Characterization of Rongchang piglets after infection with type 2 porcine reproductive and respiratory syndrome virus strains differing in pathogenicity

Wenli Zhang; Wenjie Ma; Yu Pan; Xinrong Wang; Mengjie Wang; He Zhang; Junxin Gao; Hongliang Zhang; Zhijun Tian; Changwen Li; Hongyan Chen; Changyou Xia; Yue Wang

doi:10.3389/fmicb.2023.1283039

Characterization of Rongchang piglets after infection with type 2 porcine reproductive and respiratory syndrome virus strains differing in pathogenicity

Front Microbiol. 2023 Oct 18:14:1283039. doi: 10.3389/fmicb.2023.1283039. eCollection 2023.

Authors

Wenli Zhang¹, Wenjie Ma¹, Yu Pan¹, Xinrong Wang¹, Mengjie Wang¹, He Zhang¹, Junxin Gao¹, Hongliang Zhang¹, Zhijun Tian¹, Changwen Li¹, Hongyan Chen¹, Changyou Xia¹, Yue Wang^{1

2

3}

Affiliations

¹ State Key Laboratory for Animal Disease Control and Prevention, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
² College of Veterinary Medicine, Southwest University, Chongqing, China.
³ National Center of Technology Innovation for Pigs, Chongqing, China.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) affects the production and health of pigs and causes severe economic losses to the swine industry worldwide. Different pig breeds have been reported to have different levels of susceptibility to PRRSV, and different PRRSV strains may also influence the infectivity and pathogenicity of the virus. In this study, the susceptibility of Rongchang pigs (a prominent local pig breed in China) to PRRSV infection was thoroughly investigated. Rongchang piglets were exposed to two PRRSV strains: HuN4 (highly pathogenic PRRSV) and SD53-1603 (moderately virulent NADC30-like PRRSV). We observed that Rongchang pigs infected with HuN4 displayed significant clinical manifestations, including fever, reduced body weight, and interstitial pneumonia lesions. Routine blood tests revealed that HuN4-infected pigs exhibited slightly decreased levels of red blood cells, hemoglobin, reticulocytes, and a notable increase in monocytes than control pigs. Additionally, the Rongchang pigs exhibiting severe clinical signs presented a higher neutrophil-to-lymphocyte ratio and a lower lymphocyte-to-monocyte ratio. In contrast, SD53-1603 infection did not cause considerable harm to Rongchang pigs, only resulting in slightly elevated leukocytes and lymphocytes. Furthermore, these two PRRSV strains elicited divergent cytokine responses, such that SD53-1603 infection induced higher levels of TNF-α and IFN-γ, whereas HuN4 infection upregulated IL-1β. These dissimilarities in clinical symptoms, pathological changes, viremia, cytokine expression, and routine blood indices between HuN4 and SD53-1603 infections are critical in understanding the mechanisms of PRRSV infection and developing rational prevention and control strategies against PRRSV.

Keywords: HuN4; PRRSV; Rongchang pig; SD53-1603; immune responses.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by the National Key Research and Development Program (2022YFF0711200), Pilot Technology Project of National Pig Technology Innovation Center (NCTIP-XD1C09), Special Funds for Basic Scientific Research Operations of Central Public Welfare Scientific Research Institutions (1610302022018), the National Center of Technology Innovation for Pigs (NCTIP-XD/B11), the Fundamental Research Funds for the Central Universities (SWU-KR22036), and the Heilongjiang Provincial Key R&D Program Guidance Project (GZ20210010).