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Since 2010 the year when it was first reported in domestic ducks in China, highly pathogenic avian influenza (HPAI) H5N8 has caused several outbreaks in different countries. The first outbreak wave was documented in South Korea and Japan in 2014 and the second wave was reported in Asian and European countries in 2016. More importantly, zoonotic infection was first reported in poultry workers in Russia in 2021. Therefore, active surveillance on H5N8 is highly needed. Surveillance on live birds instead of environmental samples is commonly reported. In the present study, we reported detection and genomic characterization of an environmental H5N8 strain in environmental samples of Tongzhou poultry meat markets in Beijing on a monthly basis from March 2021 to February 2022. Among 600 samples screened, a total of 27 samples were positive for influenza A virus with 4 typed as H5N8, 10 H7N9, and 13 H9N2. Whole genome sequencing and analysis of one duck neck with a higher virus load showed that A/Environment sample/Beijing/TZ001/20 21 (H5N8) clade 2.3.4.4b had the highest identities (over 99%) in all eight segments with H5N8 isolates from wild birds swan and tern in Hubei and had polybasic cleavage site PLREKRRKR/G, characteristic of a HPAI virus. Overall, our data indicate that HPAI H5N8 virus is still circulating in domestic ducks in China in the study period and continued surveillance in domestic and wild birds is needed to control H5N8. [ABSTRACT FROM AUTHOR]

It is well known that mast cells (MC) are involved in fibrosis and many forms of chronic inflammation. Chronic inflammatory cells infiltration and fibrosis in various orbital tissues are the main histopathologic features in patients with idiopathic orbital inflammatory pseudotumor (IOIP). Whether MC is involved in the course of chronic inflammatory conditions of IOIP is not yet clear. We sought to investigate the distribution of MCs in samples of IOIP and to explore the possible role of MC in the course of its pathegenesis. Immunohistochemistry with tryptase monoclonal antibody (a specific mast-cell surface marker) was used in 53 different subtypes of IOIP specimens including 19 of the lymphocyte infiltrative type, 22 of the fibrotic type, 12 of the mixed type and 4 specimens of normal orbital tissue. The number of positive stained MC was counted by light microscopy. The differences of the number of MC between various subtypes of IOIP were analyzed. The average number of positive stained MC in the normal control group was 33.33 ± 4.72 /mm3, whereas the average numbers of positive stained MC in the lymphocyte infiltrative subtype group, the mixed subtype group and the fibrotic subtype group were 306.35 ± 55.81 /mm3, 662.93 ± 115.28 /mm3 and 813.44 ± 146.56 /mm3, respectively. Compared with the normal control, the number of MC increased significantly in all three subtypes of IOIP samples ( P < 0.01). The number of MC in fibrotic subtype IOIP was the largest, followed by mixed subtype IOIP, and the lymphocyte infiltrative subtype IOIP ( P < 0.05). The MC were distributed mainly around small vessels and in collagen fibers. Mast cells may play an underappreciated role in the fibrosis of IOIP. [ABSTRACT FROM AUTHOR]