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2022-12-9 16:35:46

Wan Z, Jiang W, Gong J, Zhao Z, Tang T, Li Y, Zhan. Emergence of Chicken Infection with Novel Reassortant H3N8 Avian Influenza Viruses Genetically Close to Human H3N8 Isolate, China. Emerg Microbes Infect. 2022 Sep 23:1-10
submited by kickingbird at Sep, 24, 2022 21:5 PM from Emerg Microbes Infect. 2022 Sep 23:1-10

Wild aquatic birds are the primary natural reservoir for most subtypes of avian influenza viruses (AIVs) [1]. These viruses often spill over to poultry and some can subsequently be transmitted to humans. In the past two decades, multiple subtypes of IAVs from chickens, including H5N1, H5N6, H7N9, H9N2, H10N3 and H10N8, etc., have caused human infections [2, 3, 4, 5], with high mortality being recorded among the H5N1 and H7N9 cases. Chickens in the interspecies transmission of AIVs highlights the importance of continued surveillance of the emerging AIVs that may pose a risk to public health. Here, we report the isolation and characterization of H3N8 viruses from domestic chickens with respiratory symptom, which are closely related to the index human H3N8 isolate [6].

During the winter season of 2021-2022, a respiratory disease occurred in 30-40 days old domestic chickens from several poultry farms in eastern China. Three H3N8 AIVs were isolated from the tracheal and lung samples from sick chickens, and designated as A/chicken/Anhui/081/2022(H3N8) (AH081), A/chicken/Jiangsu/046 /2022(H3N8) (JS046) and A/chicken/Jiangsu/382/2022(H3N8) (JS382), respectively. To understand the origins of these H3N8 isolates, we sequenced their genomes and performed phylogenetic analysis. Phylogenetic trees were constructed by using the maximum likelihood in software of MAGE X. The HA genes of these viruses were of Eurasian H3 lineage, which has been circulating in ducks since 2008 (Figure 1A). Their NA genes were genetically associated with those from H3N8 circulating in wild birds in North America (Fig. 1B). Both HA and NA genes shared high identity to those from the H3N8 that caused the first case of human infection [7]. The internal genes were genetically close to the G57 genotype H9N2, which has become predominant in chickens since 2010 in China [8]. The internal gene constellation in general is very similar to that of the human H3N8 isolate, especially AH081, sharing 99.5%-100% nucleic acid homology with A/Henan/4-10CNIC/2022(H3N8).

Figure 1. Phylogenetic trees of hemagglutinin (A) and neuraminidase (B) genes of the novel three H3N8 AIVs isolated from chickens in China, 2022. The trees were generated by maximum likelihood with the MAGE X software. The viruses from this study were labeled in black circles, the H3N8 AIVs that caused human infections in China were marked in red. Scale bars indicate branch length based on number of nucleotide substitutions per site. (C) Receptor-binding properties of the H3N8 viruses. The receptor binding of the H3N8 viruses was determined using various concentrations of sialic acid conjugated to biotinylated sialylglycopolymers (3’SLN and 6’SLN) via direct solid-phase binding assays, A/Chicken/Jiangsu/X1/2004(H9N2) (X1) and A/PuertoRico/8/1934(H1N1) (PR8) were selected as α-2,3 receptor and α-2,6 receptor controls, respectively. Growth kinetics of the H3N8 viruses in MDCK and A549 cells. MDCK and A549 cells were infected with each virus at an MOI of 0.001 (D and E). Supernatant samples were collected at 6, 12, 24, 48 and 72 hpi, and viral titers were measured in MDCK and A549 cells, respectively. Pathogenicity of the three H3N8 viruses in mice. Five-week-old BALB/c mice were infected intranasally with 105 TCID50 units of each virus. Percentage of bodyweight change of mice infected with each virus (F). The viral titers of the lungs of the infected mice collected at 3 and 6 dpi were measured in MDCK cells (G).

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