Abstract: Porcine reproductive and respiratory syndrome virus is an enveloped, positive-sense RNA virus, which belongs to the family Arteriviridae, order Nidovirales. Besides the Arteriviridae, Nidovirales always includes the Coronaviruses. The 15.1~15.2 kb PRRSV genome code the proteins through some open reading frames (ORFs), and the ORFs tend to overlap one another. Translation of ORF1a produces pp1a polyprotein, and the formation of pp1ab polyprotein is led by the expression of ORF1b. The pp1a and pp1ab polyproteins release fourteen non-structural proteins after processed by viral proteases. Some of the non-structural proteins are proteases (NSP1, NSP1β, NSP2 and NSP4), RNA-dependent RNA polymerase (NSP9), helicase(NSP10) and endonuclease(NSP11). ORFs2-5, ORF6 and ORF7 encode GP2-5, M and N, respectively. ORF2b is enclosed within ORF2 fully and express small, non-glycosylated E or 2b protein. A portion of envelope protein belongs to nidoviruses particularly, and all the structural proteins is necessary for infection.

Key words: PRRSV; protein; envelope protein