PHGY 313 Lecture Notes - Lecture 21: Respiratory Tract, Viral Envelope, Mda5
24 May 2016
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Document Summary
Infects upper respiratory tract of humans, horses, birds, pigs, seals. Spherical particles enclosed in lipid bilayer without protruding hemagglutin and neuraminidase spikes. Inside viral envelope, there are 8 ssrna associated with nucleoproteins; these encode 10 proteins. Hemagglutin = allow attachment of virus to host. Neuraminidase = cleaves sialic acid from viral and host cell glycoproteins; allows escape. Feature of influenza virus is antigenic variation: virus can change the 2 surface proteins much more than the internal proteins. Persistence in the species and then jumping to another species. Viral proteins variation allows for flue persistence and change. 2 different mechanisms make antigenic variation in ha and na. Antigenic drift = series of spontaneous point mutations gradually minor changes in ha and. Antigenic shift = sudden emergence of a new subtype of influenza with very different ha and. Endosomes contain tlr3 (ssrna) and tlr7 (dsrna), which recognize viral rna. Cytosol contains rig-i and mda-5, which recognize dsrna if they escape from endosomes.
