Avian infectious bronchitis virus (IBV), a coronavirus, causes infectious bronchitis leading to enormous economic loss in the poultry industry worldwide. Houttuynia cordata (Saururaceae) (HC) is a traditional Chinese medicine used in China. In the present study, the effect of HC on cell infection by IBV was determined using plaque assay and reverse transcription-polymerase chain reaction. The inhibitory effect of HC on IBV infection in ovo and in vivo was analysed using specific pathogen free (SPF) chicken embryos and chickens. Moreover, the effect of HC on cell apoptosis induced by IBV was in...