Lecture 2- overview of the virus
1. The ﬁrst step- the virus binds to a receptor-->entry and uncoating--> early gene expression-->replication of viral genome-->late gene expression->assembly of viral progeny-->exit 2. Concept 2.1- Virus entry is a multistep process with the
ultimate goal of delivering viral genome (payload) into the
A. Binding to surface receptors-
- a viral receptor is cell surface molecule, likely a transmembrane protein - a virus may need multiple receptors to enter the cell
-the ability of viruses to infect certain cells but not others are typically due to the fact that only the "permissive cells" display the right viral receptors. This is called virus "tropism"
-many viruses are species-speciﬁc, partially due to receptor differences.
B. membrane structure and hydrophobicity
- transmembrane protein: a protein that span across the membrane lipid bilayer, at least once.
-lipid bilayer- made of lipids. Arranged head to tail because they are hydrophobic.
i. What is hydrophobic?
- hydro- water
-phobic- a very strong feeling opposite of love- the molecules hate water. -hydrophilic- water loving head.
3. Concept 2.2- the viral receptors is displayed on the cell surface.
A. Identiﬁcation of HIV receptors: part 1
i. a cell surface molecule called CD4 is the primary receptor of HIV. - HIV only infects a subset of human T cells.
- a lot of contributors in identiﬁcation of receptor.s.
-permissive cells-can be infected
-non permissive cells- cannot be infected.
-macroviroc: also called selzentry is an inhibitor of CCR5, a coreceptor for HIV entry.
Viral tropism refers to:
The fact that the virus an affect certain cell types but not others.
B. receptor binding and disease implications: the case of H5N1 -H5N1: avian ﬂu virus: named after the two surface glycoproteins HA ( hemagglutinin) and NA ( neuraminidase)
i. Normally affects but not cause disease in aquatic birds. (...
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