Textbook Chapter 4 Virus Entry

Question 1

Viral capsid or envelope proteins bind to specific receptors on the cell surface which could be what?

Answer 1

they could be sugar residues on glycolipids, glycoproteins, or a variety of cellular membrane proteins

Question 2

in some cases, virions subsequently bind to a second receptor. What does this do for the virion?

Answer 2

mediates entry into the cell

Question 3

how do enveloped virus particles deliver their nucleocapsids into cells?

Answer 3

by fusion of the viral envelope with a cellular membrane

Question 4

in some cases, fusion occurs where?

Answer 4

directly at the cell surface with the plasma membrane

Question 5

in other cases how does fusion occur?

Answer 5

enveloped virions are taken up in endosomes which mediate fusion by low pH, caveosomes, or pinocytic vesicles before fusion occurs

Question 6

what is a well studied fusion of endosomes mediate low pH?

Answer 6

fusion carried out by the HA protein of influenza virus

Question 7

What are the two ways viruses that do not have envelopes penetrate membranes?

Answer 7

1. through lysis of the endosomal membrane

2. by insertion of viral proteins into the membrane, allowing passage of the viral genome directly into the cytosol

Question 8

the nucleocapsids of many DNA viruses are transported to the nucleus how?

Answer 8

by dyneins on microtubules and either pass directly through the nuclear pores or are disassembled at the nuclear pore