S1 gene-based phylogeny of infectious bronchitis virus: An attempt to harmonize virus classification Viviana Valastro a,b,?, Edward C. Holmes c, Paul Brittond, Alice Fusaroa, MarkW. Jackwoode, Giovanni Cattoli a, Isabella Monne a Infectious bronchitis virus (IBV) is the etiological agent of an acute and highly contagious disease that affects chickens of all ages and poses a major economic burden on the poultry industry. The virus exists in a wide range of antigenically and genetically distinct viral types, making the prevention and the control of this important pathogen both complex and challenging