Characterization of an Infectious Bronchitis Virus Isolated from Commercial Layers Suffering from False Layer Syndrome.

Infectious bronchitis virus (IBV) is a gammacoronavirus that primarily induces an upper respiratory disease in chickens, also affecting the urogenital tract and occasionally leading to a condition called false layer syndrome (FLS), where sexually mature hens ovulate normally but are unable to lay eggs. Here, we describe an outbreak of FLS in Arizona from which an IBV variant that is nearly 90% homologous to DMV/1639 using the Spike subunit 1 gene, named , was isolated and used in challenge experiments. Three-day-old specific-pathogen-free chicks were challenged with AZ/FLS/17 or M41 in high and low doses, and the disease outcomes were compared.