Newcastle disease is an OIE-listed and highly contagious viral avian disease inflicting great economic losses and constituting a serious threat to poultry farms all over the world. The paper provides monitoring research results for Newcastle disease among poultry and wild birds in the Russian Federation for 2017. The tests were carried out with diagnostic kits for Newcastle disease virus antibody detection by immunosorbent assay and HI at the FGBI “ARRIAH” Reference Laboratory for Viral Avian Diseases (Vladimir). Biological material delivered from Rosselkhoznadzor Territorial Administrations was collected from 31 678 domestic and 433 wild and synanthropic birds from 22 and 4 regions of the Russian Federation, respectively. The paper shows different levels of seroprevalence in poultry from industrial poultry establishments of a closed type and backyards and in wild birds of various regions of the Russian Federation. Almost total Newcastle disease seroprevalence was found in adult poultry from industrial closed establishments due to a total vaccination against the disease. Broilers demonstrated a relatively low average Newcastle disease virus seroprevalence because of an insufficient antibody level by the moment of blood sampling (mostly during slaughter). On average, antibodies to Newcastle disease virus were detected in one third of samples from backyard poultry. With that, high seroprevalence was registered on farms of North Caucasian Republics and southern regions of the Russian Federation. Seroprevalence in wild birds was moderate. Thus, the monitoring research indicates an unstable epidemiological situation for Newcastle disease in the Russian Federation and the remaining risk of disease outbreak on industrial and backyard farms.
The paper presents data on the study of genetic characteristics of the infl uenza virus A/chicken/ Chelyabinsk/30/2019 H9N2 isolated from pathological material (chicken internal organs) in February 2019 and received from the poultry farm in the Chelyabinsk Oblast. The H9N2 subtype of the isolated virus was identifi ed based on virological analysis. Sequencing of the hemagglutinin gene segment revealed that the amino acid sequence at the cleavage site was RSSR/GLF, which is characteristic of a low virulent avian infl uenza virus. Phylogenetic analysis of the obtained nucleotide sequences of the hemagglutinin gene fragment (1–1539 bp open reading frame) showed that the A/chicken/Chelyabinsk/30/2019 H9N2 isolate belongs to the G1 genetic group of the low virulent infl uenza virus A/H9, the representatives of which are widely spread in the Middle Eastern and Central Asian countries. The complete nucleotide genome sequence of the studied pathogen was determined. The comparative analysis of all genomic segments using the GenBank database revealed a close relationship (over 99%) between the A/chicken/Chelyabinsk/30/2019 H9N2 virus and the A/H9 infl uenza virus isolates circulating in Israel in 2006–2012. According to the analysis of the predicted amino acid sequence of the studied isolate, the positions of some molecular markers that determine the biological properties of the virus have been identifi ed. Most amino acid positions of hemagglutinin (according to H3 subtype sequence numbering) suggest affi nity for the ACA2-3Gal-receptors of avian epithelial cells. Amino acid substitutions were detected at the site within the receptor-binding domain as compared to the A/H9N2 infl uenza virus isolates obtained in Russia in 2018. The primary structure of the A/chicken/Chelyabinsk/30/2019 H9N2 isolate demonstrates a very high level of genetic similarity to the infl uenza virus isolate A/chicken/ Israel/215/2007 H9N2 used as a vaccine strain.
The data on experimental infection of 6-week-old Big-6 cross turkeys with an epidemic A/duck/Altai/469/14 H5N1 clade 2.3.2.1c strain of avian influenza virus are presented. The characteristics of the infection process in birds inoculated intranasally at a dose of 5.0 lg EID50/0.5 cm3 are described with an indication of the incubation period and the mean time of death. The pathomorphological changes at the tissue and cellular level are shown based on histological and immunohistochemical studies of fragments of respiratory, digestive, cardiovascular, nervous, excretory, lymphoid and muscular systems of experimental birds. The testing was carried out using paired preparations of paraffin-embedded tissue sections from experimentally infected and healthy turkeys. One sample was subjected to histological staining using hematoxylin and eosin dyes, and its duplicate was subjected to immunohistochemical assay using a preparation of polyclonal antibodies as primary antibodies against the ribonucleoprotein of avian influenza virus. The results of histological and immunohistochemical studies are photodocumented and presented in the paper. Inflammatory and necrotic lesions of varying severity are detected in the preparations of the trachea, lung, muscular stomach, glandular stomach, small intestine, large intestine, pancreas, brain, cerebellum, heart, kidneys, liver and spleen of turkeys. Immunohistochemical analysis showed the greatest distribution of the influenza virus antigen in the cerebral endothelium, cerebellar Purkinje neurons, acinar cells of the pancreas and in myocardiocytes of the heart. In the course of the experiment it was established that A/duck/Altai/469/14 H5N1 caused a generalized form of infection in turkeys with clinical and pathologic lesions characteristic of highly pathogenic avian influenza.
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