Acta Veterinaria et Zootechnica Sinica ›› 2023, Vol. 54 ›› Issue (9): 3812-3823.doi: 10.11843/j.issn.0366-6964.2023.09.021

• PREVENTIVE VETERINARY MEDICINE • Previous Articles     Next Articles

Analysis of ORF5 Gene Variation of Porcine Reproductive and Respiratory Syndrome Virus in Local Regions of China from 2021 to 2022

WANG Zhiyuan1,2,3, LIU Boqi4, XU Zhiying1,2, XU Sijia1,2, XING Jiabao1,2, ZHANG Guihong2,3, WANG Heng1,2*, SUN Yankuo1,2,3*   

  1. 1. Key Laboratory of Comprehensive Prevention and Control for Severe Clinical Animal Diseases of Guangdong Province, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China;
    2. Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Maoming 525000, China;
    3. National Engineering Research Center for Breeding Swine Industry, South China Agricultural University, Guangzhou 510642, China;
    4. Guangdong Haid Animal Husbandry and Veterinary Research Institute Co. Ltd, Guangzhou 511400, China
  • Received:2022-10-26 Published:2023-09-22

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Abstract: In order to investigate the prevalence and genetic variation of porcine reproductive and respiratory syndrome virus (PRRSV) in China, our group collected 117 samples of clinically suspected PRRS symptoms from nearly 50 farms in 13 provinces in China from 2021 to 2022, and conducted genetic variation analysis for the ORF5 gene of PRRSV. The PRRSV-positive samples and genotypes were identified by Quantitative Real-time PCR, RT-PCR was applied to amplify PRRSV ORF5 and ORF7 genes, and the positive samples were sequenced and analyzed for phylogenetic analysis and GP5 amino acid mutations. The results showed that a total of 48 PRRSV-2 positive samples were detected (overall positive rate of about 41%). In addition, a total of 38 ORF5 sequences and 10 ORF7 sequences were obtained by sequencing. The nucleotide similarity among all ORF5 sequences ranged from 77.1% to 99.8%, and the nucleotide similarity among ORF7 sequences ranged from 83.3% to 98.7%. Phylogenetic analysis showed that lineage 1 accounted for 60% (29/48, 28 NADC30-like strains and 1 NADC34-like strain), lineage 3 for 25% (12/48), lineage 5.1 for 5% (2/48), and lineage 8.7 for 10% (5/48). Amino acid site analysis of GP5 showed significant amino acid variation in the signal peptide (aa 1-26), neutralizing epitope C (aa 52-61) and potential N-glycosylation sites (aa 32-35, aa 44, aa 51) were three regions with significant amino acid variants. The results of the study showed that several strains of PRRSV were prevalent in China at the same time, and lineage 1 had replaced lineage 8.7 as the main prevalent lineage and was distributed in most provinces in China; Lineage 3 was second only to lineage 1 and was prevalent mainly in the local area of southern China; Lineage 8.7 were detected at a low rate. It is important to note that a NADC34-like strain was detected in Huizhou City, Guangdong Province, indicating that this strain may have become potentially endemic in South China. The epidemic of PRRSV in China has become increasingly complex in recent years, and the widespread prevalence of lineage 1 strains has increased the genetic diversity of PRRSV. The results of this study will provide a reference for the development of PRRSV prevention and control strategies.

Key words: porcine reproductive and respiratory syndrome virus, ORF5, phylogenetic analysis, NADC30, NADC34

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