INFLUENZA D VIRUSES - PATHOGENS FORMING A NEW GENUS IN THE ORTHOMYXOVIRIDAE FAMILY

Abstract

Influenza pathogens belong to the Orthomyxoviridae family and are divided into genera: Influenzavirus A, B, C, D, as well as Quaranjavirus, Thogotovirus, and Isavirus. For the first time, the influenza D virus was isolated from swine nasal swabs in 2011 in the United States, and its widespread distribution among cattle in France, China, Italy, Ireland, Japan, and several African countries, as well as its ability to infect ferrets, guinea pigs, is further shown. Antibodies to influenza D virus are found in the blood serum of horses, sheep, goats, and in people who have been in contact with cattle. The RNA genome of the influenza D virus is represented by seven fragments responsible for the synthesis of nine proteins. The longest three segments encode for polymerases PB2, PB1, and P3; the fourth and fifth segments encode for hemagglutinin-esterase fusion protein – HEF and nucleoprotein – NP, respectively. The sixth fragment is involved in the synthesis of membrane polypeptides DM1 and DM2, which, in accordance, lines the viral membrane from the inside and performs the function of proton channels. The seventh segment encodes the non-structural protein NS1 and the nuclear export protein NEP; NS1 helps to neutralize cellular interferon and NEP mediates the nuclear export of ribonucleoprotein. Three phylogenetic lines of the influenza virus D are described – D/OK, D/660, and D/Japan, which must be taken into account when preparing vaccines. It is concluded that from its epidemiological, pathological and biological characteristics, the potential ability to cause disease in humans and be transmitted from person to person, new, more in-depth studies are required using ecological-virological and molecular genetic methods.