Virion The outer surface of the particle consists of a lipid envelope from which project prominent glycoprotein spikes of two types, the haemagglutinin, -135A trimer (HA), and neuraminidase, -60A tetramer (NA)
6 Virion • The outer surface of the particle consists of a lipid envelope from which project prominent glycoprotein spikes of two types, the haemagglutinin, ~135Å trimer (HA), and neuraminidase, ~60Å tetramer (NA)
Haemagglutinin (HA) Encoded by rna segment #4 Can agglutinate red blood cells- hence the nomenclature Cleavage by host-cell protease is required(resulting in Hal and HA2) for infection to occur Hemagglutinin glycoprotein is the viral attachment protein and fusion protein, and it elicits neutralizing, protective antibody responses
7 Haemagglutinin (HA) • Encoded by RNA segment #4 • Can agglutinate red blood cells - hence the nomenclature • Cleavage by host-cell protease is required (resulting in HA1 and HA2) for infection to occur • Hemagglutinin glycoprotein is the viral attachment protein and fusion protein , and it elicits neutralizing , protective antibody responses
Neuramindase (NA) Encoded by rNa segment #6 Enzyme that uses neuraminic (sialic) acid as a substrate Important in releasing mature virus from cells
8 Neuraminadase (NA) • Encoded by RNA segment #6 • Enzyme that uses neuraminic (sialic) acid as a substrate • Important in releasing mature virus from cells
ORTHOMYXOVIRUSES HA- hemagglutinin NA- neuraminidase helical nucleocapsid (RNA plus NP protein) lipid bilayer membrane -polymerase complex MI protein type A, B, C: NP, M1 protein sub-types: HA or NA protein
9 ORTHOMYXOVIRUSES M1 protein helical nucleocapsid (RNA plus NP protein) HA - hemagglutinin polymerase complex lipid bilayer membrane NA - neuraminidase type A, B, C : NP, M1 protein sub-types: HA or NA protein
Influenza virus A
10 Influenza virus A