Employees of the reference laboratory for avian viral diseases of the Federal State Budgetary Institution “ARRIAH†obtained additional results of the study of the H5N1 avian influenza virus, which was detected in January 2023 in samples of pathological material from birds from private household plots in the Kaliningrad region.
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In the private farm of the Kaliningrad region in early January, a mass death of chickens was registered.
According to the results of an autopsy performed at the Kaliningrad Testing Laboratory of the Federal State Budgetary Institution “ARRIAHâ€, the fallen bird showed signs characteristic of highly pathogenic avian influenza: swelling and cyanosis of the crest, wattles and eyelids; mucous membranes and subcutaneous tissue are edematous, with hemorrhages; hemorrhagic lesions of the mucous membrane of the glandular stomach.
The primary results of laboratory studies were confirmed in the reference laboratory for viral diseases of birds of the Federal State Budgetary Institution "ARRIAH", where the subtype of the detected virus was determined as H5N1.
When conducting a comparative genetic analysis of the nucleotide sequence of the hemagglutinin gene fragment of the detected virus, it was found that it belongs to the Asian genetic line of the highly pathogenic avian influenza virus subtype H5, clade 2.3.4.4, which received epizootic distribution in 2016-2022 in Asia, Europe, Africa and North America.
According to the GenBank international genetic database, the H5N1 subtype viruses from the Republic of Bangladesh, Nigeria, Benin and the H5N8 subtype viruses from Egypt isolated in 2021, as well as the H5N1 subtype viruses isolated in Spain in 2022 (level similarity 100%).
The avian influenza virus isolate from the Kaliningrad region is genetically close to the H5 subtype avian influenza viruses detected in the period from 2020 to 2022 in different regions of the Russian Federation.
The level of similarity (100%) is observed with avian influenza viruses detected in 2022 in Moscow, Ryazan, Belgorod, Samara, Saratov regions and Khabarovsk Territory; in 2020-2022 in the Chelyabinsk and Rostov regions; in 2021 in the Kaliningrad, Tyumen regions, in the republics of Crimea and Dagestan.
The hemagglutinin cleavage site of the identified avian influenza virus has the REKRRKR structure, which allows it to be characterized as potentially highly virulent. ■