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| What is the cause of the flu? The genomic product of the flu virus |
The influenza virus belongs to the Orthomyxoviridae family and is an enveloped RNA virus. Its appearance is spherical with a diameter of 80-100 nm or a filament of thousands of nanometers. The virus consists of the envelope and the nucleocapsid .
The components of the envelope include membrane proteins (M1, M2), bilayer lipid membranes, and glycoprotein protrusions. The glycoprotein neurites contain both hemagglutinin (HA) and neuraminidase (NA), both of which are antigenic and subtype specific. The nucleocapsid is a thin spiral filament, spirally symmetric, 9 to 15 nm in diameter, including nuclear protein (NP), three polymerase proteins (PB-1, PB-2, PA) and viral RNA; the viral genome is single-stranded Negative strand RNA.
Classification and nomenclature of influenza virus According to the different antigenicity of viral nuclear protein (NP) and membrane protein (MP), the influenza virus is divided into three types: A, B, and C; according to the difference of HA and NA antigens, the same type of virus is divided into two types. Several subtypes. Subtype division is based on genetic analysis and agar diffusion double diffusion. The principles of influenza virus nomenclature published by the World Health Organization in 1980 are as follows: type/host/separation site/segregation date/viral strain number (hemagglutinin subtype and neuraminidase subtype). For example, A/equine/Singapore/3/52 (H7/N3), meaning: influenza A virus/host is horse/separated in Singapore/time is March 1952/subtype is H7N3. Up to now, there have been 15 subtypes of hemagglutinin (H1~15), and 9 subtypes (N1~9) of neuraminidase. The main ones related to humans are A1 (H1N1), A. 2 (H2N2), A3 (H3N2) and Type B.
