ORIGINAL RESEARCH article
Front. Vet. Sci.
Sec. Veterinary Infectious Diseases
Volume 12 - 2025 | doi: 10.3389/fvets.2025.1627238
This article is part of the Research TopicHigh-Impact Respiratory RNA Virus Diseases, Volume IIView all 5 articles
A novel L1C.5 RFLP‑1‑4‑4 recombinant porcine reproductive and respiratory syndrome virus between wild-type virus and a modified-live virus vaccine is highly pathogenic to piglets
Provisionally accepted
- 1Southwest Minzu University, Chengdu, China
- 2Sichuan Boce Testing Technology Co., Ltd., Chengdu, China
- 3Sichuan Animal Science Academy, Chengdu, China
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Porcine reproductive and respiratory syndrome (PRRS) is a severe viral disease in pigs caused by porcine reproductive and respiratory syndrome virus (PRRSV). It poses a severe threat to the global swine breeding industry. Recently, the emergence of PRRSV lineage 1C.5 in the United States and China with the RFLP 1-4-4 pattern has raised worldwide attention; however, there are few studies on the genome and pathogenic characteristics of the L1C.5 RFLP 1-4-4 PRRSV in China. In this study, a novel PRRSV-2 variant, designated GX2024, was isolated from a RespPRRS MLV-vaccinated piglet in China using Marc-145 cells and porcine alveolar macrophages (PAMs). The complete viral genome was further determined and analyzed. Phylogenetic analysis of its ORF5 gene showed that GX2024 belonged to PRRSV-2 L1C.5 (RFLP-1-4-4) group, whereas the complete genome sequence clustered into L8E (JXA1-like) group and it contains a discontinuous 131-aa deletion in NSP2 when compared to the NADC30 strain. Notably, recombination analyses indicated that GX2024 is a multiple recombinant virus from two wild-type PRRSVs L1C.5 (NADC30-like) and L8E (JXA1-like), and a RespPRRS MLV vaccine (L5A) strain. We tested its pathogenicity in four-week-old piglets. To tested the pathogenicity of GX2024, nine four-week-old piglets were divided into two groups (GX2024challenge group, n = 5; negative control, n = 4). GX2024 infection caused high fever (40-42℃) and severe hemorrhagic pneumonia with pulmonary edema. The lymph nodes exhibited obvious hemorrhagic spots with lymphadenopathy. Of note, all GX2024-infected piglets died within 14 days with 100% mortality, indicating that GX2024 is a highly pathogenic PRRSV strain. Our study reports the emergence of a novel highly pathogenic L1C.5 RFLP-1-4-4 recombinant strain, which merits special attention in control and vaccine strategies in China.
Keywords: Porcine Reproductive and Respiratory Syndrome Virus, L1C RFLP-1-4-4, Highly pathogenic, recombination, MLV
Received: 12 May 2025; Accepted: 23 Jun 2025.
Copyright: © 2025 Gao, Zhou, Kang, Lu, Feng, Pei, LIU, Zhang and Zhou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Long Zhou, Southwest Minzu University, Chengdu, China
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