ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2019, Vol. 50 ›› Issue (4): 802-810.doi: 10.11843/j.issn.0366-6964.2019.04.013

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Phylogenetic Analysis and Pathogenesis in Mice of a Novel Reassortant H1N2 Subtype Swine Influenza Virus

XU Chengzhi1, WU Yunpu1,2, JIA Yunhui1, YANG Shiman1, HE Likun2, CHEN Yan1, ZHOU Chenyang2, YANG Huanliang1, QIAO Chuanling1*, CHEN Hualan1   

  1. 1. State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China;
    2. Liaoning Provincial Center for Animal Disease Control and Prevention, Shenyang 110164, China
  • Received:2018-10-17 Online:2019-04-23 Published:2019-04-23

Abstract:

The objective of this study was to investigate the epidemiological situation of swine influenza and viral molecule characteristics in North-eastern China. One H1N2 subtype swine influenza virus, designated as A/swine/Liaoning/FX575/2016 (H1N2) (FX575), was isolated from a slaughterhouse in Liaoning province during an active surveillance in 2016. The complete genomic sequence of the strain was sequenced and subjected to phylogenetic analysis, molecular characteristic analysis and genotypic analysis. Then, the viral pathogenesis was carried out by intranasal infecting the six-week-old female BALB/c mice and evaluated by measuring body weight loss of mice and virus replication titer. FX575 was a triple reassortant H1N2 virus, which had the nearest genetic relationship with the H1N2 influenza viruses previously isolated from China. Phylogenetic analysis results demonstrated that HA gene of the isolate belonged to the Eurasian avian-like swine H1N1 lineage, the NA gene was clustered into the North American swine H1N2 lineage, and the six internal genes fell into the pandemic 2009/H1N1 virus lineage, respectively. The virus FX575 could cause significant weight losses of mice within one week after infection, and one mouse with its weight loss exceeding 25 percent was considered dead. The viral replications occurred both in lungs and nasal turbinates, with the titers of 4.82 and 4.20 log10EID50·mL-1, respectively. The results indicated that continuous reassortments of different genotypes of influenza viruses occurred in the swine population, and the novel reassortant virus showed moderate pathogenicity to mice, which further suggested that the active monitoring of SIV should be strengthened in the future.

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