This paper is a review article outlining the present state of research on the avianinfectious bronchitis virus peplomer protein,emphasizing the molecular biology aspect.The different topics described are as follow:1. Morpholog2.Immunology.3.Haemagglutination activity.4. Relationship to virus serotyping.5. Nucleotidecomposition.The aim and obective of this work is to provide new perspectivein genetically-engineered veterinary vaccine and rapid diagnostic techniques.