Chemical shift assignments of nsp7α from porcine reproductive and respiratory syndrome virus.

Porcine reproductive and respiratory syndrome virus (PRRSV) is the causative agent of porcine reproductive and respiratory syndrome, a destructive disease of swine. PRRSV has a single strand positive-sense RNA genome which contains at least ten open reading frames, of these, ORF1a and ORF1b encode polyproteins pp1a and pp1ab. Subsequently, pp1a is cleaved into ten nonstructural proteins, including nonstructural protein 7α and 7β (nsp7α and 7β), the internal cleavage products of a conserved nonstructural protein nsp7. Nsp7 plays a role in provoking the humoral immune system into producing anti-nsp7 antibodies which can be highly and persistently expressed in PRRSV-infected swine. However, the functions of nsp7α and 7β remain unknown. Western blot and radioimmunoprecipitation analysis of the two proteins showed that only cleaved nsp7α was detectable and cleaved nsp7β was not detected in the infected cells. Here, we reported the (1)H, (13)C and (15)N resonance assignment of nsp7α from PRRSV as a basis for further structural and functional studies.