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Open Access Short report

Identification of nonessential regions of the nsp2 protein of an attenuated vaccine strain (HuN4-F112) of highly pathogenic porcine reproductive and respiratory syndrome virus for replication in marc-145 cell

Yan-Zhao Xu, Yan-Jun Zhou, Shan-Rui Zhang, Wu Tong, Ling Li, Yi-Feng Jiang and Guang-Zhi Tong*

Author Affiliations

Division of Swine Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No.518, Ziyue Road, Minhang District, Shanghai, 200241, China

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Virology Journal 2012, 9:141  doi:10.1186/1743-422X-9-141

Published: 2 August 2012

Abstract

Background

The regions in the middle of nonstructural protein 2 (nsp2) of porcine reproductive and respiratory syndrome virus (PRRSV) have been shown to be nonessential for PRRSV replication, and these nonessential regions are different in various viral strains.

Finding

In this study, the nonessential regions of the nsp2 of an attenuated vaccine strain (HuN4-F112) of highly pathogenic porcine reproductive and respiratory syndrome virus were identified based on an infectious cDNA clone of HuN4-F112. The results demonstrated that the segments of nsp2 [amino acids (aa) 480 to 667] tolerated deletions. Characterization of the mutants demonstrated that those with small deletions did not affect the viral growth on Marc-145 cells, but deletion of these regions led to earlier PRRSV replication increased (before 36 h after infectious in vitro).

Conclusion

The functional roles of nsp2 variable middle region for PRRSV HuN4-F112 replication have been identified. Our results also suggested that none-essential region might be an ideal insertion region to express foreign gene in PRRSV genome.

Keywords:
HuN4-F112; Nsp2; Nonessential region; Deletion mutant