34 BIO 326R Influenza - BIO 326R Influenza Orthomyxovirus...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
BIO 326R Influenza
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Orthomyxovirus Negative sense RNA, segmented genome 8 segments, ~13kb total Segments are analogous to chromosomes, a virion must have one copy of each segment to be viable No partitioning mechanism – many particles are not viable Influenza is an enveloped virus, but is unusually stable (can be transmitted from hands, doorknobs, etc.) Proteins Neuraminidase (N or NA) and Hemagglutinin (H or HA) on envelope surface Matrix proteins (M 1 and M 2 ) M2 partially exposed on envelope Nucleoprotein (NP) found tightly associated with viral RNA (each segment has its own associated NP) Nomenclature Influenza type A, B and C Type A undergoes antigenic shift All undergo antigenic drift C is somewhat rare and causes mild symptoms Type/site first identified/year identified (H_N_) e.g. A/New York/2003(H3N2) means influenza type A, first found in New York, in 2003, HA type 3, NA type 2 Sixteen different hemagglutinins and nine different neuraminidases identified so far
Background image of page 2
Lifecycle HA on viral envelope binds to sialic acid residues on cell surface, and possibly some specific glycoproteins Some limited cleavage of sialic acid by neuraminidase can occur here, may prevent clumping of cells in vitro , HA glycoprotein alone will cause aggregation of many kinds of cells, the name hemagglutinin is derived from its ability to cause clumping of erythrocytes Virion endocytosed into cytoplasm Acidification of the endosome promotes fusion of envelope with endosomal membrane and release of viral RNA particles into cytoplasm (NP are still attached to RNA) M 2 protein is a proton channel , acidification of capsid interior causes conformational change in HA, initiating the fusion of envelope to endososomal membrane vRNA transported from cytoplasm to nucleus Transcription of mRNA and full length copy (cRNA, serves as replication template) within nucleus Assembly proceeds through Golgi, viral particles released through budding NA activity allows release from cell surface
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Endocytosis and acidification of endosome. Interior of envelope acidified via M2 proton channel H+ Fusion and uncoating RNPs transported to nucleus Transcription of mRNA and cRNA, Translation of viral mRNA Binding of HA to sialic acid packaging budding HA, NA, M2 Translated in ER, processed in Golgi cRNA M1, capsid mRNA
Background image of page 4
Pathogenesis Host range Type A can infect humans, birds, pigs, and even whales, horses, seals, felines…. Type B and C restricted mostly to humans Primary infection in upper respiratory tract Cytotoxic effects on ciliated and mucus producing cells Release from apical (lumen) surface Transport to lungs Infectious aerosols are released from coughing, sneezing, talking etc. Infection in lungs causes desquamation in lungs - may
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 15

34 BIO 326R Influenza - BIO 326R Influenza Orthomyxovirus...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online