Overview of current advances in the development of subunit and recombinant vaccines against Newcastle disease virus

Newcastle disease virus (NDV) is one of the most important viral pathogens of avian species and the causative agent of atypical fowl plague, a highly contagious and economically important disease characterized by high mortality rates and reduction of egg production. The HN and F proteins are the main targets for immune response to NDV. Vaccination of poultry with live and inactivated NDV vaccines is the most effective method of control and prevention of Newcastle disease, however due to their disadvantages, efforts are being invested into developing subunit vaccines. To this end, the NDV HN and/or F protein have been expressed using different viruses as vectors, but have also been expressed using transgenic plant systems, yeast and lactic acid bacteria in order to produce the NDV subunit vaccine. Many authors have investigated the possibility of preparation of vaccines from purified and biologically active NDV subunits with HN and F glycoproteins, purified from nucleocapsids, viral ribonucleic acid (RNA) and pyrogens. The above mentioned viral glycoproteins with preserved antigenic structure and biological activities can be used as subunit vaccinal antigens due to their immunogenic properties.