Acta Veterinaria et Zootechnica Sinica ›› 2025, Vol. 56 ›› Issue (2): 788-802.doi: 10.11843/j.issn.0366-6964.2025.02.028

• Preventive Veterinary Medicine • Previous Articles     Next Articles

Construction and Identification of Infectious Clone of the Avian Metapneumovirus of Subtype B Strain B1

YU Zekun1,2(), JIANG Chengyuan2, YUAN Hongxing3, ZHOU Sheng2, DUAN Xiaoxiao4, LI Yan4,*(), SONG Qinye1,*()   

  1. 1. College of Veterinary Medicine, Hebei Agricultural University, Baoding 071000, China
    2. Shandong Sinder Technology Co., LTD, Weifang 262200, China
    3. Agriculture and Rural Bureau of Guantao County, Handan City, Hebei province, Guantao 057750, China
    4. Qingdao Animal Disease Prevention and Control Center, Qingdao 266100, China
  • Received:2024-04-07 Online:2025-02-23 Published:2025-02-26
  • Contact: LI Yan, SONG Qinye E-mail:zekun_yu@qq.com;liyanqd2008@163.com;songqinye@126.com

Abstract:

Avian metapneumovirus (aMPV) subtype B is associated with the development of swollen head syndrome in chickens, which can lead to immunosuppression, severe secondary infections, and a subsequent decline in the productive performance of the poultry. The establishment of a reverse genetics system for domestic aMPV isolates is of considerable significance for advancing virological research and facilitating the development of targeted vaccines. The amplicons of the viral genome were sequenced individually, and the complete genome sequence of the aMPV B1 strain was deduced through sequence assembly. The genome was divided into four segments based on enzyme cleavage sites and sequentially inserted into the pTH vector to construct the viral genome plasmid pTH-B1. A synonymous mutation introduced at position 7 474 of the viral genome to silence the Sal I cleavage site as a genetic marker. A Pme I cleavage site was introduced between the M and F genes of the pTH-B1 plasmid, and the EGFP expression cassette was inserted using this site to obtain the plasmid pTH-B1EGFP. The expression cassettes of the viral N, P, and M2.1 genes were co-cloned into the pCI-Neo expression vector, yielding the auxiliary plasmid pCI-NPM2.1. The L gene was individually cloned into the pCI-Neo expression vector, yielding the auxiliary plasmid pCI-L. The pTH-B1 and pTH-B1EGFP plasmids were co-transfected with the two auxiliary plasmids into BSR/T7 cells, respectively. Subsequently, the transfected cells were co-cultured with Vero cells and continuously passaged for further analysis. The successful rescue of the rB1 and rB1-EGFP strains was confirmed through the observation of cytopathic effects (CPE) and green fluorescence, along with the detection of vrial N gene and genetic marker, indirect immunofluorescence assay (IFA) and Western blot. The proliferation levels and trends of the rB1 and rB1-EGFP strains were found to be similar to those of the parental virus strain. This study successfully obtained the infectious clone of the subtype B avian metapneumovirus B1 strain using a three-plasmid rescue system. The intergenic non-coding region between the M and F genes is capable of accommodating gene expression sequences, which lays a necessary foundation for further investigation into the pathogenesis of subtype B aMPV and the development of vaccines.

Key words: avian metapneumovirus subtype B, infectious clone, a three-plasmid rescue system, viral rescue

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