Effect of Nonstructural Protein 2 Hypervariable Regions in the Replication of Porcine Reproductive and Respiratory Syndrome Virus in Marc-145 Cells

Publisher: Karger

E-ISSN: 1423-0100|58|5|288-296

ISSN: 0300-5526

Source: Intervirology, Vol.58, Iss.5, 2015-0, pp. : 288-296

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Abstract

Background: Highly pathogenic (HP) porcine reproductive and respiratory syndrome virus (PRRSV) causes prolonged high fever, red discoloration of the body, blue ears and a high mortality. Previously, we found that the PRRSV vaccine strain TJM contained a deletion of 120 amino acids (aa 628-747) in nonstructural protein 2 (Nsp2). We aimed to explore the replication features of PRRSV after adding the transiently expressed product of these 120 aa in vitro. Methods: We constructed seven eukaryotic expression plasmids containing different parts of the 120-aa sequence, transfected them into Marc-145 cells and then inoculated the cells with 103 TCID50 TJM per well. We detected virus replication at mRNA and protein level by real-time RT-PCR and Western blotting, respectively, and determined the virus titer. Results: The transiently expressed 120 aa and one of its truncated polypeptides inhibited PRRSV TJM propagation on Marc-145 cells. The complete 120-aa sequence induced a remarkable decrease in PRRSV replication, causing a reduction in structural protein levels between 36 and 48 h after infection. Additionally, aa 628-727 partly reduced the replication of PRRSV on Marc-145 cells. Conclusions: The 120 aa from Nsp2, especially aa 628-727, play a negative role in PRRSV TJM proliferation.