Newcastle disease virus vectored vaccines as bivalent or antigen delivery vaccines

Choi, Kang-Seuk

NDV is an avian paramyxovirus type 1 virus belonging to the genus Avulavirus within the family Paramyxoviridae [7] . The virus contains a nonsegmented, negative-sense, singlestranded RNA genome of 15,186 to 15, 198 nucleotides in length, which encodes (3´ to 5´) six structural proteins: nucleocapsid (N) protein, phosphor (P) protein, matrix (M) protein, fusion (F) protein, hemagglutinin-neuraminidase (HN) protein, and RNA-dependent RNA polymerase (L) protein [8] . The length of the NDV genome follows the "rule of six, " which allows efficient virus replication because the N protein binds effectively to six nucleotides [9, 10] . Fig. 1 shows a schematic diagram of NDV morphology. The NDV F and HN glycoproteins are the major structural proteins and comprise a bilayer lipid membrane (envelope) that plays an important role in virus attachment, entry, and release. The M protein resides beneath the envelope and is involved in assembly and budding. The N protein binds to the genomic RNA to form the nucleocapsid (NC) core, and the P and L proteins associate with the NC core to form the ribonucleoprotein (RNP) complex, which is essential for virus replication and transcription [9] . Two nonstructural proteins, V and W, can be produced by RNA editing of the P gene: one (V) or two (W) G residues are inserted at a specific location within the mRNA encoding the P gene [9] . The V protein is an interferon (IFN) antagonist [11] .