Systematic Veterinary Virology

MORPHOLOGY

• Influenza virus particles are highly pleiomorphic (variable), mostly spherical/ovoid, 80-120 nm diameter, but many forms occur, including long filamentous particles (up to 2000 nm long x 80-120 nm diameter).
• The outer surface of the particle consists of a lipid envelope from which project prominent glycoprotein spikes of two types Haemagglutinin (HA) and Neuraminidase (NA).
• The inner side of the envelope is lined by the matrix protein.
• The genome is packed into the core along with nucleoprotein (NP).
• The genome - RNA and nucleoprotein together are called RNP.
• The genome is of s/s  (-)sense RNA arranged into 8 segments. The segments 1-3 code for various transcription related activities. Segments 4, 5 and 6 code for HA, NP and NA proteins. Segment 7 codes for matrix protein and 8 codes for non-structural proteins.