Two independent real time PCR assays were designed to detect and quantify T and N1/88 strains of infectious bronchitis virus (IBV) from faeces of experimentally-infected unvaccinated and unvaccinated laying hens. Vaccination VicS-A3-VicS during rearing can reduce the viral load in the faeces of vaccinated and T or N1/88 challenged hens. Both vaccinated and unvaccinated hens can shed T strain of IBV in faeces up to 9 weeks p.i. It is now possible to detect and differentiate N1/88 strain of IBV from vaccine strains. It is also possible to detect and quantify T and N1/88 strain of infectious bronchitis virus directly from faeces.