Veterynarna biotehnologija – Veterinary biotechnology, 2018, 32, 383-390 [in Ukrainian]. https://doi.org/10.31073/vet_biotech32(2)-47
National Scientific Center "Institute of Experimental and Clinical Veterinary Medicine"
State Research Institute of Laboratory Diagnostics and Veterinary and Sanitary Expertise
State Scientific-Control Institute of Biotechnology and Strains of Microorganisms
BIOLOGICAL PROPERTIES OF LOW PATHOGENIC AVIAN INFLUENZA VIRUS H7N3 ISOLATED FROM WILD DUCKS
Introduction. To date, the influenza virus remains an unpredictable infection for animals, birds and humans. The emergence of new strains and variants with new properties and pathogenicity to new hosts requires constant observation and thorough investigation of new viruses. Some highly pathogenic and low pathogenic avian influenza viruses of H5 and H7 subtypes, characterized by high genetic variability, are concern to the national community as they rapidly mutated, capable of overcoming the interspecific barrier and infecting other animals, including humans.
The goal of the work was to study the biological properties of a low-pathogenic avian influenza virus with 7 subtypes of hemagglutinin isolated from wild ducks, to establish the prospects of its further use as a production strain for the production of veterinary immunobiological preparations.
Materials and methods. The study was carried out using the avian influenza virus A/Mallard/AN/23-15-02/2011, isolated from wild ducks. All work with the pathogen was conducted in special conditions, which excluded the pathogen exposure to the environment. The cultivation of the virus, the determination of the biological and lethal activity of the virus (based on Reid and Mench method) was carried out using chicken embryos at the age of 9-11 days in accordance with the recommendations of the International Office of Epizootics (OIE). The hemagglutinum activity of the virus was determined in the hemagglutination inhibition test with a 1% suspension of red blood cells of the rooster according to the generally accepted method recommended by the FEM. The identification of the virus was carried out using the reference serum antibodies to the influenza A virus subtypes H1-H16 and avian paramyxoviruses PMV1-PMB4 and PMV6-PMV9 produced by the OIE/FAO Reference Laboratory for Newcastle disease and Avian Influenza, the Institutto Zooprofillatico delle Venezie (Italy) and the Veterinary Laboratories Agency (UK).
Results of research and discussion. The results of studies of the biological properties of the bird flu virus subtype H7N3, isolated from wild waterfowl wild ducks in 2011, presented in the title. The ability of the virus to produce specific antibodies was established when the inactivated antigen was administered to experimental chickens in a mixture with the adjuvant "Montanide ISA-70" in the ratio 1:1 in titer (4.7±1.3) log2. The results of the study of infectious and lethal activity of the indicated antigen are also 7.5 lg ЕІD50/0,2cm3 and 1.5 lg ЕLD 50/0.2cm3. According to the results of the sequencing of the EIPKGR/GLE haemagglutinin cutting site, this isolate is classified as a group of low pathogenic ones. Based on the data obtained, a Declaration patent for this strain was received and it was proposed for further use for vaccine production and diagnostic test kits creation. The further conduct of epizootic surveillance activity of the circulation of the influenza virus among waterfowl and synanthropic birds was substantiated.
Conclusions and prospects for further research. The conducted studies proved the belonging of the influenza virus to low-pathogenic variants and the possibility of its use as a component of diagnostic test kits has been proved.
Keywords: low pathogenic avian influenza, wild birds, epizootologic monitoring.