachea tissue.