China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (3): 1169-1176.doi: 10.16431/j.cnki.1671-7236.2023.03.031

• Preventive Veterinary Medicine • Previous Articles     Next Articles

Screening and Biological Characteristics of Broad-spectrum Riemerella anatipestifer Phage

CHENG Longfei1, LIAO Weilian2, CHEN Hongmei1, JIANG Nansong1, FU Qiuling1, WAN Chunhe1, LIU Rongchang1, SHI Shaohua1, HUANG Yu1, FU Guanghua1   

  1. 1. Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agricultural Sciences, Fuzhou 350013, China;
    2. Animal Disease Prevention and Control Center of Jiangle County, Jiangle 353300, China
  • Received:2022-09-23 Online:2023-03-05 Published:2023-03-02

Abstract: 【Objective】 This study was aimed to screen some broad-spectrum Riemerella anatipestifer phages as candidates for therapeutic phage combinations.【Method】 The host range of 35 phages were determined by spot tests with different contents of phages.The methods of transmission electron microscope observation,thermal sensitivity and pH stability evaluation,determination of the best multiplicity of infection (MOI) in the plural,one-step growth curve drawing and sterilization experiment were used to analyze the morphological features and some biological characteristics of phage.【Result】 Phage vB_RanS_202 had the broadest cleavage spectrum among 35 phages,which could cleave 42% (42/100) of Riemerella anatipestifer strains including 6 serotypes of 1,2,6,10,11 and 13.The phage had a hexagonal head with approximately 60 nm in diameter and a long tail with 220 nm in length,which was not heat-resistant.The titer of phage decreased from 1.0×107 PFU/mL to 1.8×105-2.6×105 PFU/mL after 80 min of 50 ℃ water bath or 20 min of 60 ℃.The phage could maintain its activity at pH 5.0 to pH 9.0.Using RAf488 as host bacteria,the optimal MOI of the phage was 0.01.One-step growth curve indicated that the latent period of phage was 60 min,the outbreak period was 75 min,and the outbreak quantity was 150 PFU/cell.The results of bactericidal experiment against RAf488 showed that phage had good germicidal efficacy when MOI was 0.004 to 0.016.【Conclusion】 Phage vB_RanS_202 had a wide lysis spectrum and the ability of bactericidal in liquid.The results of this study provided a reference for the subsequent screening of phage therapeutic strains.

Key words: Riemerella anatipestifer; phage; phagocytosis spectrum; biological characteristics

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