General Properties of Influenza a virus Enveloped virus with helical symmetry SS-RNA (segmented) genome with negative polarity 8 unique segments, 10 protein products All proteins but one(NS1)are structural Host nucleus required for replication Unusual for an rna virus
General Properties of Influenza A Virus – Enveloped virus with helical symmetry Enveloped virus with helical symmetry – ss-RNA (segmented) genome with negative RNA (segmented) genome with negative polarity – 8 unique segments, 10 protein products – All proteins but one (NS1) are structural – Host nucleus required for replication • Unusual for an RNA virus
2. Morphology structure 80-120nm, envelope Spikes: glycoproteins-
2. Morphology & structure • 80 —120nm ，envelope • Spikes: glycoproteins Spikes: glycoproteins--
Virion Structure- Diagram Envelope glycoproteins(spikes) Hemagglutinin (HA Neuraminidase (NA) Negative sense SSRNA MI: matrix M2. ion channel IIPS M1 NP: nucleoprotein NA helical nucleocapsid B2 PB1 PA HA NP NA M N Polymerase complex PA PBL PB2 Genome 8 segments, SS,(-)sense NS1, NS2: non-structural proteins(some NS2 also in virions)
Virion Structure - Diagram Envelope glycoproteins (spikes): Hemagglutinin (HA) Neuraminidase (NA) M1: matrix M2: ion channel NP: nucleoprotein helical nucleocapsid Polymerase complex PA, PB1, PB2 Genome: 8 segments, SS, (-) sense NS1, NS2: non-structural proteins (some NS2 also in virions)
3. Influenza Virus Composition Nomenclature for Designation of Subty pes of Influenza Type of nuclear material Neuraminidase A/Beijing/32/92(H3N2) Virus Geographic Strai Year of Virus subtype type ongIn number solation
3. Influenza Virus Composition Nomenclature for Desi g yp nation of Subtypes of Influenza Type of nuclear material Hemagglutinin Neuraminidase A/Bei jin g/32/92 (H3N2 ) Hemagglutinin Virus type Geographic origin Strain number Year of Isolation Virus subtype jg ( ) type origin number Isolation
3.1 Hemagglutinin(HA) 1. Integral membrane protein 2. Responsible for binding of virions to host cell via sialic acid receptors 3. Responsible for fusion of virus envelope with endosomal membrane 4. Major antigen to which neutralizing(protective)antibodies develop within the infected host 5. HAO cleaved into HA1 HA2 by cellular protease, required for fusion function 6. Ha binds to sialic acid on the surface of RBc(Red blood cell) to cause the‘ hemagglutination” of rbc's
3.1 Hemagglutinin (HA) 1. Integral membrane protein Integral membrane protein 2. Responsible for binding of virions to host cell via sialic acid rece ptors 3. Responsible for fusion of virus envelope with endosomal membrane 4. Major antigen to which neutralizing (protective) antibodies develop within the infected host 5. HA0 cleaved into HA1 + HA2 by cellular protease, required for fusion function 6. HA bi d t i li id th f f RBC (R d bl d ll) HA bi n ds to sialic acid on the sur face o f RBC (R e d bloo d cell) to cause the “hemagglutination” of RBC’s