Pathogenic Characterization of European Genotype Porcine Reproductive and Respiratory Syndrome Virus Recently Isolated in Mainland China

Sun Ming, Ma Yongying, Liu Bohua, Lu Huiying, Deng Xiaoyu, Liu Qiaorong, Qiao Mingming, Chen Xi, Yang Xinyan, Chen Xizhao*
Beijing Anheal Laboratories Co., Ltd, Beijing 100094, China

© 2017 Ming et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the No.68 Beiqing Road, Haidian District, Beijing, China; Tel: +86-10-82898320; Fax: +86-10-82898320; E-mail:



Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen in pig that causes tremendous economic loss in the global swine industry. PRRSV is divided into the European and North American genotypes, with virulence ranging from apathogenic-moderately virulent to highly pathogenic. The emergence of new highly virulent type 1 strains and coexistence of the two genotypes complicate the differential diagnosis, disease prevention, and control of PRRSV. Although the emergence of a novel type 1 PRRSV strain in mainland China was first confirmed in 2011, there is no information available concerning the pathogenesis of this strain.


We sought to determine the pathogenesis of a newly emerged Chinese type 1 PRRSV strain HLJB1.


Pigs were infected with HLJB1 and characterized using serological and histopathological tests.


HLJB1 infection induced transient chemosis, reddened conjunctiva, skin cyanosis, mild transient pyrexia, dyspnea, and tachypnea between 7 and 13 days post-infection. Gross pneumonic lesions were characterized by multifocal, tan-mottled areas. Lymph nodes and spleen were enlarged. Characteristic microscopic lesions consisted of pulmonary consolidation and alveolar septal thickening with red blood cell infiltration, depletion of splenic lymphocytes, and hyperplasia and activation of macrophage. No pigs infected with HLJB1 died during the experiment.


Our findings indicate that Chinese type I PRRSV strain HLJB1 caused classic PRRSV-specific lesions. As it caused lower viremia in pigs compared with other classic type 1 isolates, HLJB1 is less virulent than other type I strains.

Keywords: Pathogenicity, Newly emerged Chinese type I PRRSV isolate.