Nucleocapsid Protein, PRRSV (N protein)

The nucleocapsid (N) protein of Porcine reproductive and respiratory syndrome virus (PRRSV)  is the main component of the viral capsid to encapsulate viral RNA, and it is also a multifunctional protein involved in the regulation of host cell processes. It plays a crucial role in inhibiting host innate immunity during PRRSV infection. The N protein is encoded by ORF7 gene and it contains 123 amino acid. It is the most abundant protein expressed in infected cells, comprising 40% of the proteins in the virion, and is the most immunogenic protein of the virus. Structural analysis shows that, N protein forms a spherical, possibly icosahedral nucleocapsid core of 20–30 nm diameter, which is surrounded by a lipid envelope containing the viral membrane proteins, yielding a relatively smooth spherical virion of about 60 nm diameter.